Is there a glossary about which infrared (IR) colors which body parts reflect?

Is there a glossary about which infrared (IR) colors which body parts reflect?

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I am doing medical research and I'm trying to find parts of the body that look about the same to the human eye, but reflect different "colors" in IR, so that using a light source and a camera of that frequency helps to distinguish between them. Thus I was wondering if there is a glossary out there that lists all the colors (visible or invisible to the human eye) for all body parts (cells, bacteria, organs etc.) that get reflected.

I'd also be interested in literature on that topic, but it's sort of difficult to feed the right words into search engines without getting tons of unrelated results.

Infrared Light

There are two types of IR security cameras available, each with very different technologies. Laser IR illuminators and thermal imaging are both part of the IR spectrum, which is measured by the amount of energy in a light wave related to its wavelength. Shorter wavelengths have higher energy, and conversely, longer wavelengths have lower energy. IR light is emitted by an object at the atomic level, making it invisible to the naked eye.

IR light can be split into three categories:

Near-infrared (near-IR) – Closest to visible light with wavelengths ranging from 0.7 to 1.3 μm, or 700 to 1300 billionths of a meter.

Mid-infrared (mid-IR) – Has wavelengths ranging from 1.3 to 3 μm. Both near- and mid-IR are used by a variety of electronic devices, including remote controls.

Thermal-IR – Occupying the largest part of the IR spectrum, thermal-IR has wavelengths ranging from 3 to over 30 μm.

The key difference between IR illumination and thermal-IR is that thermal-IR “sees” the energy emitted by an object instead of reflecting IR light off an object using laser or LED IR illuminators.

Figure 3-13 presents a comparison of three types of cameras focused on a rural environment. These security cameras would react differently within a highly illuminated urban environment, using the reflection of multiple street and building lightings to make the scene more visible. But what would happen in a blackout? When this occurs, the ability to directly “see” the energy, rather than rely on reflected light, becomes essential. The first camera in Figure 3-13 is a fixed 2-megapixel, higher quality camera, with one image shot during the day and the other in the middle of a moonless night. The daytime photo is of exceptional quality with lots of detail in the flora and even in the sky. The night shot lacks all detail but a subtle light in the sky toward the horizon and the bright street lighting.

Figure 3-13 . The urban environment makes it easy to see in the dark. This is a high-performance professional PTZ security camera during the day and then night, zooming into the entrance of the far building.

Next, the indoor/outdoor fixed 48 LED IR analog NTSC camera shows a daytime shot depicting a cloud covering and a nighttime shot with the LED IR lights only able to reach the bushes 12 feet. away, and everything else beyond the LED IR 30-foot limitation. The fixed FLIR thermal analog NTSC camera doesn't require any IR illumination because it reads the existing IR spectrum at the atomic level. Not only are you able to see the suspicious figure about 50 feet away but also the sky, horizon, trees, bushes, and lights.

IR illuminators are very popular with security cameras from the economical models up to laser IR illuminators added to long-range cameras. The economical brands typically add a few dozen LED IR lights around the fixed camera lens to reflect IR off the monitored objects. The addition of these IR LED lights provides the fixed camera with the ability to literally see in the dark. There are dozens of brands that offer this feature in a variety of styles from bullet enclosures to vandal-resistant domes, all for less than $200. These cameras typically use the same CMOS or CCD sensors as other security cameras, even the same (plastic and/or glass) lenses, but the one problem I've come across with these cameras is the same problem with most outdoor cameras – dirt. In this case, the dirt doesn't necessarily block the view, but it does confuse the light sensor, which is what determines when to turn on the LED IR lights. It also reflects the IR light onto itself, creating a washed-out, low-contrast image during the day.

Professional solutions to this problem include a separate IR illuminator installed next to a higher quality camera, or a laser IR illuminator that focuses the IR light on a pinpoint far away. Depending on the manufacturer, power, and sophistication, these solutions can cost thousands of dollars. Supplementing a PTZ camera with illuminators can be costly, as only one illuminator can light up the entire area-of-coverage capabilities of a PTZ camera with 35× zoom.

Color & Heat Absorption

This is a compilation of information from students who are conducting scientific color experiments about color and heat absorption.

#1 - I am doing a science fair experiment on color vs. heat absorption. I need ideas on research.
#2 - When using a thermometer, is it better to use cloth or construction paper?
#3 - Is it better to use a light source or the sun? Ben Franklin's research with cloth and snow sounds interesting. Has anyone tried to set that one up?

Best Scientific Answers
Color and Heat Absorption - from "Ask a scientist"
Color and Heat Absorption - from MadScientst Network
Best Student Experiment

Heat Absorption and Emissivity - Information from others

JP : As you probably already know, dark colors (black) will heat up more than light colors (white). Try using thermometer strips sold at pet stores (to stick on the insides of reptile cages to monitor temperature). They're cheap, don't break, are flat so you can put them under a piece of paper (if that's what material you're using) to check your temperatures. Try some materials with different reflective surfaces too (foil shiny black vs. rough-surfaced black for example).

Chris Willard : I would follow Ben Franklin's observations, put different colors on a block of ice (he used snow). Set the ice in the sun and observe how the darker colors melt down into the ice faster (presuming it will, I've not tried this). another idea might be to set a thermometer under pieces of cloth that are set in the sun or under a lamp to measure different temperatures.

Anonymous: White reflects more energy than black does. Absorbed energy is of course not destroyed but usually converted to heat so the answer to your question is yes, makes a difference.

Mac : Color can affect heat absorption because of emissivity. A number of variables can enter into the picture, so if you conducted an experiment, you'd need to proceed carefully, to avoid skewed results. Emissivity would probably be the key differentiator in your question. (Look up emissivity in the dictionary).

Given two identical glass containers - one being of one color A and another being of another color B and that they would be filled with, say, some identical heated liquid, and then allowed to cool -

And given that the emissivity of container colored A and the emissivity of container colored B is substantially different, then the rates of cooling would be different. [You would need to measure or otherwise determine what the 'emissivity' of each specifically colored glass is.]

Emissivity of materials is of significant concern in some industries - for instance - if you are building a spaceship - and you want to keep parts of the spaceship cool or other parts warmer. The 'color' (more precisely, the emissivity) of the surface of the ship will determine whether that portion of the spaceship will be cold, cool, warm, or hot.

There are lists that give the values of emissivity of various materials - in books on spacecraft design, thermal properties handbooks, and similar texts.

Two of the main attributes you would want to look at in an experiment that would demonstrate this would be 1. the material's emissivity and 2. the material's thermal conductivity.

To remove multiple external variables from your experiment - you might want to place both of the glasses of liquid into a black box (keeping them out of sunlight/away from external heat / light sources). Don't put them in the microwave either! :-)

And if do perform an experiment - if you use two thermometers or thermocouples, be sure they are calibrated. And gosh - publish your findings here if you do perform the experiment.

If you paint one glass Black and the other glass White, which container do you think will cool faster? Any hunch?

Anonymous: About the absorption of heat and emissivity in coffee cups: The cups would take heat energy from the coffee at same rate, given same material of cup, as this is conductive heat transfer, while the white cup will radiate heat to surrounding air more slowly than the black cup, and so in total the black cup of coffee will cool down quicker.

An excellent student experiment about color and heat absorption

The following is documentation of a student's experiment with color and heat absorption. We only know her as "Madeline" and here's the research that she posted on the bulletin board at Color Matters, January, 2000.

Does the amount of thermal energy (heat) produced by a colored fabric after 30 minutes of intense light relate to its position in the spectrum?

When a color (colored fabric) absorbs light, it turns the light into thermal energy (heat). The more light a color absorbs, the more thermal energy it produces. Black fabric absorbs all colors of light and is therefore warmer than white fabric which reflects all colors. I predict that the colors of the spectrum appearing the darkest and most like black (violet, indigo, and forest green) will produce the most thermal energy. The other colors (red, orange, and yellow), will produce the least thermal energy because they appear lighter or more like white.

1. a thermometer (preferably an indoor/outdoor thermometer because they have the largest temperature range)
2. a 1&rsquo x 1&rsquo piece of heavy corrugated cardboard
3. tape
4. a clock, stopwatch, or timer
5. sunlight (If you&rsquore short on sunlight, use a with a halogen floodlight, at least 100 watts. A halogen bulb is a good choice because it has a high light intensity and its light spectrum is very similar to sunlight.)
6. six 100% cotton T-shirts (or pieces of cloth) in red, orange, yellow, forest green, indigo, and violet

A simple way to measure how much thermal energy a colored material produces is to measure the changes in its temperature:
1. Tape the thermometer in the center of the cardboard. Make sure the tape doesn&rsquot cover the thermometer bulb.
2. Set the cardboard/thermometer indoors, out of direct sunlight.
3. Lay the red cloth over the cardboard/thermometer so it is touching the thermometer bulb.
4. Set the lamp so the bulb is 2 feet away from and perpendicular to the cardboard/cloth.
Turn the lamp on.
5. Position the cardboard/cloth so the thermometer bulb is in the center of the beam of light.
6. Wait 30 minutes, then record the temperature under the cloth.
7. Turn the light off and take the cloth off the cardboard.
8. Repeat steps 3 through 8 using each of the other colors of cloths. (Orange, yellow, forest green, indigo, violet.)
9. Repeat the experiment at least 6 times and calculate the average temperatures for each color.

My hypothesis is correct. The darker colors (forest green, indigo, violet) produced the most thermal energy after 30 minutes of intense light. The lighter colors (red, orange, yellow) produced smaller amounts of thermal energy. (The average recorded temperature (°F) for each of the colors is shown in Graph 1.) Interestingly, the temperatures of the fabrics fell in to two groups instead of increasing as the colors got closer to violet. The difference between the temperatures of the red, orange, and yellow fabric was minimal, only 10ths of a degree. The same thing was true for violet, indigo, and forest green fabric. However, the difference between the temperatures of the two groups was a little more than 3 degrees (Fahrenheit). In conclusion, even though violet, indigo, and forest green are generally referred to as "cool" colors, you will be warmer if you wear them! You may not be any warmer if you wear blue instead of green, or green instead of purple. Similarly, it won&rsquot make a difference if you wear red instead of yellow, or yellow instead of orange, but on a hot day, wear one of the warm colors!

Gardner, Robert. Science Projects About Light. Springfield, New Jersey: Enslow Publishers, Inc., 1994, p. 92
Morton, J.L. Color Matters - ElecroMagnetic Color - 1995-1999

About Light
There are many different kinds of light. The different kinds have different wavelengths. Ultraviolet light, for example, has a wavelength of 10-8 meters. Visible colors have a wavelength of about 10-6 meters, the diameter of a bacteria. Infrared light also has a wavelength of about 10-6 meters, but has a longer wavelength than the visible colors. The different colors of visible light have different wavelengths, but the wavelengths are very similar. Violet light has the shortest wavelength, is the coolest, and is closest to ultraviolet light. Red light has the longest wavelength, is the warmest, and is closest to infrared light. The other colors of visible light increase in wavelength and warmth as they get closer to red and infrared light. (For example, yellow light has a longer wavelength and is warmer than indigo light.)

When you shine white light (the light that includes all the visible colors) on a colored object, the object will appear to be the color of the light it reflects. All the other visible colors are absorbed. If the object reflects a warm color (red, orange, yellow) it will be cooler than an object which absorbs them. For example, if you shine light on a blue object, it will absorb the warm red light, and will be warmer than a red object which would reflect that light.

Results of Experiment (completed 8 times)

Cloth Color Red Orange Yellow Dk. Green Indigo Violet
Temperature( F) 76 77 76 80 81 78
78 76 77 76 82 78
76 77 78 83 79 82
76 79 77 80 81 84
78 78 76 86 83 82
78 75 78 81 82 80
78 78 79 79 78 84

77 77 77 81 81 80 Standard Deviation 0.991031 1.246423 1.035098 2.915476 1.642081 2.390457
Average Temp. ( F) 77.13 77.13 77.25 80.75 80.88 81

Does a pink jail cell calm an angry prisoner? Will a pink locker room make a football team weak? Find out at Color Matters: Drunk Tank Pink

Links to More Science Projects

Here's a compilation of all the pages with information from students who are conducting scientific color experiments.

You might also be interested in .

Does a pink jail cell calm an angry prisoner? Will a pink locker room make a football team weak? Find out at Color Matters: Drunk Tank Pink

Landsat Glossary

Acquisition - (1) An image captured by a satellite sensor. (2) The process of searching for and locking onto a received signal.

Acquisition Date - The date the image was acquired. Format: YYYY/MM/DD

Acquisition of Signal - The time a site receives a signal from a spacecraft.

Algorithm - In the context of remote sensing, algorithms generally specify how to determine higher-level data products from lower-level source data. For example, algorithms prescribe how atmospheric temperature and moisture profiles are determined from a set of radiation observations originally sensed by satellite sounding instruments.

Altitude - The angle, in degrees, above the level horizon where an object in the sky appears (the height in space).

Analog - A form of transmitting information characterized by continuously variable quantities, as opposed to digital transmission, which is characterized by discrete bits of information in numerical steps. An analog signal is used to transmit audio (such as voice, radio, stereo, and control tones) and is responsive to changes in light, sound, heat and pressure.

Analog-to-Digital Conversion - The process of converting analog signals to a digital representation.

Anomaly - (1) A deviation from the norm. (2) The angular distance between the position of a planet and its last perihelion (point nearest to the sun), or between that of a satellite and its last perigee (point nearest to the center of the earth).

Antenna - A device for transmitting and receiving radio waves.

Aperture - The diameter of an opening the diameter of the primary lens or mirror of a telescope. A cross-sectional area of the antenna that is exposed to the satellite signal.

Ascending Node (AN) - Direction a satellite is traveling relative to the Equator. An ascending node implies a northbound Equatorial crossing.

Asychronous - Not synchronized.

Attitude - The angular orientation of a remote sensing system with respect to a geographical reference system. The orientation of the sensor along with information about the accuracy and precision with which this orientation is known. This data is required to perform proper calibration of instrument data. The attitude is usually stored in Euler angle or quaternion form and may be 1) calculated by the on-board computer and telemetered to the ground or 2) calculated by ground processing facilities using a variety of attitude sensor data.

Band (channel) - A slice of wavelengths from the electromagnetic spectrum. Landsat ETM+ has eight bands that collect radiation from different parts of the electromagnetic spectrum. Of the eight bands, three bands are visible light, one band is panchromatic, three bands are infrared, and one band is thermal infrared.

Band Gain - The band gain condition detected at the start of a WRS scene. H indicates band acquired in high gain mode. L indicates band acquired in low gain mode.

Bit - A single digital unit of information.

Bit Error Rate - The fraction of a sequence of message bits that are in error (a bit error rate of 10-6 means that there is an average of one error per million bits).

Browse data - A reduced data volume representation of an image scene that can be viewed to determine general ground area coverage and cloud coverage. Browse data typically consist of three spectral bands.

Calibration - The act or process of comparing certain specific measurements in an instrument with a standard.

Calibration Data - In remote sensing, measurements pertaining to the spectral or geometric characteristics of a sensor or radiation source. Calibration data are obtained by using a fixed energy source such as a calibration lamp, a temperature plate, or a geometric test pattern.

Calibration Parameter File (CPF) - The Calibration Parameter File (CPF) supplies the radiometric and geometric correction parameters required during Level 1 processing to create superior products of uniform consistency across the Landsat 7 system. They fall into one of three major categories: geometric parameters, radiometric parameters, or artifact removal parameters. Each CPF is stamped with applicability dates then sent to the LP DAAC for storage and eventual bundling with outbound Level 0 products. The Image Assessment System (IAS) updates and distributes the CPF at least every 90 days.

Channel - A one-way communications link. (also see Band)

Coherent Noise - A spurious, periodic pattern of noise within an image, generally of electronic origin.

Data Continuity - A NASA requirement to ensure that Landsat 7 data are compatible to those obtained by earlier Landsat satellites.

Data set - A logically meaningful grouping or collection of similar or related data.

Descending node - Direction a satellite is traveling relative to the Equator. A descending node implies a southbound Equatorial crossing.

Digital - A means for encoding information in a communications signal by using bits (binary digits). Conversion of information into bits of data for transmission through wire, fiber optic cable, satellite, or over air techniques. Method allows simultaneous transmission of voice, data or video.

Downlink - A communications channel for receiving transmissions from a spacecraft.

Dynamic Range - The range between the maximum and minimum amount of input radiant energy that an instrument can measure.

Electromagnetic - Relating to the interplay between electric and magnetic fields.

Electromagnetic radiation - Energy transfer in the form of electromagnetic waves or particles that propagate through space at the speed of light.

Electromagnetic spectrum - The entire range of radiant energies or wave frequencies from the longest to the shortest wavelengths--the categorization of solar radiation. Satellite sensors collect this energy, but what the detectors capture is only a small portion of the entire electromagnetic spectrum. The spectrum is usually divided into seven sections: radio, microwave, infrared, visible, ultraviolet, x-ray, and gamma-ray radiation.

Enhanced Thematic Mapper Plus (ETM+) - The sensor aboard Landsat 7 that picks up solar radiation reflected by or emitted from the Earth.

Ephemeris - A table of satellite orbital locations for specific time intervals. The ephemeris data help to characterize the conditions under which remotely sensed data are collected and are commonly used to correct the sensor data before analysis.

Equator - An imaginary circle around a body that is everywhere equidistant from the poles, defining the boundary between the northern and southern hemispheres.

EROS Center - Earth Resources Observation and Science Center is a national archive, production, distribution, and research facility for remotely sensed data and other geographic information.

ETM+ Format 1 - The ETM+ Format 1 major frames contain all data (e.g., imaging and calibration) from and associated with Bands 1-6. The MSCD and PCD data are duplicated in both ETM+ formats.

ETM+ Format 2 - The ETM+ Format 2 major frames contain all data (e.g., imaging and calibration) from and associated with Bands 6-8. The MSCD and PCD data are duplicated in both ETM+ formats.

Full WRS Scene - A full WRS scene with overlap is 375 ETM+ scans. A nominal scene without overlap is 335 ETM+ scans. Due to a movement of the bumpers, which resulted in a larger turn-around interval and an increase in the nominal number of minor frames per major frame (from 7,423 to 7,473), the nominal size of a scene without overlap may decrease. Further bumper wear changes may decrease the number of scans without overlap. The number of overlap scans will increase to compensate for the decrease in the non-overlap scene size.

Gain - (1) A general term used to denote an increase in signal power in transmission from one point to another usually expressed in decibels. (2) An increase or amplification. (3) A measure of amplification expressed in dB.

Gaussian Noise - Statistically random radio noise characterized by a wide frequency spectrum that is continuous and uniform over a specified frequency band.

Geostationary orbit - "Describes an orbit in which a satellite is always in the same position (appears stationary) with respect to the rotating Earth. The satellite travels around the Earth in the same direction, at an altitude of approximately 35,790 km (22,240 statute miles) because that produces an orbital period equal to the period of rotation of the Earth (actually 23 hours, 56 minutes, 04.09 seconds). A worldwide network of operational geostationary meteorological satellites provides visible and infrared images of Earth's surface and atmosphere."

Gimbal - A device with two mutually perpendicular and intersecting axes of rotation, thus giving free angular movement in two directions, on which an object may be mounted.

Greenwich Mean Time (GMT) - The mean solar time of the meridian of Greenwich, England, used as the prime basis of standard time throughout the world.

High Gain/Low Gain Antenna - A high gain antenna is highly focused, whereas a low gain antenna receives or transmits over a wide angle.

Infrared radiation - Electromagnetic radiation with wavelengths between about 0.7 to 1000 micrometers. Infrared waves are not visible to the human eye. Longer infrared waves are thermal infrared waves.

Interval - The time duration between the start and end of an imaging operation (land observation) by the ETM+ instrument on board the Landsat 7 spacecraft. The raw wideband data collected during an interval consists of a contiguous set of WRS scenes.

Landsat - Landsat is a partnership between the National Aeronautics and Space Administration (NASA) and the U.S. Geological Survey (USGS). Since 1972, Landsat data have provided a unique resource for those who work in agriculture, geology, forestry, regional planning, education, mapping, and global-change research.

Data from the satellites have been used for monitoring land cover conditions, geological / mineralogical exploration, urban growth, and cartography. Global coverage is available and data sets are provided by the USGS at the cost of reproduction.

Landsat 7 Contact Period - The time duration between the start and end of raw wideband data transmissions from the Landsat 7 spacecraft to a ground station [e.g., the Landsat 7 Ground Station (LGS).

Latitude - The angular distance North or South from the Earth's equator measured in degrees with the equator at 0o and the poles 90o N and 90o S.

Level 0R Files - The generic term used to denote the grouping of band, MSCD, PCD, and calibration data files for a single subinterval.

Level 0R product - A US data product in which the data has been spatially reformatted but the data values remain unchanged. No radiometric or geometric corrections have been performed on the data. The reformatting is fully reversible. The data is band sequential. Attached to the image data are radiometric calibration image data, payload correction data, quality data, and metadata.

Level 0R Quality and Accounting Data - The data quality and accounting information collected by the Landsat 7 Processing System (LPS), on a subinterval basis, from processing of the ETM+ major frames constructed from the wideband Virtual Channel Data Units (VCDUs) received during a Landsat 7 contact period.

Longitude - The angular distance East or West between the meridian of a particular place on Earth and that of Greenwich, England, expressed in degrees or time.

Loss of Signal - The inability to receive a satellite signal because the satellite's orbital path has taken it below the antenna's horizon.

Lower Scene Corners - The corners associated with the leading edge (last scan) of a scene. For descending path scenes, the lower left corner corresponds to the southwest corner of a scene and the lower right corner corresponds to the southeast corner of a scene. For ascending path scenes, the lower left corner corresponds to the northeast corner of a scene and the lower right corner corresponds to the northwest corner of a scene. These mappings hold for the band file geolocation fields and the metadata file.

LPS (output) Files - The generic term used to denote the grouping of Level 0R, browse, and metadata files for a single subinterval. L0R files contain image data, cal data, PCD, and MSCD. Multi-band browse scenes file and metadata file contained in the LPS Output File Set.

Mercator - Of, relating to, or drawn on the Mercator projection (a conformal map projection with the meridians drawn parallel to each other and the parallels of latitude drawn as straight lines whose distance from each other increases with their distance from the equator).

Metadata - A set of descriptive information about the scene data contained in the archive. The information is sufficient for a user, during the process of scene query and selection, to determine at a minimum geographic coverage, date of collection sensor gain mode, time of acquisition, cloud cover, and other quality measurements.

Missions Operations Center (MOC) - The place where the satellite or spacecraft receives coded instructions and delivers data. The coordination place (usually on Earth) for any space mission.

Modulation - The variation of a property of an electromagnetic wave or signal, such as its amplitude, frequency, or phase.

Mosaicking: - The assembling of photographs or other images whose edges are cut and matched to form a continuous photographic representation of a portion of the Earth's surface.

Multispectral - Sensing in usually 4 distinct wavelength bands (equivalent to colors, not all of which are visible to the human eye). Because the data handling capacity of the sensor is spread over these different wavelengths, this usually translates to lower resolution than panchromatic.

Multispectral image - A remote sensing image created using data collected from more than one band.

Multispectral Scanner (MSS) - A line-scanning instrument flown on Landsat satellites that continually scans the Earth in a 185 km (100 nautical miles) swath. On Landsats 1, 2, 4, and 5, the MSS had four spectral bands in the visible and near infrared with an IFOV of 80 meters. Landsat 3 had a fifth band in the thermal infrared with an IFOV of 240 meters. The MSS is a non-photographic imaging system that utilizes an oscillating mirror and fiber optic sensor array. The mirror sweeps from side to side, transmitting incoming energy to a detector array that sequentially outputs brightness values (signal strengths) for successive pixels, one swath at a time. The forward motion of the sensor platform carries the instrument to a position along its path where it can image an adjacent swath.

Nadir - Point on Earth directly beneath a satellite, the opposite of zenith.

NASA - National Aeronautics and Space Administration (NASA) was established in 1958 through the National Aeronautics and Space Act as an outgrowth of the National Advisory Committee for Aeronautics.

Noise - Any unwanted and unmodulated energy that is always present to some extent within any signal.

Orbit - The path of a body acted upon by the force of gravity.

Orbital period - The time it takes a satellite to complete one revolution (orbit) around the Earth. The orbital period of Landsat 7 is about 1.5 hours.

Oscillator - A device for producing alternating current.

Panchromatic - Sensitive to all or most of the visible spectrum, between 0.4 and 0.7 micrometers. Landsat 7 has a panchromatic band.

Partial Scene - A partial scene (less than 375 scans) may exist at the beginning or end of a subinterval because imaging events do not always start or end on WRS scene boundaries. If generated, browse and scene metadata for these occurrences accurately reflect their partial scene nature and geographic extent.

Passive Sensor - A type of remote sensing instrument, a passive sensor picks up radiation reflected or emitted by the Earth. ETM+ is a passive remote sensing system.

Payload Correction Data (PCD) - Imaging support data imbedded in the wideband data stream. Includes satellite attitude, ephemeris, time, angular displacement sensor (ADS) data, and payload state.

Pixel - An abbreviation of picture element. The minimum size area on the ground detectable by a remote sensing device. The size varies depending on the type of sensor.

Polar orbit - An orbit with an orbital inclination of near 90 degrees where the satellite ground track will cross both polar regions once during each orbit. The term describes the near-polar orbits of spacecraft.

Pseudorandom - Being or involving entities (as numbers) selected by a definite computational process that satisfy one or more standard tests for statistical randomness.

Quantization - 1) To subdivide into small but measurable increments. 2) To calculate or express in terms of quantum mechanics

Radar - "Short for ""radio detection and ranging,"" radar sends out short pulses of microwave energy and records the returned signal's strength and time of arrival."

Radiometer - A device that detects and measures electromagnetic radiation.

Radiometric - Relating to, using, or measured by a radiometer. The measurement of radiation.

Raster Data - An abstraction of the real world where spatial data is expressed as a matrix of cells or pixels, with spatial position implicit in the ordering of the pixels. With the raster data model, spatial data is not continuous but divided into discrete units. This makes raster data particularly suitable for certain types of spatial operations (e.g., overlays or area calculations). Unlike vector data, there are no implicit topological relationships.

Raster Graphics - Graphics in which an image is generated by scanning an entire screen or page and marking every point as black, white, or another color (as opposed to vector graphics).

Rasterize - The process of converting vector points, lines, and areas into raster image format.

Raw Data - Numerical values representing the direct observations output by a measuring instrument transmitted as a bit stream in the order they were obtained.

Real-time - Time in which reporting on events or recording of events is simultaneous with the events. For example, the real time of a satellite is the time in which it simultaneously reports its environment as it encounters it.

Remote Sensing - (1) In the broadest sense, the measurement or acquisition of information about some property of an object or phenomenon, by a recording device that is not in physical or intimate contact with the object or phenomenon under study. (2) Instruments that record characteristics of objects at a distance, sometimes forming an image by gathering, focusing, and recording reflected light from the Sun, or reflected radio waves emitted by the spacecraft.

Resampling - Modifying the geometry of an image (which may be from either a remotely sensed or map data source). This process usually involves rectification and/or registration.

Resolution - (1) A measure of the amount of detail that can be seen in an image the size of the smallest object recognizable using the detector. (2) Intensity or rate of data sampling. In remotely sensed imagery, resolution is significant in four measurement dimensions: spectral, spatial, radiometric and temporal.

Retrograde - (1) Of or relating to the orbital revolution or axial rotation of a planetary or other celestial body that moves clockwise from east to west, in the direction opposite to most celestial bodies. (2) Of or relating to the brief, regularly occurring, apparently backward movement of a planetary body in its orbit as viewed against the fixed stars, caused by the differing orbital velocities of Earth and the body observed.

Revolution - Orbital motion about a point located outside the orbiting body.

Rotation - Motion around an axis passing through the rotating body.

Row - (1) The latitudinal (nominal) center line of a Landsat scene. (2) The scan lines that constitute an image.

Satellite - Any body, natural or artificial, in orbit around a planet. The term is used most often to describe moons and spacecraft. A man-made satellite is a spacecraft that orbits another body, such as a planet or the Sun. A natural satellite is another term for a moon.

Saturation - The intensity of a color. A highly saturated color is a vivid, brilliant color to dull a color (decrease its saturation), you add small amounts of its complement, making it closer to gray.

S-Band - A range of microwave radio frequencies in the neighborhood of 2 to 4 GHz, used for communicating with piloted space missions (

Scan - An image data line produced from a single detector of a band during a scan.

Scan Line - A series of spacecraft pointings in one dimension.

Scanning Mirror - Landsat TM?s scanning mirror collects data on both the forward and reverse scans.

Scenes - Each Landsat image collected is a scene. Each Landsat scene is 115 x 106 miles long. The globe is divided into 57,784 scenes, and each Landsat scene has about 3 billion bytes of data.

Single Event Upsets - A Single Event Upset (SEU) occurs when an energetic particle travels through a transistor substrate and causes electrical signals within the transistor. This is a known phenomenon that usually occurs in near-earth orbit to spacecraft passing through the Van Allen belts, especially the northern and southern auroral zones and the south Atlantic anomaly.

Site - The physical location of an International Ground Station (IGS) or the Mission Operations Center (MOC).

Spatial Data - Any information about the location, shape of, and relationships among geographic features. This includes remotely sensed data as well as map data.

Spatial Resolution - The area on the ground that an imaging system (such as a satellite sensor) can distinguish.

Spectral Range - The wavelength difference between two wavelengths in adjacent orders at the same angle of diffraction

Spectral Response - The relative amplitude of the response of a detector vs. the frequency of incident electromagnetic radiation.

Spectrometer - An optical instrument that splits the light received from an object into its component wavelengths by means of a diffraction grating, then measuring the amplitudes of the individual wavelengths.

Subinterval - A segment of a raw wideband data interval received during a Landsat 7 contact period. Subintervals are caused by breaks in the wideband data stream due to communication dropouts and/or the inability of the spacecraft to transmit a complete observation (interval) within a single Landsat 7 contact period. The largest possible subinterval can be as long as a full imaging interval (a set of contiguous WRS scenes) transmitted during an uninterrupted contact period. The smallest possible subinterval can be as small as a set of a few contiguous ETM+ scans (a partial WRS scene). The smallest size of a subinterval is an operator modifiable parameter in LPS. If the smallest subinterval size is chosen to be as long as a full WRS scene, it will contain approximately 24 seconds worth of ETM+ data or 335 scans (without the 20 overlapping scans each

Sun-synchronous orbit - An orbit in which a satellite is always in the same position with respect to the rotating Earth at the same time of day. The satellite travels around the Earth in the same direction, at an altitude of approximately 438 miles (705 kilometers). Landsat-7 is sun-synchronous, always passing overhead at approximately 10:00 am local time.

Synchronous - The instantaneous alignment of two or more events in time. Events may occur at irregular intervals

Telemetry - (1) Radio signals from a spacecraft used to encode and transmit data to a ground station. (2) The science of measuring a quantity, transmitting the measured value to a distant station, and there, interpreting or recording the quantity measured.

Thematic data - Thematic data layers in a data set are layers of information that deal with a particular theme. These layers are typically related information that logically goes together.

Thermal infrared - Electromagnetic radiation with wavelengths between 3 and 25 micrometers.

Thematic Mapper - "A Landsat multispectral scanner designed to acquire data to categorize the Earth's surface. Particular emphasis was placed on agricultural applications and identification of land use. The scanner continuously scans the surface of the Earth, simultaneously acquiring data in seven spectral channels. Overlaying two or more bands produces a false color image. The ground resolution of the six visible and shortwave bands of the Thematic Mapper is 30 meters, and the resolution of the thermal infrared band is 120 meters. Thematic mappers were flown on Landsat 4 and 5."

U.S. Geological Survey (USGS) - A bureau of the Department of the Interior. USGS was established in 1879 following several Federally sponsored independent natural resource surveys of the West and Midwest. The Department of the Interior has responsibility for most of our nationally owned public lands and natural resources. The USGS monitors resources such as energy, minerals, water, land, agriculture, and irrigation. The resulting scientific information contributes to environmental-policy decision-making and public safety. For example, USGS identifies flood- and landslide-prone areas and maintains maps of the United States.

Universal Transverse Mercator (UTM) Projection - A widely used map projection that employs a series of identical projections around the world in the mid-latitude areas, each spanning six degrees of longitude and oriented to a meridian. This projection is characterized by its conformality that is, it preserves angular relationships and scale and it easily allows a rectangular grid to be superimposed on it. Many worldwide topographic and planimetric maps at scales ranging between 1:24,000 and 1:250,000 use this projection.

Uplink - A connection through which signals transmit to a satellite.

Upper Scene Corners - The corners associated with the trailing edge (first scan) of a scene. For descending path scenes, the upper left corner corresponds to the northwest corner of a scene and the upper right corner corresponds to the northeast corner of a scene. For ascending path scenes, the upper left corner corresponds to the southeast corner of a scene and the upper right corner corresponds to the southwest corner of a scene. These mappings hold for the band file geolocation fields and the metadata file.

Vector Data - Vector data, when used in the context of spatial or map information, refers to a format where all map data is stored as points, lines, and areas rather than as an image or continuous tone picture. These vector data have location and attribute information associated with them.

Visible radiation - The electromagnetic radiation that humans can see as colors. The visible spectrum is composed of wavelengths between 0.4 to 0.7 micrometers. Red is the longest and violet is the shortest. Landsat 7 has three visible bands in red, green, and blue.

Wavelength - The distance from crest to crest, or trough to trough, of an electromagnetic or other wave. Wavelengths are related to frequency: The longer the wavelength, the lower the frequency.

Worldwide Reference System (WRS) - A global indexing scheme designed for the Landsat Program based on nominal scene centers defined by path and row coordinates.

X-band - A nominal frequency range from 12.5 to 8 GHz (2.4 to 3.75 cm wavelength) within the microwave (radar) portion of the electromagnetic spectrum. X-band is a suitable frequency for several high-resolution radar applications and is used for both experimental and operational airborne systems.

Zenith - The point on the celestial sphere directly above the observer. Opposite the nadir.


Although rain is naturally slightly acidic because of carbon dioxide, natural emissions of sulfur and nitrogen oxides, and certain organic acids, human activities can make it much more acidic. Occasional pH readings of well below 2.4 (the acidity of vinegar) have been reported in industrialized areas.

The principal natural phenomena that contribute acid-producing gases to the atmosphere are emissions from volcanoes and from biological processes that occur on the land, in wetlands, and in the oceans. The effects of acidic deposits have been detected in glacial ice thousands of years old in remote parts of the globe. Principal human sources are industrial and power-generating plants and transportation vehicles. The gases may be carried hundreds of miles in the atmosphere before they are converted to acids and deposited.

Since the industrial revolution, emissions of sulfur and nitrogen oxides to the atmosphere have increased. Industrial and energy-generating facilities that burn fossil fuels, primarily coal, are the principal sources of increased sulfur oxides. These sources, plus the transportation sector, are the major originators of increased nitrogen oxides.

The problem of acid rain not only has increased with population and industrial growth, it has become more widespread. The use of tall smokestacks to reduce local pollution has contributed to the spread of acid rain by releasing gases into regional atmospheric circulation. The same remote glaciers that provide evidence of natural variability in acidic deposition show, in their more recently formed layers, the increased deposition caused by human activity during the past half century.

In the context of remote sensing, algorithms generally specify how to determine higher-level data products from lower-level source data. For example, algorithms prescribe how atmospheric temperature and moisture profiles are determined from a set of radiation observations originally sensed by satellite sounding instruments.

The angular distance of an Earth satellite (or planet) from its perigee (or perihelion) as seen from the center of the Earth (sun).

Troposphere stems from the Greek word tropos, which means turning or mixing. The troposphere is the lowest layer of the Earth's atmosphere, extending to a height of 8-15 km, depending on latitude. This region, constantly in motion, is the most dense layer of the atmosphere and the region that essentially contains all of Earth's weather. Molecules of nitrogen and oxygen compose the bulk of the troposphere.

The tropopause marks the limit of the troposphere and the beginning of the stratosphere. The temperature above the tropopause increases slowly with height up to about 50 km.

The stratosphere and stratopause stretch above the troposphere to a height of 50 km. It is a region of intense interactions among radiative, dynamical, and chemical processes, in which horizontal mixing of gaseous components proceeds much more rapidly that vertical mixing. The stratosphere is warmer than the upper troposphere, primarily because of a stratospheric ozone layer that absorbs solar ultraviolet energy.

The mesosphere, 50 to 80 km above the Earth, has diminished ozone concentration and radiative cooling becomes relatively more important. The temperature begins to decline again (as it does in the troposphere) with altitude. Temperatures in the upper mesosphere fall to -70 degrees to -140 degrees Celsius, depending upon latitude and season. Millions of meteors burn up daily in the mesosphere as a result of collisions with some of the billions of gas particles contained in that layer. The collisions create enough heat to burn the falling objects long before they reach the ground.

The stratosphere and mesosphere are referred to as the middle atmosphere. The mesopause, at an altitude of about 80 km, separates the mesosphere from the thermosphere--the outermost layer of the Earth's atmosphere.

The thermosphere, from the Greek thermo for heat, begins about 80 km above the Earth. At these high altitudes, the residual atmospheric gases sort into strata according to molecular mass. Thermospheric temperatures increase with altitude due to absorption of highly energetic solar radiation by the small amount of residual oxygen still present. Temperatures can rise to 2,000 degrees C. Radiation causes the scattered air particles in this layer to become charged electrically, enabling radio waves to bounce off and be received beyond the horizon. At the exosphere, beginning at 500 to 1,000 km above the Earth's surface, the atmosphere blends into space. The few particles of gas here can reach 4,500 degrees F (2,500 degrees C) during the day.

29.92 inches or 760 mm of mercury

1013.25 millibars (mb) or 101,325 pascals (pa).

In radiometry, a relatively narrow region of the electromagnetic spectrum to which a remote sensor responds a multispectral sensor makes measurements in a number of spectral bands.


Near-Infrared Vascular Imaging

Peripheral intravenous (PIV) catheter insertion is a common, painful, and sometimes difficult procedure for many infants and children in the pediatric emergency department (ED) because of the small caliber and impalpability of the veins. Changes in catheter design and adoption of new imaging techniques have been tried to facilitate line placement. Near-infrared (NIR) imaging is a non-invasive and non-ionizing modality that has been employed to improve the success rate of PIV catheter placement in pediatric patients (e.g., reduce the number of attempts, the number of needle redirections, and the overall time to catheter placement). The VeinViewer ® (Luminetx Corporation, Memphis, TN) is a NIR light device that delineates the running course of subcutaneous veins.

In an observational feasibility study, Cuper et al (2011) evaluated for the first time the value of visualizing veins by a prototype of a NIR vascular imaging system for venipuncture in children. Participants were children (0 to 6 years) attending the clinical laboratory of a pediatric university hospital during a 2-month period without (n = 80) and subsequently during a 1-month period with a prototype of an NIR vascular imaging system (n = 45). Failure rate (i.e., more than 1 puncture) and time of needle manipulation were determined. With the NIR vascular imaging system, failure rate decreased from 10/80 to 1/45 (p = 0.05) and time decreased from 2 seconds (1 to 10) to 1 second (1 to 4, p = 0.07). The authors concluded that the findings of this study showed promising results on the value of an NIR vascular imaging system in facilitating venipuncture.

Chapman et al (2011) examined the benefit of the VeinViewer, a device that delineates subcutaneous veins using NIR light and video technology, for PIV placement in children in the ED. A prospective, randomized sample of children aged 0 to 17 years who required a non-emergent PIV in a tertiary care pediatric ED were enrolled in this study. Subjects were randomized to standard PIV cannulation (SC) or PIV cannulation with the VeinViewer (VV). The primary outcome measure was time to PIV placement. Secondary outcome measures included number of PIV attempts and pain scores as reported by the child, parent or guardian, and nurse using a 100-mm visual analog scale (VAS). A total of 323 patients completed the study: 174 boys and 149 girls. Age, sex, and body mass index (BMI) were not different between groups. There were no differences in time to PIV placement, number of PIV attempts, or pain scores for the overall study group. However, a planned subgroup analysis of children age 0 to 2 years (n = 107) did yield significant results for the geometric mean time to place the PIV (121 seconds [VV] versus 167 seconds [SC], p = 0.047) and for nurses' perception of pain (median VAS 34 [VV] versus 46 [SC], p = 0.01). The authors concluded that while no results were significant for the overall study group, subgroup analysis of children age 0 to 2 years suggested that the VeinViewer may decrease the time to PIV placement.

In a randomized controlled trial, Perry et al (2011) examined if the use of a NIR light venipuncture aid (VeinViewer) would improve the rate of successful first-attempt placement of IV catheters in a high-volume pediatric ED. Patients younger than 20 years with standard clinical indications for IV access were randomized to have IV placement by ED nurses (in 3 groups stratified by 5-year blocks of nursing experience) using traditional methods (standard group) or with the aid of the VeinViewer (device group). If a vein could not be cannulated after 3 attempts, patients crossed-over from one study arm to the other, and study nurses attempted placement with the alternative technique. The primary end point was first-attempt success rate for IV catheter placement. After completion of patient enrollment, a questionnaire was completed by study nurses as a qualitative assessment of the device. A total of 123 patients (median age of 3 years) were included in the study: 62 in the standard group and 61 in the device group. There was no significant difference in first-attempt success rate between the standard (79.0 %, 95 % confidence interval [CI]: 66.8 % to 88.3 %) and device (72.1 %, 95 % CI: 59.2 % to 82.9 %) groups. Of the 19 study nurses, 14 completed the questionnaire 70 % expressed neutral or unfavorable assessments of the device in non-dehydrated patients without chronic underlying medical conditions and 90 % found the device a helpful tool for patients in whom IV access was difficult. The authors concluded that first-attempt success rate for IV placement was non-significantly higher without than with the assistance of the VeinViewer in a high-volume pediatric ED. They noted that nurses placing IVs did report several benefits to use of the device with specific patient groups, and future research should be carried out to demonstrate the role of the VeinViewer in these patients.

In a randomized controlled trial, Kim et al (2012) examined if the use of the VeinViewer in infants and children facilitated peripheral venous access, especially in difficult cases. Pediatric patients between the ages of 1 month and 16 years who required peripheral venous access in the pediatric ward were included in this study. Prior to randomization, difficult intravenous access (DIVA) score, a 4-variable clinical prediction rule for first-attempt success, was estimated. These investigators compared the first-attempt success rates and procedural times between the VeinViewer group and a control group. They evaluated 111 patients: 54 in the VeinViewer group and 57 in the control group. Patient demographics and factors related to the success of vein access were similar for both groups. The overall first-attempt success rate was 69.4 % (77/111) in the VeinViewer group and 66.7 % (38/57) in the control group, a difference that was not statistically significant. However, the first-attempt success rate increased from (25 %) 5/20 in the control group to (58 %) 14/24 in the VeinViewer group for difficult veins with a DIVA score greater than 4 (p = 0.026). There were no significant differences in procedural time between the two groups. The authors concluded that the VeinViewer facilitated peripheral venous access for pediatric patients with difficult veins, which enhanced first-attempt success rates.

The AccuVein AV300 device was developed to assist venipuncture and IV cannulation by enhancing the visibility of superficial veins. It uses infrared light to highlight hemoglobin so that blood vessels are darkly delineated against a red background.

Sanchez-Morago et al (2010) stated that despite major advances that have occurred in medicine and biotechnology in recent years, advances to locate veins have been very limited. The AccuVein AV300 is a portable manual instrument that enables nurses to locate certain peripheral veins. This device does not substitute a nurse's traditional skill in locating veins by visual or feeling means, but rather this device supplements their skills and enhances them. This device is lightweight, intuitive, and does not require previous training for its use and hygiene since it never enters into contact with a patient's skin as it emits an infrared light on the skin, which reflects veins drawing them on the surface of the skin.

Kaddoum et al (2012) evaluated the effectiveness of the AccuVein AV300 in improving the first-time success rate of IV cannulation of anesthetized pediatric patients. Participants were randomized to cannulation with the AccuVein AV300 or standard insertion by experienced pediatric anesthesiologists. An observer recorded the number of skin punctures and cannulation attempts required, and the time between tourniquet application and successful cannulation or 4 skin punctures, whichever came first. There were 146 patients with a median age of 4.6 years (range of 0.18 to 17.1 years), 46.6 % were males, 80.8 % were light skin colored, and 15.7 % were younger than 2 years. The first-attempt success rates were 75 % (95 % CI: 63.8 to 84.2 %) using AV300 and 73 % (95 % CI: 61.9 to 81.9 %) using the standard method (p = 0.85). Patients with dark or medium skin color were 0.38 times less likely to have a successful first-attempt than patients with light skin color. The difference between the 2 treatment groups in number of skin punctures and the time to insertion was not significant. Although the AV300 was easy to use and improved visualization of the veins, the authors found no evidence that it was superior to the standard method of IV cannulation in unselected pediatric patients under anesthesia.

de Graaff et al (2014) evaluated the clinical utility of a NIR vascular imaging device (VascuLuminator ® ) in pediatric patients who were referred to the anesthesiologist because of difficult cannulation. There were 226 consecutive children referred to pediatric anesthesiologists by the treating pediatrician of the in- and out-patient clinic, because of difficulties with intravenous cannulation, were included in this cluster randomized clinical trial. The presence and use of the NIR vascular imaging device for peripheral intravenous cannulation (PIC) was randomized in clusters of 1 week. Success at first attempt (Fisher exact test) and time to successful cannulation (Log-rank test) were assessed to evaluate differences between groups. Success at first attempt in the group with the VascuLuminator ® (59 %) was not significantly different from the control group (54 %, p = 0.41), neither was the median time to successful cannulation: 246 s and 300 s, respectively (p = 0.54). The authors concluded that visualization of blood vessels with NIR light and with NIR vascular imaging device did not improve success of PIC in pediatric patients who are known difficult to cannulate.

In summary, there is currently insufficient evidence on the effectiveness of near-infrared vascular imaging for guiding vascular access. Well-designed studies are needed to validate these preliminary findings.

Assessment of Cutaneous Wound

  1. providing basic explanations of imaging technology concepts,
  2. reviewing the wound imaging literature, and
  3. providing insight into areas for further application and exploration.

They stated that non-invasive imaging is a promising advancement in wound assessment and all technologies require further validation.

Near-Infrared Fluorescence Imaging

Schols et al (2013) provided an overview of current developments in surgical optical imaging for improved anatomic identification and physiologic tissue characterization during laparoscopic gastro-intestinal surgery. A systematic literature search in the PubMed database was conducted. Eligible studies reported on any kind of novel optical imaging technique applied for anatomic identification or physiologic tissue characterization in laparoscopic gastro-intestinal surgery. Gynecologic and urologic procedures also were included whenever vascular, nerve, ureter, or lymph node imaging was concerned. Various surgical imaging techniques for enhanced intra-operative visualization of essential tissue types (i.e., blood vessel, bile duct, ureter, nerve, lymph node) and for tissue characterization purposes such as assessment of blood perfusion were identified. An overview of pre-clinical and clinical experiences was given as well as the potential added value for intra-operative anatomic localization and characterization during laparoscopy. The authors concluded that implementation of new optical imaging methods during laparoscopic gastro-intestinal surgery can improve intra-operative anatomy navigation. This may lead to increased patient safety (preventing iatrogenic functional tissue injury) and procedural efficiency (shorter operating time). They stated that near-infrared fluorescence imaging seems to possess the greatest potential for implementation in clinical practice in the near future.

Harke et al (2014) presented a single-surgeon, matched-pair analysis to show the feasibility of combining the technique of selective clamping with usage of NIR fluorescence (NIRF) imaging in robot-assisted partial nephrectomy and to investigate short-term renal function outcomes. A total of 22 patients underwent selective clamping partial nephrectomy with the application of indocyanine green (ICG). Out of this cohort, a matched-pair analysis for R.E.N.A.L. nephrometry parameter was employed for 15 exactly matching partners. Demographic, surgical, pathological and kidney function data were collected for the initial cohort, and matched-pair comparison was made between the subgroups retrospectively. Robot-assisted partial nephrectomy without clamping of the hilum was possible in 21 patients in 1 patient, main artery clamping was necessary due to bleeding. Mean clinical tumor size was 37.7 mm. Mean selective clamping ischemia time was 11.6 mins with an estimated blood loss of 347 ml. No intra-operative complications occurred, and post-operative complications (n = 4), including 2 major urological (urinoma, late-onset acute hemorrhage) complications, were found. There were no side effects of ICG administration. Matched-pair analysis for 15 patients showed similar demographic and surgical data without any significant differences in tumor characteristics. Comparing short-term renal function outcomes, significantly decreased estimated glomerular filtration rate reduction in the selective clamping group with an absolute loss of 5.1 versus 16.1 ml/min in the global ischemia cohort (p = 0.045) could be observed. The authors concluded that robot-assisted partial nephrectomy with selective clamping of the tumor feeding vascular branches is a promising technique for reduced ischemic renal trauma. This may lead to improved kidney function preservation.

Press and Jaffer (2014) noted that coronary artery disease (CAD) is an inflammatory process that results in buildup of atherosclerosis, typically lipid-rich plaque in the arterial wall. Progressive narrowing of the vessel wall and subsequent plaque rupture can lead to myocardial infarction and death. Recent advances in intra-vascular fluorescence imaging techniques have provided exciting coronary artery-targeted platforms to further characterize the molecular changes that occur within the vascular wall as a result of atherosclerosis and following coronary stent-induced vascular injury. These investigators summarized recent developments in catheter-based imaging of coronary arterial-sized vessels focusing on 2-dimensional NIRF molecular imaging technology as an approach to identify inflammation and fibrin directly within coronary artery-sized vessels. The authors concluded that intravascular NIRF is anticipated to provide new insights into the in-vivo biology underlying high-risk plaques, as well as high-risks stents prone to stent re-stenosis or stent thrombosis.

Sarkaria et al (2014) stated that during esophagectomy, identification and preservation of the right gastro-epiploic vascular arcade are critical and may be challenging with minimally invasive approaches. These researchers assessed the use of near-infrared fluorescence imaging fluorescence angiography (NIFI-FA) during robotic-assisted minimally invasive esophagectomy (RAMIE) as an aid to visualize the gastric vasculature with mobilization. After intravenous administration of 10 mg of ICG, a robotic platform with NIR optical fluorescence capability was used to examine the gastric vasculature in patients undergoing RAMIE. A total of 30 (71 %) of 42 patients undergoing RAMIE were assessed using NIFI-FA during mobilization of the greater gastric curve and fundus 11 were excluded because the system was not available, and 1 was excluded because of documented allergy to iodinated contrast. The median time from ICG administration to detectable fluorescence was 37.5 seconds (range of 20 to 105 seconds). Near-infrared fluorescence imaging FA identified or confirmed termination of the vascular arcade in all 30 cases. Subjectively, NIFI-FA often identified otherwise unvisualized small transverse vessels between the termination of the vascular arcade and the first short gastric artery, as well as between the short gastric arteries. Identification and/or confirmation of the vascular arcade position during mobilization of the greater curve/omentum were also aided by NIFI-FA. The authors concluded that although there are limitations to the current technology, NIFI-FA may be a useful adjunct to confirm and identify the position of gastro-epiploic vessels, allow for safer and more confident dissections during gastric mobilization, as well as potentially decrease serious intra-operative vascular misadventures.

Ma et al (2014) stated that pathological angiogenesis is crucial in tumor growth, invasion and metastasis. Previous studies demonstrated that the vascular endothelial growth inhibitor (VEGI), a member of the tumor necrosis factor super-family, can be used as a potent endogenous inhibitor of tumor angiogenesis. Molecular probes containing the asparagine-glycine-arginine (NGR) sequence can specifically bind to CD13 receptor, which is over-expressed on neovasculature and several tumor cells. Near-infrared fluorescence optical imaging for targeting tumor vasculature offers a non-invasive method for early detection of tumor angiogenesis and efficient monitoring of response to anti-tumor vasculature therapy. These researchers developed a new NIRF imaging probe on the basis of an NGR-VEGI protein for the visualization of tumor vasculature. The NGR-VEGI fusion protein was prepared from prokaryotic expression, and its function was characterized in-vitro. The NGR-VEGI protein was then labeled with a Cy5.5 fluorophore to afford Cy5.5-NGR-VEGI probe. Using the NIRF imaging technique, these investigators visualized and quantified the specific delivery of Cy5.5-NGR-VEGI protein to subcutaneous HT-1080 fibrosarcoma tumors in mouse xenografts. The Cy5.5-NGR-VEGI probe exhibited rapid HT-1080 tumor targeting, and highest tumor-to-background contrast at 8 hours post-injection (pi). Tumor specificity of Cy5.5-NGR-VEGI was confirmed by effective blocking of tumor uptake in the presence of unlabeled NGR-VEGI (20 mg/kg). Ex-vivo NIRF imaging further confirmed in-vivo imaging findings, demonstrating that Cy5.5-NGR-VEGI displayed an excellent tumor-to-muscle ratio (18.93 ± 2.88) at 8 hours pi for the non-blocking group and significantly reduced ratio (4.92 ± 0.75) for the blocking group. The authors concluded that Cy5.5-NGR-VEGI provided highly sensitive, target-specific, and longitudinal imaging of HT-1080 tumors. They stated that as a novel theranostic protein, Cy5.5-NGR-VEGI has the potential to improve cancer treatment by targeting tumor vasculature.

Cornelissen and colleagues (2018) stated that NIRF imaging technique, after administration of contrast agents with fluorescent characteristics in the near-infrared (700 to 900 nm) range, is considered to possess great potential for the future of plastic surgery, given its capacity for peri-operative, real-time anatomical guidance and identification. These investigators provided a comprehensive literature review concerning current and potential future applications of NIRF imaging in plastic surgery, thereby guiding future research. A systematic literature search was performed in databases of Cochrane Library CENTRAL, Medline, and Embase (last search October 2017) regarding NIRF imaging in plastic surgery. Identified articles were screened and checked for eligibility by 2 authors independently. A total of 48 selected studies included 1,166 animal/human subjects in total NIRF imaging was described for a variety of (pre)clinical applications in plastic surgery 32 articles used NIRF angiography, i.e., vascular imaging after intravenous dye administration 10 articles reported on NIRF lymphography after subcutaneous dye administration. Although currently most applied, general protocols for dosage and timing of dye administration for NIRF angiography and lymphography are still lacking 3 articles applied NIRF to detect nerve injury, and another 3 studies described other novel applications in plastic surgery. The authors concluded that future standard implementation of novel intra-operative optical techniques, such as NIRF imaging, could significantly contribute to peri-operative anatomy guidance and facilitate critical decision-making in plastic surgical procedures. They stated that further investigation (i.e., large multi-center randomized controlled trials [RCTs]) is needed to establish the true value of this innovative surgical imaging technique in standard clinical practice and to aid in forming consensus on protocols for general use.

Esposito and colleagues (2020) stated that NIRF imaging with ICG has been recently adopted in pediatric minimally invasive surgery (MIS) in order to improve intra-operative visualization of anatomic structures and facilitate surgery. These researchers reported their preliminary experience using ICG technology in pediatric urology using laparoscopy and robotics. ICG technology was adopted in 57 laparoscopic or robotic urological procedures performed in the authors’ unit over a 24-month period: 41 (38 laparoscopic and 3 robotic) left varicocele repairs with intra-operative lymphography and 16 renal procedures (12 laparoscopic and 4 robotic) including 9 partial nephrectomies, 3 nephrectomies and 4 renal cyst deroofings. The ICG solution was injected intravenously in renal procedures or into the testis body in case of varicocele repair. Regarding the timing of the administration, the ICG injection was performed intra-operatively in all cases and allowed the visualization of the anatomic structures in a matter of 30 to 60 s. The dosage of ICG was 0.3 mg/ml/kg in all indications. All procedures were completed laparoscopically or robotically without conversions. No adverse and allergic reactions to ICG and other complications occurred post-operatively. This study described for the 1st time in pediatric urology that ICG-guided NIRF imaging may be helpful in laparoscopic and robotic procedures. In case of varicocele repair, ICG-enhanced fluorescence allowed to perform a lymphatic-sparing procedure and avoided the risk of post-operative hydrocele. In case of partial nephrectomy, ICG-guided NIRF was helpful to visualize the vascularization of the non-functioning moiety, identify the dissection plane between the 2 moieties and check the perfusion of the residual parenchyma after resection of the non-functioning pole. In case of renal cyst deroofing, ICG-guided NIRF aided to identify the avascular cyst dome and to guide its resection. No real benefits of using ICG-enhanced fluorescence were observed during nephrectomy. The authors concluded that their preliminary experience confirmed the safety and efficacy of ICG technology in pediatric urology and highlighted its potential advantages as adjunctive surgical technology in patients undergoing laparoscopic or robotic urological procedures. These researchers noted that the use of NIRF was also cost-effective as no added costs were required except for the ICG dye (cost 40 Euro per bottle). The most common and useful applications in pediatric urology included varicocele repair, partial nephrectomy and renal cyst deroofing. The main limitation was the specific equipment needed in laparoscopy, that is not available in all centers whereas the robot is equipped with the Firefly software for NIRF.

Detection of Ovarian Cancer Metastases

Tummers et al (2015) noted that in ovarian cancer, 2 of the most important prognostic factors for survival are completeness of staging and completeness of cytoreductive surgery (CRS). Therefore, intra-operative visualization of tumor lesions is of great importance. Pre-clinical data already demonstrated tumor visualization in a mouse-model using NIRF imaging and ICG as a result of enhanced permeability and retention (EPR). These researchers determined the feasibility of intra-operative ovarian cancer metastases imaging using NIRF imaging and ICG in a clinical setting. A total of 10 patients suspected of ovarian cancer scheduled for staging or CRS were included. Patients received 20 mg ICG intravenously after opening the abdominal cavity. The mini-FLARE NIR fluorescence imaging system was used to detect NIRF lesions. These investigators reported that 6 out of 10 patients had malignant disease of the ovary or fallopian tube, of which 2 had metastatic disease outside the pelvis 8 metastatic lesions were detected in these 2 patients, which were all NIR fluorescent. However, 13 non-malignant lesions were also NIR fluorescent, resulting in a false-positive rate of 62 %. There was no significant difference in tumor-to-background ratio between malignant and benign lesions (2.0 versus 2.0 p = 0.99). The authors concluded that this was the first clinical trial demonstrating intra-operative detection of ovarian cancer metastases using NIRF imaging and ICG. Despite detection of all malignant lesions, a high false-positive rate was observed. Therefore, they stated that NIRF imaging using ICG based on the EPR effect is not satisfactory for the detection of ovarian cancer metastases.

Intra-Operative Anatomy Navigation during Minimally Invasive Surgery

Schols et al (2015) stated that NIRF imaging, using contrast agents with fluorescent characteristics in the near-infrared (NIR: 700 to 900 nm) window, is considered to possess great potential for clinical practice in the future of minimally invasive surgery (MIS), given its capacity for intra-operative, real-time anatomical navigation, and identification. These researchers provided an overview of the literature concerning the current and potential future applications of fluorescence imaging in supporting anatomical guidance during MIS, and thereby guiding future research. A systematic literature search was performed in the PubMed and Embase databases. All identified articles were screened and checked for eligibility by 2 authors. In addition, literature was sought by screening references of eligible articles. After administration of a fluorescent dye (e.g., ICG), NIRF imaging can be helpful to improve the visualization of vital anatomical structures during MIS. Extra-hepatic bile ducts, arteries, ureters, sentinel lymph nodes, and lymph vessels have successfully been identified using NIRF imaging. A uniform approach regarding timing and route of dye administration has not yet been established. Optimization of both imaging systems and fluorescent dyes is needed to improve current shortcomings. New pre-clinical dyes are considered for optimization of NIRF imaging. The authors concluded that future implementation of new intra-operative optical methods, such as NIRF, could significantly contribute to intra-operative anatomy navigation and facilitate critical decision-making in MIS. Moreover, they stated that further research (i.e., large multi-center randomized controlled trials) is needed to establish the true value of this innovative optical imaging technique in standard clinical practice.

Lymphatic Imaging in Lymphangiomatosis/Klippel-Trenaunay Syndrome

Rasmussen et al (2015) stated that lymphangiomatosis is a rare disorder of the lymphatic system that can impact the dermis, soft tissue, bone, and viscera and can be characterized by lymphangiomas, swelling, and chylous discharge. Whether disordered lymphangiogenesis in lymphangiomatosis affects the function and anatomy of the entire systemic lymphatic circulation or is localized to specific sites is not fully known. These researchers reported the case of a 35-year old Caucasian female diagnosed with whole-body lymphangiomatosis at 2 months of age and who continued to present with progressive disease was imaged with NIRF lymphatic imaging. While the peripheral lymphatics in the extremities appeared largely normal compared to prior studies, these investigators observed tortuous lymphatic vessels, fluorescence drainage from the peripheral lymphatics into lymphangiomas, and extensive dermal lymphatics in the left thigh and inguinal regions where the subject had previously had surgical assaults, potentially indicating defective systemic lymphangiogenesis. The authors concluded that further research into anatomical and functional lymphatic changes associated with the progression and treatment of lymphangiomatosis could aid in understanding the pathophysiology of the disease as well as point to treatment strategies.

Rasmussen and colleagues (2017) noted that the relationship between lymphatic and venous malformations in Klippel-Trenaunay syndrome is difficult to assess. These investigators described NIRF lymphatic imaging to assess the lymphatics of a subject with a large port-wine stain and right leg edema. Although lymphatic vessels in the medial, affected knee appeared dilated and perhaps tortuous, no definitive abnormal lymphatic pooling or propulsion was observed. The lymphatics in the affected limb were well defined but less numerous than in the contralateral limb, and active, contractile function was observed in all vessels. The authors concluded that NIRF lymphatic imaging enabled the clinical assessment of lymphatics in lympho-venous malformations. These preliminary findings need to be validated by well-designed studies.

Furthermore, an UpToDate review on "Klippel-Trenaunay syndrome: Clinical manifestations, diagnosis, and management" (Frieden and Chu, 2017) does not mention NIRF imaging as a management tool.

Mapping of Microvascular Circulation in Ischemic Diseases

Namikawa and colleagues (2015) noted that NIRF imaging has better tissue penetration, allowing for the effective rejection of excitation light and detection deep inside organs. Indocyanine green generates NIRF after illumination by an NIR ray, enabling real-time intra-operative visualization of superficial lymphatic channels and vessels transcutaneously. The HyperEye Medical System (HEMS) can simultaneously detect NIR rays under room light to provide color imaging, which enables visualization under bright light. Thus, NIRF imaging using ICG can provide for excellent diagnostic accuracy in detecting SLNs in cancer and microvascular circulation in various ischemic diseases, to assist surgeons with intra-operative decision-making. Including HEMS in this system could further improve the SLN mapping and intra-operative identification of blood supply in reconstructive organs and ischemic diseases, making it more attractive than conventional imaging. Moreover, the development of new laparoscopic imaging systems equipped with NIR will allow fluorescence-guided surgery in a minimally invasive setting. The authors concluded that future directions, including the conjugation of NIR fluorophores to target specific cancer markers might be realistic technology with diagnostic and therapeutic benefits.

Mapping of Sentinel Lymph Nodes in Endometrial Cancer

In a pilot study, Plante and associates (2015) reported their initial experience with ICG for sentinel lymph node (SLN) mapping in cervical and endometrial cancer using a new endoscopic fluorescence imaging system. These researchers reviewed all patients who underwent primary surgery for early-stage endometrial and cervical carcinoma with SLN mapping using fluorescence imaging followed by pelvic lymphadenectomy from February to July 2014. Intra-cervical injection of ICG at 3 and 9 o'clock was performed in all cases SLNs were ultra-staged on final pathology. Sensitivity and specificity values were calculated. A total of 50 patients were included in the study (42 endometrial and 8 cervical cancers). The median age was 62 (24 to 88) years and median BMI was 29 (19 to 56). The median SLN count was 3.1 (0 to 7) and median lymph node count was 15 (2 to 37). The overall and bilateral detection rate was 96 % (48/50) and 88 % (44/50). Positive SLNs were identified in 22 % of patients (11/50), including 8 isolated tumor cells (ITC), 2 micro-metastasis and 1 macro-metastasis. There was 1 side-specific false negative case. Sensitivity, specificity and NPV were 93.3 %, 100 % and 98.7 %, per side, respectively. Para-aortic node dissection was performed in 22 % of cases. Two had para-aortic node metastasis both in patients with positive pelvic SLN. There were no allergic reactions to the ICG. The authors concluded that based on their experience in this pilot study, NIRF imaging with ICG is an excellent and safe tracer modality for SLN mapping with a very high overall (96 %) and bilateral (88 %) detection rate. The findings of this pilot study need to be validated by well-deigned studies.

An UpToDate review on "Endometrial carcinoma: Pretreatment evaluation, staging, and surgical treatment" (Plaxe, 2015) states that "One of the most important prognostic factors for endometrial carcinoma is the presence of extrauterine disease, particularly pelvic and paraaortic lymph node metastases. The approach to lymph node assessment is controversial, particularly in women presumed to have early stage disease …. Sentinel lymph node biopsy for endometrial carcinoma is still investigational. A meta-analysis of 26 studies including 1,101 sentinel node procedures found a sensitivity of 93 % for the detection of lymph node metastases in women with endometrial carcinoma. According to the sentinel lymph node hypothesis, tumor cells migrate from a primary tumor and colonize one or a few lymph nodes (i.e., the sentinel lymph node) before involving other lymph nodes. Peritumoral injection of a dye or tracer permits identification of a sentinel lymph node in most patients, and its status accurately predicts the status of the remaining regional nodes. The site of injection of the tracer for endometrial carcinoma is controversial. Studies have evaluated cervical, subserosal, and hysteroscopically-guided endometrial injection. The meta-analysis of 26 studies described above found that pericervical injection was associated with a significantly increased rate of detecting any sentinel node and that hysteroscopic injection was associated with a significantly decreased detection rate". This review does not mention near-infrared fluorescence imaging as a management tool.

Furthermore, National Comprehensive Cancer Network’s clinical practice guideline on "Endometrial carcinoma" (Version 2.2015) states that "The role of SLN mapping is currently being evaluated. No prospective randomized trials have been reported that evaluated this technique in endometrial cancer".

Diagnosis of Rheumatoid Arthritis

Krohn and colleagues (2015) stated that near-infrared fluorescence optical imaging (FOI) is a novel imaging technology in the detection and evaluation of different arthritides. Fluorescence optical imaging was validated in comparison to magnetic resonance imaging (MRI), grey-scale ultrasonography (GSUS), and power Doppler ultrasonography (PDUS) in patients with early rheumatoid arthritis (RA). Hands of 31 patients with early RA were examined by FOI, MRI, and US. In each modality, synovitis of the wrist, metacarpophalangeal joints (MCP) 2-5, and proximal interphalangeal joints (PIP) 2-5 were scored on a 4-point scale (0 to 3). Sensitivity and specificity of FOI were analyzed in comparison to MRI and US as reference methods, differentiating between 3 phases of FOI enhancement (P1-P3). Intraclass correlation coefficients (ICC) were calculated to evaluate the agreement of FOI with MRI and US. A total of 279 joints (31 wrists, 124 MCP and 124 PIP joints) were evaluated. With MRI as the reference method, overall sensitivity/specificity of FOI was 0.81/0.00, 0.49/0.84, and 0.86/0.38 for wrist, MCP, and PIP joints, respectively. Under application of PDUS as reference, sensitivity was even higher, while specificity turned out to be low, except for MCP joints (0.88/0.15, 0.81/0.76, and 1.00/0.27, respectively). P2 appeared to be the most sensitive FOI phase, while P1 showed the highest specificity. The best agreement of FOI was shown for PDUS, especially with regard to MCP and PIP joints (ICC of 0.57 and 0.53, respectively), while correlation with MRI was slightly lower. The authors concluded that FOI remains an interesting diagnostic tool for patients with early RA, although this study revealed limitations concerning the detection of synovitis. They stated that further research is needed to evaluate its full diagnostic potential in rheumatic diseases.

Evaluation of Coronary Atherosclerosis

Verjans and associates (2016) examined if ICG-enhanced NIRF imaging can illuminate high-risk histologic plaque features of human carotid atherosclerosis, and in coronary atheroma of living swine, using intra-vascular NIRF- OCT imaging. A total of 8 patients were enrolled in the BRIGHT-CEA (Indocyanine Green Fluorescence Uptake in Human Carotid Artery Plaque) trial 5 patients were injected intravenously with ICG 99 ± 25 mins before clinically indicated carotid endarterectomy 3 saline-injected endarterectomy patients served as control subjects. Excised plaques underwent analysis by intra-vascular NIRF-OCT, reflectance imaging, microscopy, and histopathology. Next, following ICG intravenous injection, in-vivo intra-coronary NIRF-OCT and intra-vascular ultrasound imaged 3 atheroma-bearing coronary arteries of a diabetic, cholesterol-fed swine. Indocyanine green was well-tolerated no adverse clinical events occurred up to 30 days post-injection. Multi-modal NIRF imaging including intra-vascular NIRF-OCT revealed that ICG accumulated in all endarterectomy specimens. Plaques from saline-injected control patients exhibited minimal NIRF signal. In the swine experiment, intra-coronary NIRF-OCT identified ICG uptake in all intra-vascular ultrasound-identified plaques in-vivo. On detailed microscopic evaluation, ICG localized to plaque areas exhibiting impaired endothelial integrity, including disrupted fibrous caps, and within areas of neovascularization. Within human plaque areas of endothelial abnormality, ICG was spatially related to localized zones of plaque macrophages and lipid, and, notably, intra-plaque hemorrhage. The authors concluded that the findings of this study demonstrated that ICG targets human plaques exhibiting endothelial abnormalities and provided new insights into its targeting mechanisms in clinical and experimental atheroma. They stated that intra-coronary NIRF-OCT of ICG may offer a novel, clinically translatable approach to image pathobiological aspects of coronary atherosclerosis.

Osborn and colleagues (2017) stated that metabolic and molecular imaging continues to advance the understanding of vascular disease pathophysiology. At present, 18F-FDG PET imaging is the most widely used clinical tool for metabolic and molecular imaging of atherosclerosis. However, novel nuclear tracers and intravascular optical NIRF imaging catheters are emerging to assess new biologic targets in-vivo and in coronary arteries. This review highlighted current metabolic and molecular imaging clinical and near-clinical applications within atherosclerosis and venous thrombo-embolism (VTE), and examined the potential for metabolic and molecular imaging to affect patient-level risk prediction and disease treatment. The authors stated that intravascular NIRF molecular imaging showed promise for high-resolution molecular imaging and can be integrated with intravascular US or OCT, strengthening the ability to provide comprehensive molecular-structural imaging of atherosclerosis and stent biology. However, NIRF imaging is in its infancy for clinical translation and will require clinical outcome studies to determine its value. Given its invasive requirement, NIRF imaging will likely be used to further stratify patients already undergoing percutaneous coronary intervention (PCI) for acute coronary syndrome (ACS) or stable angina.

Assessment of Liver Function

Narasaki and colleagues (2017) stated that post-operative liver failure is a serious complication after major hepatectomy, and peri-operative prediction of its incidence using current technology is still very difficult. Near-infrared fluorescence imaging allows quantitative assessment of the fluorescent signal from ICG in regions of interest on the liver surface. This method might offer a new promising modality for evaluating regional liver reserve. However, data are lacking regarding the relationship between liver function and fluorescent signals on the liver surface after intravenous ICG injection. This study was conducted to obtain the data necessary to apply NIR fluorescence imaging as a modality for measuring liver function. This study included 16 patients who underwent open hepato-pancreatobiliary surgery between March 2011 and March 2012. After laparotomy, ICG was injected intravenously at 2.5 mg/L of liver volume, then the fluorescence intensity (FI) and signal-to-background ratio (SBR) in the lateral segment of the liver were assessed for 15 minutes. Intra-operative blood samples were also obtained to measure the plasma clearance rate of ICG (ICGK). Correlations between ICGK, liver volume, and SBR, as well as between ICGK, liver volume, and rate of change of FI were analyzed. The experimental procedure was performed in all 16 patients. The FI of the liver increased rapidly after ICG injection, then became more gradual, reaching a near-plateau after 15 minutes. A significant correlation was seen between ICGK and the rate of change of FI up to 15 minutes (|rS| = 0.5725, p < 0.05). The authors concluded that this was the first report to show a relationship between liver function and fluorescent signals on the liver surface after intravenous ICG injection. They stated that intra-operative NIR fluorescence imaging with ICG may be useful as a new method for assessing liver function.

Guidance of Surgery for Intracranial Meningioma

Lee and colleagues (2018) stated that meningiomas are the most common primary tumor of the central nervous system. Complete resection can be curative, but intra-operative identification of dural tails and tumor remnants poses a clinical challenge. Given data from pre-clinical studies and previous clinical trials, the authors proposed a novel method of localizing tumor tissue and identifying residual disease at the margins via pre-operative systemic injection of a NIR fluorescent contrast dye. This technique, what the authors call "second-window ICG (SWIG)", relies on the visualization of ICG approximately 24 hours after intravenous injection. A total of 18 patients were prospectively identified and received 5 mg/kg of SWIG the day prior to surgery. An NIR camera was used to localize the tumor prior to resection and to inspect the margins following standard resection. The SBR of the tumor to the normal brain parenchyma was measured in triplicate. Gross tumor and margin specimens were qualitatively reported with respect to fluorescence. Neuropathological diagnosis served as the reference gold standard to calculate the sensitivity and specificity of the imaging technique 18 patients harbored 15 World Health Organization (WHO) Grade I and 3 WHO Grade II meningiomas. Near-infrared visualization during surgery ranged from 18 to 28 hours (mean of 23 hours) following SWIG infusion 14 of the 18 tumors demonstrated a markedly elevated SBR of 5.6 ± 1.7 as compared with adjacent brain parenchyma 4 of the 18 patients showed an inverse pattern of NIR signal (i.e., stronger in the adjacent normal brain than in the tumor (SBR 0.31 ± 0.1)). The best predictor of inversion was time from injection, as the patients who were imaged earlier were more likely to demonstrate an appropriate SBR. The SWIG technique demonstrated a sensitivity of 96.4 %, specificity of 38.9 %, positive predictive value (PPV) of 71.1 %, and a negative predictive value (NPV) of 87.5 % for tumor. The authors concluded that systemic injection of NIR SWIG the day before surgery can be used to visualize meningiomas intra-operatively. They noted that intra-operative NIR imaging provided higher sensitivity in identifying meningiomas than the unassisted eye. In this study, 14 of the 18 patients with meningioma demonstrated a strong SBR compared with adjacent brain. These researchers stated that in the future, reducing the time interval from dye injection to intra-operative imaging may improve fluorescence at the margins, although this approach requires further investigation.

Intra-Operative Imaging of Lung Cancer / Lung Metastases/Mesothelioma

Keating and associates (2017a) stated that complete tumor resection is the most important predictor of patient survival with non-small cell lung cancer (NSCLC). Methods for intra-operative margin assessment after lung cancer excision are lacking. These researchers evaluated NIR intra-operative imaging with a folate-targeted molecular contrast agent (OTL0038) for the localization of primary lung adenocarcinomas, lymph node sampling, and margin assessment. A total of 10 dogs with lung cancer underwent either video-assisted thoracoscopic surgery or open thoracotomy and tumor excision after an intravenous injection of OTL0038. Lungs were imaged with an NIR imaging device both in-vivo and ex-vivo. The wound bed was re-imaged for retained fluorescence suspicious for positive tumor margins. The tumor SBR was measured in all cases. Next, 3 human patients were enrolled in a proof-of-principle study. Tumor fluorescence was measured both in-situ and ex-vivo. All canine tumors fluoresced in-situ (mean Fluoptics SBR, 5.2 [range of 2.7 to 8.1] mean Karl Storz SBR 1.9 [range of 1.4 to 2.6]). In addition, the fluorescence was consistent with tumor margins on pathology 3 positive lymph nodes were discovered with NIR imaging. Also, a positive retained tumor margin was discovered upon NIR imaging of the wound bed. Human pulmonary adenocarcinomas were also fluorescent both in-situ and ex-vivo (mean SBR, greater than 2.0). The authors concluded that NIR imaging can identify lung cancer in a large-animal model. In addition, NIR imaging can discriminate lymph nodes harboring cancer cells and also bring attention to a positive tumor margin. In humans, pulmonary adenocarcinomas fluoresce after the injection of the targeted contrast agent.

Keating and colleagues (2017b) noted that pulmonary metastasectomy is widely accepted for many tumor types because it may prolong survival and potentially cure some patients. However, intra-operative localization of pulmonary metastases can be technically challenging. These researchers proposed that intra-operative NIR molecular imaging can be used as an adjunct during disease localization. They inoculated 50 C57BL/6 mice with Lewis lung carcinoma (LLC) flank tumors. After flank tumor growth, mice were injected through the tail vein with ICG before operation, and intra-operative imaging was used to detect pulmonary metastases. On the basis of these experiments, these investigators enrolled 8 patients undergoing pulmonary metastasectomy into a pilot and feasibility clinical trial. Each patient received intravenous ICG 1 day before operation, followed by wedge or segmental resection. Samples were imaged on the back table with an NIR camera to confirm disease presence and margins. All murine and human tumors and margins were confirmed by pathologic examination. Mice had an average of 4 ± 2 metastatic tumors on both lungs, with an average size of 5.1 mm (interquartile range [IQR] 2.2 mm to 7.6 mm). Overall, 200 of 211 (95 %) metastatic deposits were markedly fluorescent, with a mean tumor-to-background ratio (TBR) of 3.4 (IQR 3.1 to 4.1). The remaining tumors had a TBR below 1.5. In the human study, intra-operative NIR imaging identified 6 of the 8 pre-operatively localized lesions. Intra-operative back table NIR imaging identified all metastatic lesions, which were confirmed by pathologic examination. The average tumor size was 1.75 ± 1.4 cm, and the mean ex-vivo TBR was 3.3 (IQR 3.1 to 3.7). Pathologic examination demonstrated melanoma (n = 4), osteogenic sarcoma (n = 2), renal cell carcinoma (n = 2), chondrosarcoma (n = 1), leiomyosarcoma (n = 1), and colorectal carcinoma (n = 1). The authors concluded that systemic ICG identified subcentimeter tumor metastases to the lung in murine models, and this work provided proof of principle in humans. They stated that future research is focused on improving depth of penetration into the lung parenchyma.

Furthermore, National Comprehensive Cancer Network’s clinical practice guideline on "Non-small cell lung cancer" (Version 8.2017) and "Small cell lung cancer" (Version 3.2017) do not mention near-infrared fluorescence imaging as a management tool.

Kennedy and colleagues (2017) noted that although difficult to achieve, complete resection of malignant pleural mesothelioma is paramount to improving patient survival. Surgeons have traditionally been limited to using visual inspection and manual palpation to locate and remove cancerous tissue. However, intra-operative molecular imaging (IMI) is a promising new technology in surgery. Molecular imaging utilizes a fluorescent tracer that selectively accumulates in cancer cells. An imaging device is then used to detect and augment the fluorescent signal emitted from the fluorescent cancer cells. Investigators had demonstrated that molecular imaging with either ICG or a folate receptor alpha (FRα) targeted fluorophore can accurately identify a number of intra-thoracic malignancies. Early studies of intra-operative imaging have suggested its efficacy for malignant pleural mesothelioma. In a murine model of mesothelioma, intra-operative imaging was found to have sensitivity of 87 % and specificity of 83 %. In a pilot human study, 8 patients with biopsy-proven epithelial malignant pleural mesothelioma were administered 5 mg/kg of intravenous ICG injection 24 hours prior to resection. The following day, a NIR imaging device was used to detect tumor fluorescence intra-operatively. After what was believed to be complete tumor excision, the wound bed was re-imaged for residual fluorescence indicative of retained tumor. When residual fluorescence was detected, additional tissue was resected, if feasible, and specimens were sent for pathologic correlation. In all cases, intra-operative fluorescence localized to mesothelioma deposits which were confirmed on final pathology. Following resection, fluorescence was confirmed ex-vivo with a mean TBR of 3.2 (IQR: 2.9 to 3.4). The authors concluded that it is hoped that this technology will improve outcomes for mesothelioma patients by allowing for a more complete oncologic resection.

Localization of Brain Metastases

Lee and colleagues (2017) noted that approximately 100,000 brain metastases are diagnosed annually in the United States. These researchers have pioneered a novel technique, "SWIG", which allows for real-time intra-operative visualization of brain metastasis through normal brain parenchyma and intact dura. A total of 13 patients with intra-parenchymal brain metastases were administered ICG at 5mg/kg the day prior to surgery. A NIR capable camera was used intra-operatively to identify the tumor and to inspect surgical margins. Neuropathology was used to assess the accuracy and precision of the fluorescent dye for identifying tumor. ICG was infused at 24.7 ± 3.45 hours before visualization. All 13 metastases fluoresced with an average SBR of 6.62. The SBR with the dura intact was 67.2 % of the mean SBR once the dura was removed. The NIR signal could be visualized through normal brain parenchyma up to 7 mm. For the 39 total specimens, the mean SBR for tumor specimens (n = 28) was 6.9 whereas the SBR for non-tumor specimens (n = 11) was 3.7. The sensitivity, specificity, PPV and NPV of NIR imaging for tumor was 96.4 %, 27.3 %, 77.1 %, and 75.0 %, respectively. The authors concluded that SWIG relied on the passive accumulation of dye in abnormal tumor tissue via the enhanced permeability and retention (EPR) effect. It provided strong NIR SBR, which can be utilized to localize tumors prior to dural opening. They stated that the use of SWIG for margin assessment remains limited by its lack of specificity (high false-positive rate) however, ongoing improvements in imaging parameters show great potential to reduce false-positives.

Delineation of the Ureters during Laparoscopy

Al-Taher and colleagues (2018) stated that iatrogenic ureteric injury remains a risk in laparoscopic pelvic procedures NIRF imaging is a promising new technique for enhanced intra-operative visualization of anatomical structures that could improve the safety of laparoscopic surgery. A new dye, IRDye 800-BK, has been developed for intra-operative visualization of the ureters using NIRF. The present study was a first evaluation of the performance of IRDye 800-BK for ureteric imaging during NIRF laparoscopy. This study consisted of 3 parts: real-time in-vivo NIRF imaging using IRDye 800-BK in pigs during laparoscopic surgery, ex-vivo NIRF imaging of freshly explanted pig ureters and ex-vivo NIRF imaging of explanted human ureters. In all animals, both left and right ureters were visualized throughout the laparoscopic procedure for 120 mins, with the best results at a dose of 0.15 mg dye per kg bodyweight NIRF imaging was successful in all human and porcine ureters studied, with a range of dye concentrations. The authors concluded that this novel dye enabled visualization of the ureters NIRF imaging with this dye appeared a valuable addition to conventional white light laparoscopy. Moreover, they stated that further studies are needed to determine if it can become a worthwhile addition to improve clinical practice.

The authors stated that a drawback of the ex-vivo experiments is that 2 influences were studied at the same time: dye concentration and wall thickness. Ideally, different concentrations of dye should be tested in the same ureters, and the same concentration in different ureters. The first of these types of experiment was not feasible, because the fluorescent signal was retained in the ureter wall. Such an experiment could therefore be performed only using artificial material. The second experiment has not yet been undertaken. These researchers noted that despite the promising results, the present findings must be interpreted with caution. Owing to the limited availability of pigs and ureters, it was not possible to study enough ureters for solid statistical conclusions to be drawn. Another drawback was that concentrations of dye in the urine were not measured. This required availability of the structural formula of the dye and a method for such measurement. These were not available to the authors in this early phase of development and application of the dye. These investigators also stated that it was disappointing in the ex-vivo study that even the smallest layer of fat covering the ureter prevented a decent signal from being obtained. It is known that penetration of the NIRF signal is limited to approximately 10 mm NIRF imaging with a stronger dye or with optimized equipment was hoped to enhance such penetration. The present experiment showed that the signal may be improved with use of a better dye, but that this did not affect depth penetration per se. In the in-vivo study, nevertheless, the porcine ureters could be identified clearly without any manipulation or dissection of the overlying tissues. This suggested that IRDye 800‐BK has the potential to detect the ureter in spite of the overlying peritoneum. They stated that future studies should evaluate the maximum depth of penetration of the NIRF signal and the clinical value of this dye in human subjects.

Detection and Resection of Colorectal Neoplasia

Jones and colleagues (2018) used a tumor-targeting, NIRF peptide to evaluate early detection and to guide surgical removal of polyps in a genetically engineered rat model of spontaneous colorectal cancer (CRC). This peptide, LS301, was conjugated to Cy7.5 and applied topically to the colon of adenoma-bearing Pirc rats 10 minutes after administration, rats underwent targeted NIR laser colonoscopy. Rats were also evaluated by white light colonoscopy and narrow-band imaging, for comparison to the NIR technique. Unlike white light and narrow-band colonoscopy, NIR imaging detected unexpected flat lesions in young Pirc rats NIR imaging was also used to assess resection margins after electro-cauterization of polyps. Tumor margins remained negative at 5 weeks post-surgery, demonstrating successful polypectomy. The authors concluded that the findings of this study showed that NIR-targeted colonoscopy is an attractive strategy to improve screening for and resection of colorectal neoplasia. These researchers stated that a drawback of this study was that they employed topical application of Cy7.5-LS301 in the rat model. They chose this route of administration to be consistent with the technique Charanya et al used for NIR colonoscopy of tumor-bearing mice. However, topical application of an NIR peptide is not clinically practical, due to the large quantity of the imaging agent that would be needed. These investigators have now established an optimal intravenous injected dose in Pirc rats and will use this method of administration for future studies. Moreover, these researchers stated that they have not yet tested their ability to detect recurrent disease in the rat model and they plan to evaluate the ability of the peptide to do so in longer term longitudinal studies.

Evaluation of Soft Tissue Viability to Guide Debridement in Trauma Surgery

In a case-report, Pruimboom and co-workers (2018) presented the use of NIRF imaging using ICG and its potential for the evaluation of soft tissue viability in a traumatic case. The authors stated that standard implementation of this novel imaging modality might decrease the number of surgical debridement procedures in complex traumatic wounds. Moreover, they stated that further clinical studies are needed to assess the appropriate timing of performing NIRF imaging and to obtain generalized quantification methods of NIRF images, hence determining a precise cut-off point. Consequently, the possible advantages of NIRF imaging in terms of cost-effectiveness in trauma surgery need to be determined.

Imaging of Matrix Metalloproteinase 2 Activity as a Biomarker of Vascular Remodeling in Arterio-Venous Fistulae

Nadolski and colleagues (2018) attempted to establish the capability of NIRF imaging for the detection of matrix metalloproteinase 2 (MMP-2) activity as a biomarker of vascular remodeling (VR) in arterio-venous fistulae (AVFs) in-vivo AVFs were created in the right groins of Wistar rats (n = 10), and sham procedures were performed in the contralateral groins. Fistulography via a left common carotid artery approach confirmed stenosis (greater than 50 %) in a subset of animals (n = 5) 4 weeks after AVF creation. After administration of MMP-2-activated NIRF probe, NIR imaging was performed in-vivo and ex-vivo of both the AVF and the sham-treated vessels to measure radiant efficiency of MMP-2-activated NIRF signal over background. Histologic analyses of AVF and sham-treated vessels were performed to measure VR defined as inward growth of the vessel caused by intimal thickening. AVFs demonstrated a significantly higher percentage increase in radiant efficiency over background compared with sham vessels (45.5 ± 56 % versus 16.1 ± 17.8 % p = 0.008). VR in AVFs was associated with increased thickness of neointima staining positively for MMP-2 (161.8 ± 45.5 μm versus 73.2 ± 36.7 μm p = 0.01). A significant correlation was observed between MMP-2 activity as measured by relative increase in radiant efficiency for AVFs and thickness of neointima staining positively for MMP-2 (p = 0.039). The authors concluded that NIRF imaging could detect increased MMP activity in remodeled AVFs compared with contralateral sham vessels MMP-2-activated NIRF signal correlated with the severity of intimal thickening. They stated that these findings suggested NIRF imaging of MMP-2 may be used as a biomarker of the vascular remodeling underlying stenosis.

Intra-Operative Detection of Hepatocellular Carcinoma and Needle Tract Implantation and Peritoneal Seeding after Radiofrequency Ablation

Nakamura and associates (2018) noted that radio-frequency ablation (RFA) for hepato-cellular carcinoma (HCC) is already fully established worldwide. Needle tract implantation and peritoneal seeding occasionally occur by RFA, and the prognosis of these cases is thought to be poor. In a single-case study, intra-operative real-time NIRF system by (ICG incidentally detected both needle tract implantation and peritoneal seeding. As the utility of this system for identification of implanted and disseminated lesions after RFA for HCC has not been widely reported, thee investigators reported a case of successful detection by real-time ICG-NIRF imaging and subsequent resection. A 76-year old man originally underwent medial sectionectomy for HCC in 2009. When repeated intra-hepatic recurrence occurred, he underwent RFA and transcatheter arterial chemo-embolization (TACE) for recurrent HCC twice at segment III and once at segment IV. In 2013, the second hepatectomy for recurrent HCC at segment VIII was performed. In 2016, he had recurrent HCC at segment III around a previous RFA and TACE scar therefore, left lateral sectionectomy was planned. ICG-NIRF system was used to observe a main intra-hepatic metastasis at segment III and to search for other tumors in the remnant liver. Although there was no signal on the surface of the remnant liver, tiny signals were observed in the abdominal wall and greater omentum. These tumors were on the needle tract of the previous RFA both lesions, therefore, were resected. These tumors were pathologically proven to be HCC metastases. The patient has had no recurrence 14 months after the last hepatectomy. The authors concluded that ICG-NIRF system might be helpful in the detection of not only intra-hepatic lesions but also needle tract implantations or peritoneal seeding. Moreover, they stated that RFA should be avoided in patients with high risk of needle tract implantation and peritoneal seeding. These preliminary findings need to be validated by well-designed studies.

The authors stated that ICG-NIRF system has some drawbacks. The system is restricted to detection of fluorescence for tumors 5 to 10 mm from the liver surface. There were also false-positive results for liver cysts and dysplastic tumors in severe liver cirrhosis. They stated that this system might be helpful in the detection of needle tract implantations or peritoneal seeding.

Intra-Operative Detection of Pancreatic Cancer and Metastases

Hoogstins and colleagues (2018) stated that NIRF is a promising novel imaging technique that can aid in intra-operative demarcation of pancreatic cancer (PDAC) and thus increase radical resection rates. In a phase-I clinical trial, these investigators evaluated the effectiveness SGM-101, a novel, fluorescent-labeled anti-carcinoembryonic antigen (CEA) antibody. The trial examined the tolerability and feasibility of intra-operative fluorescence tumor imaging using SGM-101 in patients undergoing a surgical exploration for PDAC. At least 48 hours before undergoing surgery for PDAC, 12 patients were injected intravenously with 5, 7.5, or 10 mg of SGM-101. Tolerability assessments were performed at regular intervals after dosing. The surgical field was imaged using the Quest NIR imaging system. Concordance between fluorescence and tumor presence on histopathology was studied. In this study, SGM-101 specifically accumulated in CEA-expressing primary tumors and peritoneal and liver metastases, allowing real-time intra-operative fluorescence imaging. The mean TBR was 1.6 for primary tumors and 1.7 for metastatic lesions. One false-positive lesion was detected (CEA-expressing intra-ductal papillary mucinous neoplasm) false-negativity was observed twice as a consequence of overlying blood or tissue that blocked the fluorescent signal. The authors concluded that the use of a fluorescent-labeled anti-CEA antibody was safe and feasible for the intra-operative detection of both primary PDAC and metastases. They stated that more prospective research is needed to determine the impact of this technique on clinical decision making and overall survival (OS).

Hybrid Near Infrared Fluorescence-Intravascular Ultrasound (NIRF-IVUS) System

  1. assessed a novel hybrid NIRF-intravascular ultrasound (NIRF-IVUS) system in coronary and peripheral swine arteries in-vivo
  2. evaluated simultaneous quantitative biological and morphological aspects of arterial disease.

Two 9-F/15-MHz peripheral and 4.5-F/40-MHz coronary NIRF-IVUS catheters were engineered to enable accurate co-registration of biological and morphological readings simultaneously in-vivo. A correction algorithm utilizing IVUS information was developed to account for the distance-related fluorescence attenuation due to through-blood imaging. Corrected NIRF (cNIRF)-IVUS was applied for in-vivo imaging of angioplasty-induced vascular injury in swine peripheral arteries and experimental fibrin deposition on coronary artery stents, and of atheroma in a rabbit aorta, revealing feasibility to intravascularly assay plaque structure and inflammation. The addition of ICG-enhanced NIRF assessment improved the detection of angioplasty-induced endothelial damage compared to stand-alone IVUS. In addition, NIRF detection of coronary stent fibrin by in-vivo cNIRF-IVUS imaging illuminated stent pathobiology that was concealed on stand-alone IVUS. Fluorescence reflectance imaging and microscopy of resected tissues corroborated with the in-vivo findings. The authors concluded that integrated cNIRF-IVUS enabled simultaneous co-registered through-blood imaging of disease related morphological and biological alterations in coronary and peripheral arteries in-vivo. Clinical translation of cNIRF-IVUS may significantly enhance knowledge of arterial pathobiology, leading to improvements in clinical diagnosis and prognosis, and aid to guide the development of new therapeutic approaches for arterial diseases.

Diagnosis of Peripheral Artery Disease

van den Hoven and colleagues (2019) noted that in the diagnosis of peripheral artery disease (PAD), the ankle-brachial index (ABI) plays an important role. However, results of the ABI are unreliable in patients with severe media sclerosis. Near-infrared (NIR) fluorescence imaging using ICG can provide information regarding tissue perfusion and has already been studied in oncologic, reconstructive, and cardiac surgery. For patients with PAD, this technique might give insight into skin perfusion and thereby guide treatment. These researchers carried out a systematic review of the literature on the use of NIR fluorescence imaging in patients with PAD. PubMed, Medline, Embase, and Cochrane were searched for articles and abstracts on the application of NIR fluorescence imaging using ICG as fluorescent dye in patients with PAD. The search strategy combined the terms "fluorescence", "ICG", or synonyms and "peripheral artery disease" or synonyms. The extracted data included fluorescence parameters and test characteristics for diagnosis of PAD. A total of 23 articles were found eligible for this review using 18 different parameters for evaluation of the fluorescence signal intensity. NIR fluorescence imaging was used for 4 main indications: diagnosis, quality control in re-vascularization, guidance in amputation surgery, and visualization of vascular structures. For the diagnosis of PAD, NIR fluorescence imaging yielded a sensitivity ranging from 67 % to 100 % and a specificity varying between 72 % and 100 %. Significant increases in multiple fluorescence parameters were found in comparing patients before and after re-vascularization. The authors concluded that NIR fluorescence imaging could be used for several indications in patients with PAD NIR fluorescence imaging appeared promising in diagnosis of PAD and guidance of surgeons in treatment, especially in patients in whom current diagnostic methods are not applicable. These researchers stated that further standardization is needed to reliably use this modality in patients with PAD.

Guidance for Sentinel Lymph Node Mapping in Gastric Cancer

Skubleny and associates (2018) noted that sentinel node navigation surgery (SNNS) for gastric cancer (GC) using infrared visualization of ICG is intriguing because it may limit operative morbidity. These investigators performed a meta-analysis on the diagnostic utility of ICG and infrared electronic endoscopy (IREE) or NIR fluorescent imaging (NIFI) for SNNS exclusively in GC. They carried out a search of electronic databases Medline, Embase, SCOPUS, Web of Science, and the Cochrane Library using search terms "gastric/stomach" and "tumor/carcinoma/cancer/neoplasm/adenocarcinoma/malignancy" and "indocyanine green" search was completed in May 2017. Articles were selected by 2 independent reviewers based on the following major inclusion criteria: diagnostic accuracy study design ICG was injected at tumor site IREE or NIFI was used for intra-operative visualization. A total of 327 titles or abstracts were screened. The quality of included studies was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 10 full text studies were selected. A total of 643 patients were identified with the majority of patients possessing T1 tumors (79.8 %). Pooled identification rate, diagnostic odds ratio (DOR), sensitivity (Sen), and specificity (Spe) were 0.99 (0.97 to 1.0), 380.0 (68.71 to 2101), 0.87 (0.80 to 0.93), and 1.00 (0.99 to 1.00), respectively. The summary receiver operator characteristic (ROC) for ICG + IREE/NIFI demonstrated a test accuracy of 98.3 %. Subgroup analysis found improved test performance for studies with low-risk QUADAS-2 scores, studies published after 2010 and submucosal ICG injection. IREE had improved DOR, Sen, and identification rate compared to NIFI. Heterogeneity among studies ranged from low (I2 less than 25 %) to high (I2 greater than 75 %). The authors concluded that they found encouraging results regarding the accuracy, DOR, and Spe of the test. The Sen was not optimal but may be improved by a strict protocol to augment the technique. These researchers stated that given the number and heterogeneity of studies, these findings must be viewed with caution.

In a meta-analysis, He and colleagues (2018) examined the diagnostic value of NIR or fluorescent ICG guided sentinel lymph node (SLN) mapping in GC. Clinical studies were retrieved from the electronic database PubMed, Embase, Medline, Web of science, and the Cochrane Library. Quality assessment was conducted by an adapted checklist of QUADAS-2. A bivariate mixed-effects model was used to pool the data. Evaluation of articles quality, analysis for publication bias, summary ROC (SROC) curves, and meta-regression were also performed. Subgroup analysis was used to explain the heterogeneities. A total of 13 clinical studies (971 patients) were included. The NIR or FI involved IREE, infrared ray laparoscopic system (IRLS), and FI system. Significant evidence of heterogeneity was found for Sen and Spe: I2 = 91.1 % and I2 = 98.2 %, respectively. The pooled SLN Sen, Spe, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and DOR were 0.94 (95 % CI: 0.80 to 0.99), 1.00 (95 % CI: 0.60 to 1.00), 34.0 (95 % CI: 9.25 to 125.29), 0.06 (95 % CI: 0.02 to 0.22), and 252.50 (95 % CI: 94.93 to 671.61), respectively. Area under curve (AUC) of SROC curve was 1.00 (95 % CI: 0.99 to 1.00), and the summary operating point (cut-off value) was SENS = 0.94 (95 % CI: 0.80 to 0.99) and SPEC = 1.00 (95 % CI: 0.60 to 1.00). Subgroup analysis showed that NIR imaging, imaging performed 20 mins after intra-operative injection, pre-operative injection (especially for FI imaging), stained with immunohistochemistry (IHC) (+hematoxylin-eosin [HE]), cT1 stage, submucosa injection (especially for cT1), mean number of SLN greater than or equal to 5, study size greater than 26 were associated with higher SLN sensitivity. In terms of ICG concentration, diluted ICG concentration that 0.5 mg/ml (compared with 5 mg/ml) in NIR imaging and 0.05 mg/ml (compared with 0.5 mg/ml) in FI system showed higher sensitivities. However, the differences in tumor diameter (less than or equal to 30 mm versus greater than 30 mm), gastrectomy methods (opening versus laparoscopy), lymphadenectomy methods (LBD versus pick-up), and publication year (in or after 2010 versus before 2010) did not achieve statistical significance. The authors concluded that ICG combined with NIR or FI guided SLN mapping was technically feasible for GC. Based on the small sample size evidence, the IREE and IRLS devices may have higher sensitivity than FI in current clinical studies and there may be an excessive ICG concentration used for current SLN mapping in GC. Moreover, these researchers stated that well-designed further studies with large sample size are needed to confirm the best procedure and suitable criteria.

Fluorescence Sentinel Lymph Node Mapping for Colorectal Cancer

Picchetto and associates (2020) noted that sentinel lymph node (SLN) mapping using NIRF imaging is a recent technique to improve nodal staging in several tumors. The presence of colo-rectal cancer (CRC) micro-metastases has recently been defined as N1 disease and no longer as N1mi, determining the need for adjuvant chemotherapy. In CRC, the reported rate of SLN micro-metastases detected by ultra-staging techniques is as high as 30 %. In a prospective study, these researchers presented the preliminary results of the sensitivity analysis of NIRF imaging for ex-vivo SLN mapping and the research of micro-metastases in CRC, in patients with node-negative disease (NND). On the specimen of 22 CRC patients, 1-ml of ICG (5 mg/ml) was injected submucosally around the tumor to identify SLNs. NND SLNs were further investigated with ultra-staging techniques. A total of 363 lymph nodes were retrieved (59 SLNs mean per case: 2.7). The detection, sensitivity and false-negative rate were 100 %, 100 % and 0 % respectively. Ultra-staging investigations showed no micro-metastases in the NND SLNs. The authors concluded that ex-vivo SLN fluorescence-based detection in CRC was confirmed to be easy to perform and reliable. In this preliminary report of an ongoing study, the SLN assay was congruent with the nodal status, as confirmed by histological investigations.

Night Vision versus Thermal Imaging

The Voyager spacecraft structure - schematic diagram.

By Voyager_spacecraft_structure.jpg: NASA derivative work: Camilo Sanchez (Voyager_spacecraft_struct

  • Used in night vision devices to observe animals or people using the phenomenon called infrared illumination. The observant will not know that they are being observed.
  • Used in astronomy to observe objects that are blurred and hidden by the interstellar dust. Infrared imaging process is used here.
  • Used in astronomical telescopes that are equipped with infrared sensors and these telescopes are used to detect distant planets that are in the dusty regions of space, as they cannot be viewed using a normal telescope. They are also used to detect objects that have had a high red-shift (shifting of wavelength towards the red end of the spectrum).

Note: Night vision is different from Thermal imaging.

Night vision is seeing objects at night using infrared devices, which is basically increasing the visibility in the dark without using a visible light source. These infrared devices increase the amount of available light in the night thereby increasing visibility.

Thermal imaging is a process by which thermal images are captured and the images are totally dependant on the amount of heat (infrared radiation) emitted by a body

Is there a glossary about which infrared (IR) colors which body parts reflect? - Biology

Everything is made up of electromagnetic energy vibrating at different frequencies that correspond to sound, light and color. We are drawn to the colors needed to create balance in our lives, the goal in all healing. Our consciousness and emotions align with the colors we wear, home design, and often our diet. Some people dream in color, others in black and white. ROYGBIV is an acronym for the sequence of hues commonly described as making up a rainbow.

Blue is a color, the perception of which is evoked by light having a spectrum dominated by energy with a wavelength of roughly 440-490 nm. It is considered one of the additive primary colors.

On the HSV Color Wheel, the complement of blue is yellow that is, a color corresponding to an equal mixture of red and green light. On a color wheel based on traditional color theory (RYB), the complementary color to blue is considered to be orange (based on the Munsell color wheel).

The English language commonly uses "blue" to refer to any color from navy blue to cyan. The word itself is derived from the Old French word bleu.

A Scots and Scottish English word for "blue-grey" is blae, from the Middle English bla ("dark blue," from the Old English blood). Ancient Greek lacked a word for color blue and Homer called the color of the sea "wine dark", except that the word kyanos (cyan) was used for dark blue enamel.

In the English language, blue may refer to the feeling of sadness. This is because blue was related to rain, or storms, and in Greek mythology, the god Zeus would make rain when he was sad (crying), and a storm when he was angry. Kyanos was a name used in Ancient Greek to refer to dark blue tile (in English it means blue-green or cyan). The phrase "feeling blue" is linked also to a custom among many old deepwater sailing ships. If the ship lost the captain or any of the officers during its voyage, she would fly blue flags and have a blue band painted along her entire hull when returning to home port.

Many languages do not have separate terms for blue and or green, instead using a cover term for both (when the issue is discussed in linguistics, this cover term is sometimes called grue in English). Blue is commonly used on internet browsers to color a link that has not been clicked when a link has been clicked it changes yellow or orange or purple.

Blue is the color of truth, serenity and harmony, by helping to soothe the mind. It is good for cooling, calming, reconstructing and protecting. good for fevers, calming the body and mind, raising frequency, etc.

Blue is the color of electricity. We experience in a program created by electromagnetic energy that had a beginning and is evolving out of physical consciousness.

Blue relates to the future in linear time as it is a faster moving frequency than we experience in the physical. Consciousness is moving into the blue. (Midnight) Blue takes us to 12:00, 12 around 1 creational geometry, 2012 Mayan Calendar Prophecy, Hopi Blue Kachina Prophecies, Isis/Sirius, and more.

Experts discover traces of rare artificial pigment on Egyptian mummy portraits and panel paintings Ancient Origins - August 29, 2015

Egyptian Blue is one of the first artificial pigments known to have been used by man. First created around 5,000 years ago by heating a mixture of a calcium compound, a copper-containing compound, silica sand and soda or potash to around 850-950 C, the precious pigment was reserved for the most exquisite of artworks. In Egyptian belief, blue was considered the color of the heavens, and hence the universe. It was also associated with water and the Nile. However, scientists have now found traces of the rare pigment behind drab-colored mummy portraits, leading to a new understanding of how this particular pigment was used by artists in the second century A.D.

Egyptian Blue Hides in These Mummy Portraits Epoch Times - August 29, 2015

Dusting off 15 Roman-era Egyptian mummy portraits - mostly untouched for 100 years - has revealed a 2,000-year-old surprise. Researchers discovered that the ancient artists used the pigment Egyptian blue as material for underdrawings and for modulating color -a finding never documented before. Because blue has to be manufactured, it typically is reserved for very prominent uses, not hidden under other colors. We see how these artists manipulated a small palette of pigments, including this unusual use of Egyptian blue, to create a much broader spectrum of hues.

Red is any of a number of similar colors evoked by light consisting predominantly of the longest wavelengths of light discernible by the human eye, in the wavelength range of roughly 625-740 nm. Longer wavelengths than this are called infrared, or below red and cannot be seen by the naked human eye. Red is used as one of the additive primary colors of light, complementary to cyan, in RGB color systems. Red is also one of the subtractive primary colors of RYB color space but not CMYK color space.

In human color psychology, red is associated with heat, energy and blood, and emotions that "stir the blood", including anger, passion, and love.

Red is any of a number of similar colors evoked by light consisting predominantly of the longest wavelengths of light discernible by the human eye, in the wavelength range of roughly 630-700 nm. Longer wavelengths than this are called infrared, or below red and cannot be seen by human eyes.

Red's wavelength has been an important factor in laser technologies as red lasers, used in early compact disc technologies, are being replaced by blue lasers, as red's longer wavelength causes the laser's recordings to take up more space on the disc than blue lasers. Red light is also used to preserve night vision in low-light or night-time situations, as the rod cells in the human eye aren't sensitive to red. Red is used as one of the additive primary colors of light, complementary to cyan, in RGB color systems. Red is also one of the subtractive primary colors of RYB color space but not CMYK color space.

One common use of red as an additive primary color is in the RGB color model. Because "red" is not by itself standardized, color mixtures based on red are not exact specifications of color either. In order to produce exact colors the color red needs to be defined in terms of an absolute color space such as sRGB. As used in computer monitors and television screens, red is very variable, but some systems may apply color correction (so that a standardized "red" is produced that is not in fact full intensity of only the red colorant).

A red filter used in black and white photography increases contrast in most scenes. For example, combined with a polarizer, it can turn the sky black. Films simulating the effects of infrared film (such as Ilford's SFX 200) do so by being much more sensitive to red than to other colors. Red illumination was (and sometimes still is) used as a "safelight" while working in a darkroom, as it does not expose most photographic paper and some films. Though many more modern darkrooms use an amber safelight, red illumination is closely associated with the darkroom in the public mind.

Etymology and Definitions

The word red comes from the Old English read. Further back, the word can be traced to the Proto-Germanic rauthaz and the Proto-Indo European root reudh-.

This is the only color word which has been traced to an Indo-European root.

In Sanskrit, the word rudra means red. In the English language, the word red is associated with the color of blood, certain flowers (i.e. roses), and ripe fruits (i.e. apples, cherries). Fire is also strongly connected, as is the sun and the sky at sunset.

Healthy people are often said to have a redness to their skin color (as opposed to be appearing pale). After the rise of socialism in the mid-19th century, red was to describe revolutionary movements. The word is also obviously associated with anything of the color occupying the lower end of the visible light spectrum, such as red hair or red soil.

Red Indians is a British term for Native Americans, American terms for this ethnic group include redskin, redhead and red man, though they are not the preferred terms.

In astronomy, stars of spectral type M (the stars with the coolest temperature) are classified as red stars.

Mars is called the Red Planet because of the reddish color imparted to its surface by the abundant iron oxide present there. Astronomical objects which are moving away from the observer exhibit a red shift.

Jupiter's surface displays a Great Red Spot, a football-shaped area south of the planet's equator. Astronomers believe the spot to be some kind of storm.

Oxygenated blood is red due to the presence of oxygenated hemoglobin.

Red light is the first to be absorbed by sea water, so that many fish and marine invertebrates that appear bright red are black in their native habitat.

When used about animal coloration red usually refers to a brownish, reddish-brown or ginger color. In this sense it is used to describe coat colors of reddish-brown cattle and dogs, and in the names of various animal species or breeds such as red fox, red squirrel, red deer, Robin Redbreast, Red Grouse, Red Knot, Redstart, Redwing, Red Setter, Red Devon cattle etc.

The usage for animal color appears similar to that for red ochre, red hair and Red Indian.

Red appears to be rarely used in names of animals which are a brighter blood-red or scarlet color (Carmine Bee-eater, Scarlet Tanager). When used for flowers, red often refers to purplish (red deadnettle, red clover, red helleborine) or pink (red campion, red valerian) colors.

Aggression, anger, blood, blushing, stop, Communism, courage, danger, guilt, energy, fire, hate, hell, honor, leadership, passion, socialism, sacrifice, sex, sin, violence, negativity, warning.

A biblical example is found in Isaiah: "Though your sins be as scarlet, they shall be white as snow." Also, The Scarlet Letter an 1850 American novel by Nathaniel Hawthorne, features a woman in a Puritan New England community who is punished for adultery with ostracism, her sin represented by a red letter 'A' sewn into her clothes. This all comes from a general Hebrew view inherited by Christianity which associates red with the blood of murder, as well as with guilt in general.

Another popular example of this is in the phrase "caught red-handed", meaning either caught in an act of crime or caught with the blood of murder still on one's hands. At one point, red was associated with prostitutes, or now, with brothels (red-light districts).

In Roman Catholicism, red represents wrath, one of the Seven Deadly Sins. In Christianity, Satan is usually depicted as colored red and/or wearing a red costume in both iconography and popular culture. Statistics have shown that red cars are more likely to be involved in accidents.

The color red is associated with lust, passion, love, and beauty as well. The association with love and beauty is possibly related to the use of red roses as a love symbol. Both the Greeks and the Hebrews considered red a symbol of love, as well as sacrifice. Psychological research has shown that men find women who are wearing red more attractive.

Red is also used as a symbol of courage and sacrifice, as in blood spilt in sacrifice or courage in the face of lethal danger. Examples of this are found in the flags of many nations including the United States, as well as in the novel The Red Badge of Courage, in which a soldier in the American Civil War discovers the meaning of courage.

Besides the association with guilt previously mentioned, in Christianity, red represents the color of Christian martyrs who suffered death for their faith. It is sometimes used for Holy Thursday and during Eastertide, and red green and white is the color scheme of Christmas. In Roman Catholic tradition it is used for all feast days of Christian martyrs as well as Palm Sunday in anticipation of the death of Jesus.

Along the same lines, red is associated in Roman mythology with the god of war, Mars. A Roman general receiving a triumph had his entire body painted red in honor of his achievement.The phrase "red-blooded" describes someone who is audacious, robust, or virile.

In English heraldry, red (called gules) denoted ardent affection or love, while crimson (blood-color) stood for boldness, enthusiasm, or impetuosity.

Red catches people's attention, and is often used either in a negative way to indicate danger and emergency, or in a positive way in advertising to gain more viewers, or in nature, as a ripe fruit announces its readiness with its red color. Several studies have indicated that red carries the strongest reaction of all the colors, with the level of reaction decreasing gradually with orange, yellow, and white, respectively. Because of this, scientists have repeatedly recommended red for warning signals, labels, and signs. Because of these recommendations, red has seen widespread use as a danger signal, in stop signs, to warn people of extreme heat or flammability, and even to signal warnings in sports such as soccer.

Red may represent fire and so may symbolize the presence of God.

In Christianity, red is the liturgical color for Pentecost. Also, in the Catholic Church red is the color of a martyr.

In Islam red is the color for sacrificement and courage. Many Islamic states have it as a sign of the courage of Muslims and the sacrifice of their lives for what is good.

In metaphysics red connects with the root chakra.

Alice Bailey developed a system called the Seven Rays, where she classified humans into seven different metaphysical psychological types, the "sixth ray" of "love-devotion" is represented by the color red. People who have this metaphysical psychological type are said to be "on the Red Ray".

Psychics who claim to be able to observe the aura with their third eye report that a red aura is associated with a love of sports and physical exercise.

In China, red is the symbol of fire and the south (both south in general and Southern China specifically). It carries a largely positive connotation, being associated with courage, loyalty, honor, success, fortune, fertility, happiness, passion, and summer. In Chinese cultural traditions, red is associated with weddings (where brides traditionally wear red dresses) and red paper is also frequently used to wrap gifts of money or other things. Special red packets called hong bao as in Mandarin or lai see as in Cantonese - are specifically used during the Chinese New Year to give monetary gifts. On the more negative end, obituaries are traditionally written in red ink, and to write someone's name in red signals either cutting them out of your life, or that they have died. Red is also associated with both the feminine yin and the masculine yang, depending on the source. When someone commits suicide, especially a female, and wants to haunt their loved one, they will dress in red from top to bottom before carrying out the act.

In Japan, red is a traditional color for a heroic figure.

In the Indian Sub-continent, red is the traditional color of bridal dresses, and is frequently represented in the media as a symbolic color for married women. The color is associated with sexuality in marriage relationships through its connection to heat and fertility. It is also the color of wealth, beauty, and the goddess Lakshmi.

In Central Africa, Ndembu warriors rub themselves with red during celebrations. Since their culture sees the color as a symbol of life and health, sick people are also painted with it. Like most Central African cultures, the Ndembu see red as ambivalent, better than black, but not as good as white.[39] In other parts of Africa, however, red is a color of mourning, representing death. Because of the connection red bears with death in many parts of Africa, the Red Cross has changed its colors to green and white in parts of the continent.

The Color Red In the News .

Red on Women Drives Men Wild Live Science - October 28, 2008

The color orange occurs between red and yellow in the visible spectrum at a wavelength of about 585 - 620 nm, and has a hue of 30 degrees in HSV color space. The complementary color of orange is azure, a slightly greenish blue. Orange pigments are largely in the ochre or cadmium families, and absorb mostly blue light.

The color is named after the orange fruit, introduced to Europe via the Sanskrit word naranja. Before this was introduced to the English-speaking world, the color was referred to (in Old English) as geoluhread, which translates into Modern English as yellow-red. The first recorded use of orange as a color name in English was in 1512, in the court of King Henry VIII.

In metaphysics orange connects with the spleen chakra.

Orange is the color of creativity, sexuality, joy, enthusiasm, and promotes a general sense of wellness.

Orange Crystals include Orange Amber, Carnelian, Citrine, Orange Jade, Orange Calcite, Fire Agate, Orange Quartz, Orange Rhodochrosite, Orange Garnet, more

Yellow is the color evoked by light that stimulates both the L and M (long and medium wavelength) cone cells of the retina about equally, but does not significantly stimulate the S (short-wavelength) cone cells that is, light with much red and green but not very much blue.

Light with a wavelength of 570-580 nm is yellow, as is light with a suitable mixture of somewhat longer and shorter wavelengths. Yellow's traditional RYB complementary color is purple, violet or indigo. Yellow's colorimetrically defined complementary color in both RGB and CMYK color spaces is blue.

The word yellow comes from the Old English geolu, which derived from the Proto-Germanic word gelwaz. The oldest known usage of this word in English is in the Old English poem Beowulf, in a description of a shield made of wood from a yew tree.

In the English language, yellow is used to describe objects having the color between green and orange in the visible light spectrum (gold, egg yolks, sunflowers, etc.). The color is associated with age and aging, both with people and objects (e.g. yellowed-paper). Ethnographically, the term yellow has also been used as a slang term for both oriental persons and light-skinned African-Americans. The term is associated at times with jealousy, as well as cowardliness. Lastly, it is associated with sensational journalistic practices, or yellow journalism, and resistance to militant trade unions.

In metaphysics orange connects with the solar plexus.

Yellow is the color of intellect and it is used for mental clarity. Linked to the sun and the lion, yellow is connected to the source of creation as its frequency emerges into white light and consciousness.

Green is a color, the perception of which is evoked by light having a spectrum dominated by energy with a wavelength of roughly 520-570-nm. In the subtractive color system, it is not a primary color, but is created out of a mixture of yellow and blue, or yellow and cyan it is considered one of the additive primary colors. On the HSV color wheel, the complement of green is magenta that is, a purple color corresponding to an equal mixture of red and blue light. On a color wheel based on traditional color theory (RYB), the complementary color to green is considered to be red.

The word green is closely related to the Old English verb growan, 'to grow'. It is used to describe plants or the ocean. Sometimes it can also describe someone who is inexperienced, jealous, or sick. In America, green is a slang term for money, among other things. Several colloquialisms have derived from these meanings, such as 'green around the gills', a phrase used to describe a person who looks ill.

Several minerals have a green color, including the emerald, which is colored green by its chromium content. Animals such as frogs, lizards, and other reptiles and amphibians, fish, insects, and birds, appear green because of a mixture of layers of blue and green coloring on their skin. By far the largest contributor to green in nature is chlorophyll, the chemical by which plants photosynthesize. Many creatures have adapted to their green environments by taking on a green hue themselves as camouflage.

Culturally, green has broad and sometimes contradictory meanings. In some cultures, green symbolizes hope and growth, while in others, it is associated with death, sickness, envy or the devil.

The most common associations, however, are found in its ties to nature. For example, Islam venerates the color, as it expects paradise to be full of lush greenery. Green is also associated with regeneration, fertility and rebirth for its connections to nature. Recent political groups have taken on the color as symbol of environmental protection and social justice, and consider themselves part of the Green movement, some naming themselves Green parties. This has led to similar campaigns in advertising, as companies have sold green, or environmentally friendly, products.

The word green comes from the Old English word grene, or, in its older form, groeni. This adjective is closely related to the Old English verb growan (to grow) and goes back into Western Germanic and Scandinavian languages.

The word designates the color on the visible light spectrum situated between blue and yellow. It is often used to describe foliage and the sea, and has become a symbol of environmentalism. It also is combined with other color names to increase specificity, as in blue-green, or with objects, as in emerald green. Green is also used to describe jealousy and envy, as well as anyone young, inexperienced, or gullible (probably by analogy to unripe, i.e. unready or immature, fruit).

Green is sometimes associated with nausea and sickness.

Lastly, green can communicate safety to proceed, as in traffic lights.

Overall, greens, along with blues and purples, are frequently described as cool colors, in contrast to red and yellow.

Some languages have no word separating green from blue.

The word green is found in several colloquial phrases derived from these meanings: in golf, the region of grass around the hole is trimmed short and referred to as the putting green, or simply, the green.

Someone who works well with plants is said to have a green thumb or green fingers, a physically-ill person is said to look green around the gills, and the word greenhorn refers to an inexperienced person.

A company is greenwashing if they advertise positive environmental practices to cover up environmental destruction.

Green with envy highlights another emotional association, which William Shakespeare had first described as the "green-eyed monster" in Othello and The Merchant of Venice.

In areas that use the U.S. Dollar as currency, green carries a connotation of money, wealth, and capitalism, because green is the color of United States banknotes, giving rise to the slang term greenback for cash.

The Libyan flag is completely green, in honor of Islam's veneration of the color.

Green is considered the traditional color of Islam, likewise because of its association with nature. This is for several reasons. First, Muhammad is reliably quoted in a hadith as saying that 'water, greenery, and a beautiful face' were three universally good things.

In the Qur'an, sura Al-Insan, believers in God in Paradise wear fine green silk.

Also, Al-Khidr (The Green One), is a Qur'anic figure who met and traveled with Moses. The flag of Hamas, as well as the flag of Iran, is green, symbolizing their Islamist ideology.

Roman Catholic and more traditional Protestant clergy wear green vestments at liturgical celebrations during Ordinary Time.

In the Eastern Catholic Church, green is the color of Pentecost.

Green is one of the Christmas colors as well, possibly dating back to pre-Christian times, when evergreens were worshipped for their ability to maintain their color through the winter season. Romans used green holly and evergreen as decorations for their winter solstice celebration called Saturnalia, which eventually evolved into a Christmas celebration.

One of the more notable uses of this meaning is found in The Wonderful Wizard of Oz. In this story is the Emerald City, where everyone wears tinted glasses which make everything look green. According to the populist interpretation of the story, the city's color is used by the author, L. Frank Baum, to illustrate the financial system of America in his day, as he lived in a time when America was debating the use of paper money versus gold.

Alice Bailey, in her system called the Seven Rays which classifies humans into seven different metaphysical psychological types, the "third ray" of "creative intelligence" is represented by the color green. People who have this metaphysical psychological type are said to be "on the Green Ray".

In Hinduism, Green is used to symbolically represent the fourth, heart chakra (Anahata).

Psychics who claim to be able to observe the aura with their third eye report that someone with a green aura is typically someone who is in an occupation related to health, such as a physician or nurse, as well as people who are lovers of nature and the outdoors.

Green frequency is linked to healing and alchemy.

Purple is a general term for the range of shades of color occurring between red and blue. In color theory, a 'purple' is defined as any non-spectral color between violet and red. The spectral color violet is not a purple.

In art, purple is the color on the color wheel between magenta and violet and its tints and shades. This color, electric purple, is shown below.

In human color psychology, purple is associated with royalty, regality, and nobility (stemming from its use in heraldry to denote gentry)

In metaphysics purple connects with the crown chakra.

In healing purple is good for emotional problems, rheumatism, epilepsy, reducing pain, deep tissue work, bones.

The Violet Flame is supposedly charged with the light of divine freedom. It is used to burn off karma from other lifetimes on all levels.

White is a tone, the perception which is evoked by light that stimulates all three types of color sensitive cone cells in the human eye in near equal amount and with high brightness compared to the surroundings.

Since the impression of white is obtained by three summations of light intensity across the visible spectrum, the number of combinations of light wavelengths that produce the sensation of white is practically infinite.

There are a number of different white light sources such as the midday Sun, incandescent lamps, fluorescent lamps and white LEDs. The impression of white light can also be created by mixing appropriate intensities of the primary colors of light - red, green and blue (RGB) - a process called additive mixing, as seen in many display technologies.

White light reflected off objects can be seen when no part of the light spectrum is reflected significantly more than others and the reflecting material has a degree of diffusion. This is seen when transparent fibers, particles, or droplets are in a transparent matrix of a substantially different refractive index. Examples include classic "white" substances such as sugar, foam, pure sand or snow, cotton, clouds, and milk.

Crystal boundaries and imperfections can also make otherwise transparent materials white, as in the milky quartz or the microcrystalline structure of a seashell. This is also true for artificial paints and pigments, where white results when finely divided transparent material of a high refractive index is suspended in a contrasting binder. Typically paints contain calcium carbonate and/or synthetic rutile with no other pigments if a white color is desired.

In painting, white can be crafted by reflecting ambient light from a white pigment, although the ambient light must be white light, or else the white pigment will appear the color of the light. White when mixed with black produces gray. To art students, the use of white can present particular problems, and there is at least one training course specializing in the use of white in art. In watercolor painting, white areas are the absence of paint on the paper. When mixing paints in order to get a lighter color, it's advisable to mix a small amount of color to white, rather than trying to add white to the color, as it will take considerably more paint to get the desired tint.

White light is the octave (frequency) above purple. It has always been seen as transcendence, pure, perfection, innocence, chastity, the triumphant of spirit over the flesh, purity.

In Alchemy white is the feminine principle or highest frequency of though turning into pure consciousness.

Wearing white links to the goddess in many civilizations.

Druid priests often wore white.

In Christian beliefs white is the highest color representing the purified soul, joy, virginity, integrity, light and a holy life. White is always worn in Christian religions at the sacraments of Baptism, First Communion, Confirmation, Marriage. In Catholicism it is symbolic of the saints not suffering martyrdom and virgin saints.

To the Buddhist tradition, white is self-mastery and redemption. It is representative of being lead from bondage - the highest spiritual transformation.

In Hinduism, white is symbolic of pure consciousness, upward movement, light, and manifestation.

Maori tradition holds white as meaning truce or surrendering.

In Mayan tradition it represented peace and health.

The color of a candle works well with the frequency you seek at a given point in time. This again follows the color spectrum and its meanings. For example if you want to gain knowledge, light a yellow candle. Some candles not only coordinate colors, but fragrances and shapes as well.

Using a lamp with a specific colored light bulb creates interesting frequencies that can allow you to see yourself in past lives, to heal, for spiritual work, and more. Fluorescent light bulbs work best in a dark room.

Color Breathing and Visualization

When meditating, envision colors entering your body with each breath. Select the color you are drawn to by frequency. Visualize it entering its color coordinated chakra as it enters and clears. Visualize yourself bathed in the colors you choose to resonate with.

Which areas of our brains represent the colors we see? Medical Express - May 28, 2020

Red, orange, yellow, green, blue, indigo and violet: The colors of the rainbow are well known to anyone who remembers "Roy G. Biv." However, scientific research has long shown that such colors are not inherent to the physical world, but rather a result of how our brains process light.

Earth's Oldest Color, Pink, Dates Back More Than 1 Billion Years Live Science - July 10, 2018
Is bright pink the new black? Well, not exactly, but it is the world's oldest-known color, according to new research. Researchers extracted the pigment from bacteria fossils preserved in rocks under the Sahara Desert in Mauritania, West Africa. Inside those teensy bacteria, the scientists found chlorophyll - a pigment used today by plants for photosynthesis - dating back to about 1.1 billion years ago. That's about 600 million years older than similar chlorophyll fossils found previously, scientists reported in the new study. Their findings hint that cyanobacteria, bacteria that survive on sunlight, appeared much earlier than algae, which have been traced to around 650 million years ago. And bacteria likely dominated Earth's ancient oceans for hundreds of millions of years, according to the study.

Superhuman 'Rainbow Vision' Common, But Untested Discovery - March 17, 2016
A fairly common genetic mutation in some women allow them to see more colors than the average person. But few who carry the mutation regularly demonstrate this nearly super-human rainbow vision. Results from new scientific experiments may explain why and the development of a new image-processing filter could help potential tetrachromats develop their unique talent.

Seeing the sunnier side of life: Scientists bring a whole new meaning to winter blues Science Daily - August 5, 2015
Scientists at the University of York have shed new light on how humans process color - revealing that we see things differently in winter compared with summer. The researchers examined how our color perception changes between seasons and in particular how we process the color known as unique yellow. Humans identify four unique hues - blue, green, yellow and red -- that do not appear to contain mixtures of other colors.

How the Brain Remembers Colors Live Science - June 2, 2015

When you bring home the wrong color of paint from the hardware store, it may not be your foggy memory at fault. A new study finds that while the human brain can distinguish between millions of colors, it has difficulty remembering specific shades. For example, most people can easily tell the difference between azure, navy and ultramarine, but when it comes to remembering these shades, people tend to label them all as blue, the study found. This tendency to lump colors together could explain why it's so hard to match the color of house paint based on memory alone, the researchers said. Many cultures have the same color words or categories.

Researchers explore how prior knowledge influences our visual senses PhysOrg - November 1, 2013

The perception and processing of color has fascinated neuroscientists for a long time, as our brain influences our perception of it to such a degree that colors could be called an illusion. One mystery was: What happens in the brain when we look at black-and-white photographs? Do our brains fill in the colors? Neuroscientists showed study participants black-and-white photos of bananas, broccoli, strawberries, and of other objects associated with a typical color (yellow, red and green in the examples above). While doing so, they recorded their subjects' brain activity using functional imaging. The true purpose of the study was unknown to the subjects, and to distract their attention they were shown slowly rotating objects and told to report the direction in which they were moving.

After recording brain responses to the black and white objects, the scientists presented real colors to their subjects, in the shape of yellow, green, red and blue rings. This allowed them to record the activity of the brain as it responded to different, real colors. It turned out that the mere sight of black-and-white photos automatically elicited brain activity patterns that specifically encoded colors. These activity patterns corresponded to those that were elicited when the observers viewed real color stimuli. These patterns encoded the typical color of the respective object seen, even though it was presented in black and white. The typical colors of the presented objects could therefore be determined from the brain's activity, even though they were shown without color.

Bach to the Blues, Our Emotions Match Music to Colors Science Daily - May 17, 2013

Whether we're listening to Bach or the blues, our brains are wired to make music-color connections depending on how the melodies make us feel. People in both the United States and Mexico linked the same pieces of classical orchestral music with the same colors. This suggests that humans share a common emotional palette -- when it comes to music and color -- that appears to be intuitive and can cross cultural barriers, UC Berkeley researchers said. The results were remarkably strong and consistent across individuals and cultures and clearly pointed to the powerful role that emotions play in how the human brain maps from hearing music to seeing colors.

Red-Green & Blue-Yellow: The Stunning Colors You Can't See Live Science - January 18, 2012

Try to imagine reddish green - not the dull brown you get when you mix the two pigments together, but rather a color that is somewhat like red and somewhat like green. Or, instead, try to picture yellowish blue - not green, but a hue similar to both yellow and blue. Is your mind drawing a blank? That's because, even though those colors exist, you've probably never seen them. Red-green and yellow-blue are the so-called "forbidden colors." Composed of pairs of hues whose light frequencies automatically cancel each other out in the human eye, they're supposed to be impossible to see simultaneously.

The limitation results from the way we perceive color in the first place. Cells in the retina called "opponent neurons" fire when stimulated by incoming red light, and this flurry of activity tells the brain we're looking at something red. Those same opponent neurons are inhibited by green light, and the absence of activity tells the brain we're seeing green. Similarly, yellow light excites another set of opponent neurons, but blue light damps them. While most colors induce a mixture of effects in both sets of neurons, which our brains can decode to identify the component parts, red light exactly cancels the effect of green light (and yellow exactly cancels blue), so we can never perceive those colors coming from the same place.

Brain study explores what makes colors and numbers collide PhysOrg - November 17, 2011
Someone with the condition known as grapheme-color synesthesia might experience the number 2 in turquoise or the letter S in magenta. Now, researchers reporting their findings online in the Cell Press journal Current Biology on November 17 have shown that those individuals also show heightened activity in a brain region responsible for vision.

Different Colors Describe Happiness vs. Depression Live Science - February 9, 2010
Are you in a gray mood today? How about a blue funk? Maybe you're seeing red, because you're green with jealousy. The colors we use to describe emotions may be more useful than you think, according to new research. The study found that people with depression or anxiety were more likely to associate their mood with the color gray, while happier people preferred yellow. The results, which are detailed today in the journal BMC Medical Research Methodology, could help doctors gauge the moods of children and other patients who have trouble communicating verbally.

Red vs. Blue: Why Necktie Colors Matter Live Science - February 7, 2009
In high-stakes politics and business, there are only two colors of ties: red and blue. Oh, sure, you might spot purple or yellow now and then, but those are clear statements of aloofness, be they calculated or careless. Few world leaders or CEOs want to be seen as aloof. But does it matter whether one wears red or blue? Yes, suggest several studies, including a new one out today in the journal Science. More on that in a moment.

Using color as a medicine BBC News - January 20, 2002
Sitting by the pool surrounded by bright reds, blues and oranges in a modern abstract design, you would be forgiven for thinking you were at a spa in a hotel rather than in the hydrotherapy room at a major London hospital. The colors in this room make you feel good. In fact, you may even want to take a dip.

Find a Specialist Find a Specialist

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

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Practical Solutions to Real Light Measurement Problems

Here's The Problem:
You must design optical diffuser reflectors for a custom design LED sources that optimize and diffuse emitted light for specific tasks. The metal reflectors you have tried do not provide a diffuse light output. The various white coatings and paints diffuse the light sufficiently but are too fragile in some applications. Plus some of the coatings were not reflective enough, causing too low a light level.

There are other synthetic white reflectance materials that would work. However, the manufacturers do not sell just the material they want to do the machining of the parts themselves.

  • A durable high reflectance white optical diffuser material available as raw stock in various shapes and sizes for in-house machining.
  • Fabrication of the parts in-house is necessary not only to save costs but to also allow the flexibility for trial and error design of multiple reflector solutions.

Here's The Solution:
ODM98 optical diffuser with high reflectance in various size unmachined plate, block, cylinder or film form.

Interested in discussing your light measurement application?
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