Fluorescence image-guided surgery

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Fluorescence image-guided surgery
Specialtyoncology (surgery)

Fluorescence guided surgery (FGS), also called fluorescence image-guided surgery, or in the specific case of tumor resection, fluorescence guided resection, is a

near infrared are used.[3]

Imaging devices

FGS is performed using imaging devices with the purpose of providing real time simultaneous information from color

reflectance images (bright field) and fluorescence emission. One or more light sources are used to excite and illuminate the sample. Light is collected using optical filters that match the emission spectrum of the fluorophore. Imaging lenses and digital cameras (CCD or CMOS) are used to produce the final image. Live video processing can also be performed to enhance contrast during fluorescence detection and improve signal-to-background ratio. In recent years a number of commercial companies have emerged to offer devices specializing in fluorescence in the NIR wavelengths, with the goal of capitalizing upon the growth in off label use of indocyanine green (ICG). However commercial systems with multiple fluorescence channels also exist commercially, for use with fluorescein and protoporphyrin IX (PpIX).[citation needed
]

Excitation sources

Fluorescence excitation is accomplished using various kind of light sources.

laser diodes, particularly when high power over a short wavelength range (typically 5-10 nm) is needed.[6] In this case the system has to account for the limits of exposure to laser radiation.[7]

Detection techniques

Live images from the fluorescent dye and the surgical field are obtained using a combination of filters, lenses and cameras. During

open surgery, hand held devices are usually preferred for their ease of use and mobility.[8] A stand or arm can be used to maintain the system on top of the operating field, particularly when the weight and complexity of the device is high (e.g. when multiple cameras are used). The main disadvantage of such devices is that operating theater lights can interfere with the fluorescence emission channel, with a consequent decrease of signal-to-background ratio. This issue is usually solved by dimming or switching off the theater lights during fluorescence detection.[9]

FGS can also be performed using minimally invasive devices such as

fiber optics
in endoscopes and laparoscopes, particularly in the near infrared. Moreover, the ability of collecting light is much reduced compared to standard imaging lenses used for open surgery devices. FGS devices can also be implemented for
robotic surgery (for example in the da Vinci Surgical System).[11]

Clinical applications

The major limitation in FGS is the availability of clinically approved fluorescent dyes which have a novel biological indication. Indocyanine green (ICG) has been widely used as a non-specific agent to detect sentinel lymph nodes during surgery.[12] ICG has the main advantage of absorbing and emitting light in the near infrared,[3] allowing detection of nodes under several centimeters of tissue. Methylene blue can also be used for the same purpose, with an excitation peak in the red portion of the spectrum.[13] First clinical applications using tumor-specific agents that detect deposits of ovarian cancer during surgery have been carried out.[14]

History

The first uses of FGS dates back to the 1940s when fluorescein was first used in humans to enhance the imaging of brain tumors, cysts, edema and blood flow in vivo.[15] In modern times the use has fallen off, until a multicenter trial in Germany concluded that FGS to help guide glioma resection based upon fluorescence from PpIX provided significant short-term benefit.[16]

See also

References

  1. S2CID 237149829
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  2. PMID 18711192
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  3. ^ a b Prahl S. "Optical Absorption of Indocyanine Green (ICG)". Omic.org. OMLC.
  4. PMID 22577366
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  5. PMID 19723473
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  6. ISSN 1818-2259
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  7. ^ "Archived copy" (PDF). Archived from the original (PDF) on 2007-09-27. Retrieved 2009-12-28.{{cite web}}: CS1 maint: archived copy as title (link)
  8. ^ "Physics Update". physicstoday. American Institute of Physics. October 31, 2011. Archived from the original on October 27, 2012. Retrieved September 18, 2018.
  9. PMID 22752379
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  10. PMID 22876351
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  11. PMID 21996262
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  12. PMID 22577366
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  13. PMID 20117811
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  14. ^ Fang J (September 19, 2011). "Glowing cancer cells help surgeons remove tumors from ovaries". ZDNet. CBS Interactive.
  15. PMID 18872412
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  16. PMID 16648043
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