Fluorescence image-guided surgery

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Fluorescence image-guided surgery
Specialty oncology (surgery)

Fluorescence guided surgery (FGS), also called fluorescence image-guided surgery, or in the specific case of tumor resection, fluorescence guided resection, is a medical imaging technique used to detect fluorescently labelled structures during surgery. [1] Similarly to standard image-guided surgery, FGS has the purpose of guiding the surgical procedure and providing the surgeon of real time visualization of the operating field. When compared to other medical imaging modalities, FGS is cheaper and superior in terms of resolution and number of molecules detectable. [2] As a drawback, penetration depth is usually very poor (100 μm) in the visible wavelengths, but it can reach up to 1–2 cm when excitation wavelengths in the near infrared are used. [3]

Contents

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. [4] Halogen lamps have the advantage of delivering high power for a relatively low cost. Using different band-pass filters, the same source can be used to produce several excitation channels from the UV to the near infrared. Light-emitting diodes (LEDs) have become very popular for low cost broad band illumination and narrow band excitation in FGS. [5] Because of their characteristic light emission spectrum, a narrow range of wavelengths that matches the absorption spectrum of a given fluorophore can be selected without using a filter, further reducing the complexity of the optical system. Both halogen lamps and LEDs are suitable for white light illumination of the sample. Excitation can also be performed using 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 laparoscopes or endoscopes. In this case, a system of filters, lenses and cameras is attached to the end of the probe. [10] Unlike open surgery, the background from external light sources is reduced. Nevertheless, the excitation power density at the sample is limited by the low light transmission of the 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

Related Research Articles

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Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, than the absorbed radiation. A perceptible example of fluorescence occurs when the absorbed radiation is in the ultraviolet region of the electromagnetic spectrum, while the emitted light is in the visible region; this gives the fluorescent substance a distinct color that can only be seen when the substance has been exposed to UV light. Fluorescent materials cease to glow nearly immediately when the radiation source stops, unlike phosphorescent materials, which continue to emit light for some time after.

<span class="mw-page-title-main">Microscopy</span> Viewing of objects which are too small to be seen with the naked eye

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<span class="mw-page-title-main">Fluorescence spectroscopy</span> Type of electromagnetic spectroscopy

Fluorescence spectroscopy is a type of electromagnetic spectroscopy that analyzes fluorescence from a sample. It involves using a beam of light, usually ultraviolet light, that excites the electrons in molecules of certain compounds and causes them to emit light; typically, but not necessarily, visible light. A complementary technique is absorption spectroscopy. In the special case of single molecule fluorescence spectroscopy, intensity fluctuations from the emitted light are measured from either single fluorophores, or pairs of fluorophores.

<span class="mw-page-title-main">Fluorophore</span> Agents that emit light after excitation by light

A fluorophore is a fluorescent chemical compound that can re-emit light upon light excitation. Fluorophores typically contain several combined aromatic groups, or planar or cyclic molecules with several π bonds.

Laser-induced fluorescence (LIF) or laser-stimulated fluorescence (LSF) is a spectroscopic method in which an atom or molecule is excited to a higher energy level by the absorption of laser light followed by spontaneous emission of light. It was first reported by Zare and coworkers in 1968.

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<span class="mw-page-title-main">Indocyanine green</span> Chemical compound

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References

  1. ↑ Stewart, Hazel L.; Birch, David J. S. (2021). "Fluorescence Guided Surgery". Methods and Applications in Fluorescence. 9 (4): 042002. Bibcode:2021MApFl...9d2002S. doi: 10.1088/2050-6120/ac1dbb . ISSN   2050-6120. PMID   34399409. S2CID   237149829.
  2. ↑ Frangioni JV (August 2008). "New technologies for human cancer imaging". J. Clin. Oncol. 26 (24): 4012–21. doi:10.1200/JCO.2007.14.3065. PMC   2654310 . PMID   18711192.
  3. 1 2 Prahl S. "Optical Absorption of Indocyanine Green (ICG)". Omic.org. OMLC.
  4. ↑ Alander JT, Kaartinen I, Laakso A, Pätilä T, Spillmann T, Tuchin VV, Venermo M, Välisuo P (2012). "A review of indocyanine green fluorescent imaging in surgery". Int J Biomed Imaging. 2012: 940585. doi: 10.1155/2012/940585 . PMC   3346977 . PMID   22577366.
  5. ↑ Gioux, S; Kianzad, V; Ciocan, R; Gupta, S; Oketokoun, R; Frangioni, JV (May–Jun 2009). "High-power, computer-controlled, light-emitting diode-based light sources for fluorescence imaging and image-guided surgery". Molecular Imaging. 8 (3): 156–65. doi:10.2310/7290.2009.00009. PMC   2766513 . PMID   19723473.
  6. ↑ Gioux, Sylvain; Coutard, Jean-Guillaume; Josserand, Veronique; Righini, Christian; Dinten, Jean-Marc; Coll, Jean-Luc (2012). "Pushing the limits of fluorescence image-guided surgery". SPIE Newsroom. doi:10.1117/2.1201212.004621. ISSN   1818-2259.
  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. ↑ van der Vorst JR, Schaafsma BE, Verbeek FP, Hutteman M, Mieog JS, Lowik CW, Liefers GJ, Frangioni JV, van de Velde CJ, Vahrmeijer AL (December 2012). "Randomized comparison of near-infrared fluorescence imaging using indocyanine green and 99(m) technetium with or without patent blue for the sentinel lymph node procedure in breast cancer patients". Ann. Surg. Oncol. 19 (13): 4104–11. doi:10.1245/s10434-012-2466-4. PMC   3465510 . PMID   22752379.
  10. ↑ Gray DC, Kim EM, Cotero VE, Bajaj A, Staudinger VP, Hehir CA, Yazdanfar S (August 2012). "Dual-mode laparoscopic fluorescence image-guided surgery using a single camera". Biomed Opt Express. 3 (8): 1880–90. doi:10.1364/BOE.3.001880. PMC   3409706 . PMID   22876351.
  11. ↑ Rossi EC, Ivanova A, Boggess JF (January 2012). "Robotically assisted fluorescence-guided lymph node mapping with ICG for gynecologic malignancies: a feasibility study". Gynecol. Oncol. 124 (1): 78–82. doi:10.1016/j.ygyno.2011.09.025. PMID   21996262.
  12. ↑ Alander, Jarmo T.; Kaartinen, Ilkka; Laakso, Aki; Pätilä, Tommi; Spillmann, Thomas; Tuchin, Valery V.; Venermo, Maarit; Välisuo, Petri (1 January 2012). "A Review of Indocyanine Green Fluorescent Imaging in Surgery". International Journal of Biomedical Imaging. 2012: 940585. doi: 10.1155/2012/940585 . PMC   3346977 . PMID   22577366.
  13. ↑ Matsui, Aya; Tanaka, Eiichi; Choi, Hak Soo; Kianzad, Vida; Gioux, Sylvain; Lomnes, Stephen J.; Frangioni, John V. (2010). "Real-time, near-infrared, fluorescence-guided identification of the ureters using methylene blue". Surgery. 148 (1): 78–86. doi:10.1016/j.surg.2009.12.003. PMC   2886170 . PMID   20117811.
  14. ↑ Fang J (September 19, 2011). "Glowing cancer cells help surgeons remove tumors from ovaries". ZDNet. CBS Interactive.
  15. ↑ Moore, George; Peyton, William T.; French, Lyle A.; Walkter, Walter W. (1948). "The Clinical Use of Fluorescein in Neurosurgery: The localization of brain tumors". Journal of Neurosurgery. 5 (4): 392–398. doi:10.3171/jns.1948.5.4.0392. PMID   18872412.
  16. ↑ Stummer, W; pichlmeier U; Meinel T; Wiestler OD; Zanella F; Reulen HJ (2006). "Fluorescence-guided surgery with 5-aminolevulinic acid for resection of malignant glioma: a randomised controlled multicentre phase III trial". Lancet Oncology. 7 (5): 392–401. doi:10.1016/s1470-2045(06)70665-9. PMID   16648043.
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