Clinical application of fluorescence guided surgery

The term fluorescence guided surgery (FGS) describes a medical technology based on real-time imaging intended to help and guide the surgeon during his operating practice.
In last years many innovations in surgical technique and minimally invasive technologies with laparoscopic, endoscopic and robotic techniques, has greatly improved surgical practice. Nevertheless, despite these constant advances, surgery still relies primarily on the surgeon's vision and on white-light reflectance. The emerging field of fluorescent surgical imaging promises to be a powerful enhancement to improve surgical guidance.
Among all cromophores and fluorophores that could work as probes in medical imaging techniques, Near-infrared (NIR) fluorescence imaging with Indocyanine green (ICG) is emerging as major contributions to intraoperative surgical decisions and many different applications have already been described in literature. ICG is a dye used in medicine since the mid-1950s for a variety of diagnostic applications in cardiology, ophthalmology and to test the hepatic clearance; however, its fluorescent properties have only recently been applied to new minimally invasive surgical instrumentations. ICG has some peculiar features that promote its widespread use: it is virtually harmless, due to lowest rate of adverse effects reported and to very high toxic dose for human body, and it is not expensive. In addition FGS appears to have a great potential to become a standard in everyday clinical practice due to the multiple different possible applications and the ease of employ. Our group started working on this technology since few years ago, cooperating with one of surgical imaging leading company on the market in developping new applications and tehcnical improvements.
As ICG, once injected, is excreted through the bile, it simply allows to outline the biliary tree anatomy by visualization under NIR light. This application find its ultimate use during laparoscopic cholecystectomy (LC). LC is one of the most common procedure in general surgery worldwide (750.000 cases are performed every year in the United States); the most temible surgical complication of LC is biliary duct injuries (BDI), that could lead to severe consequences in terms of morbidity and mortality of patients. Several studies have already reported that the the primary cause of BDI is misinterpretation of biliary anatomy (71%-97% of all cases), in some cases influenced by lack of tactile feedback and anatomic variations. FGS with ICG can be used effectively in LC to visualize the biliary system and avoid injuries; to date in literature several authors published case reports or small data series on this methodic, nevertheless larger randomized controlled studies are needed to confirm and validate the potential role of this technology as gold standard for LC. Another extremely interesting field of employment of ICG fluorescent guided surgery is intraoperative angiography; ICG injected into the bloodstream and excited by NIR light can give information about study vascular anatomy and parenchimal perfusion in various clinical situations. Our group, at the beginning of our experience with ICG FGS, tested several possible “angiographic” applications (clarify vascular anatomy for dissection in delicate procedures or solid organ perfusion for transplants) but we decided to focus our studies on the assessment of bowel microperfusion before anastomosis creation.
Anastomotic leak (AL) is a frequent and serious complication in gastrointestinal resective surgery and adequate bowel perfusion has been stressed as one of the key elements for suture healing. Currently, there is no widespread method to assess and quantify the perfusion of gastrointestinal anastomoses intra- operatively, besides the subjective evaluation by the surgeon. Real time intraoperative ICG fluorescent angiography (FA) is a feasible technique and a promising tool for everyday surgical practice. Nevertheless randomized controlled trials are needed to standardize technique and determine if ICG-FA might have positive impact on the AL rate in gastrointestinal anastomoses.