Optimizing quantitative fluorescence angiography for visceral perfusion assessment

Background Compromised tissue perfusion is a significant risk factor for anastomotic leakage after intestinal resection, leading to prolonged hospitalization, risk of recurrence after oncologic resection, and reduced survival. Thus, a tool reducing the risk of leakage is highly warranted. Quantitative indocyanine green angiography (Q-ICG) is a new method that provides surgeons with an objective evaluation of tissue perfusion. In this systematic review, we aimed to determine the optimal methodology for performing Q-ICG. Method A comprehensive search of the literature was performed following the PRISMA guidelines. The following databases were searched: PubMed, Embase, Scopus, and Cochrane. We included all clinical studies that performed Q-ICG to assess visceral perfusion during gastrointestinal surgery. Bias assessment was performed with the Newcastle Ottawa Scale. Results A total of 1216 studies were screened, and finally, 13 studies were included. The studies found thatintensityparameters (maximum intensity and relative maximum intensity) could not identify patients with anastomotic leakage. In contrast, theinflowparameters (time-to-peak, slope,andt(1/2)max) were significantly associated with anastomotic leakage. Only two studies performed intraoperative Q-ICG while the rest performed Q-ICG retrospectively based on video recordings. Studies were heterogeneous in design, Q-ICG parameters, and patient populations. No randomized studies were found, and the level of evidence was generally found to be low to moderate. Conclusion The results, while heterogenous, all seem to point in the same direction. Fluorescenceintensityparameters are unstable and do not reflect clinical endpoints. Instead,inflowparameters are resilient in a clinical setting and superior at reflecting clinical endpoints.