Feasibility of Novel Software-Based Perfusion Indicators for the Ileal J-Pouch—On the Path towards Objective and Quantifiable Intraoperative Perfusion Assessment with Indocyanine Green Near-Infrared Fluorescence

Abstract

Background: In restorative proctocolectomy with ileal J-pouch, perfusion assessment is vital to prevent complications such as anastomotic leak (AL). Indocyanine green near-infrared fluorescence (ICG-NIRF) is gaining popularity, while its interpretation and relevance remain subjective. This study aimed to evaluate a standardized ICG-NIRF imaging protocol combined with a novel, software-based assessment to detect areas of impaired perfusion and a possible correlation with AL of the pouch. Methods: In this prospective study, patients undergoing ileal J-pouch for ulcerative colitis at an inflammatory bowel disease (IBD) referral center were included. Intraoperatively, strictly standardized ICG-NIRF visualization was performed and video-recorded. Postoperatively, a specific software was utilized to determine the change in fluorescence intensity per second (i/s) for systematic regions of interest, generating perfusion-time curves and a pixel-to-pixel map. These were analysed in detail and correlated with clinical outcome (primary end point: AL within 30 days; clearly defined and screened for by pouchoscopy). Results: Four out of 18 included patients developed AL of the ileal pouch-anal anastomosis (IPAA). In the AL group, the perfusion curves on the area adjacent to the IPAA (pouch apex) displayed considerably lower ingress/inflow (median = 1.7; range = 8.5; interquartile-range = 3.8 i/s) and egress/outflow (median = −0.1; range = 0.7; interquartile-range = 0.5 i/s) values than in the non-AL group (ingress: median = 4.3; range = 10.3; interquartile-range = 4.0 i/s); egress: median = (−1.1); range = 3.9; interquartile range = 1. i/s). This was confirmed by further novel parameters of pouch perfusion (maximum ingress; maximum egress) and pixel-to-pixel analysis. Conclusions: This study presents the feasibility of a novel methodology to precisely assess pouch perfusion with ICG-NIRF, identifying comparable, quantifiable, and objective parameters to potentially detect perfusion-associated complications in surgery in real-time.

Optimizing Indocyanine Green Dosage for Near-Infrared Fluorescence Perfusion Assessment in Bowel Anastomosis: A Prospective, Systematic Dose-Ranging Study

“…Despite the statistical significance, the signal intensity at lower dosages was still sufficient for perfusion assessment, suggesting that these differences may not have substantial clinical implications. The focus of ICG-NIRF imaging should be on the optimal dosage and imaging environment for software-based quantitative, objective perfusion assessment methods rather than the visual signal intensity, as previously reported [19][20][21][22].…”

“…Moreover, a widespread heterogeneity can be observed in the literature regarding the timepoint and localization of ICG application [1,23]. Separate studies need to be conducted for each setting, focusing on potential differences in dosage and application of ICG in different surgical contexts, as already partly conducted by our group [20][21][22]24]. Additionally, our methodology could be combined with pulse spectrophotometry of ICG and blood samples to evaluate ICG clearance and predict a curve of metabolism and clearance versus time for ICG imaging.…”

Indocyanine Green Fluorescence Guided Surgery in Colorectal Surgery

“…How can one assess the ICG signal with certainty and objectively? Lobbes et al [ 29 ] sought to address this issue using novel software to assess the ICG signal for pouch perfusion in order to make this assessment quantifiable and comparable. Although the available literature supports the use of ICG in IPAA surgery, the level of evidence is still low.…”

“…Anastomotic Perfusion [ 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 26 , 27 , 28 , 29 ]…”