Quantification of indocyanine green near-infrared fluorescence bowel perfusion assessment in colorectal surgery.

BACKGROUND: Indocyanine green near-infrared fluorescence bowel perfusion assessment has shown its potential benefit in preventing anastomotic leakage. However, the surgeon's subjective visual interpretation of the fluorescence signal limits the validity and reproducibility of the technique. Therefore, this study aimed to identify objective quantified bowel perfusion patterns in patients undergoing colorectal surgery using a standardized imaging protocol. METHOD: A standardized fluorescence video was recorded. Postoperatively, the fluorescence videos were quantified by drawing contiguous region of interests (ROIs) on the bowel. For each ROI, a time-intensity curve was plotted from which perfusion parameters (n = 10) were derived and analyzed. Furthermore, the inter-observer agreement of the surgeon's subjective interpretation of the fluorescence signal was assessed. RESULTS: Twenty patients who underwent colorectal surgery were included in the study. Based on the quantified time-intensity curves, three different perfusion patterns were identified. Similar for both the ileum and colon, perfusion pattern 1 had a steep inflow that reached its peak fluorescence intensity rapidly, followed by a steep outflow. Perfusion pattern 2 had a relatively flat outflow slope immediately followed by its plateau phase. Perfusion pattern 3 only reached its peak fluorescence intensity after 3 min with a slow inflow gradient preceding it. The inter-observer agreement was poor-moderate (Intraclass Correlation Coefficient (ICC): 0.378, 95% CI 0.210-0.579). CONCLUSION: This study showed that quantification of bowel perfusion is a feasible method to differentiate between different perfusion patterns. In addition, the poor-moderate inter-observer agreement of the subjective interpretation of the fluorescence signal between surgeons emphasizes the need for objective quantification.

Quantitative assessment of nipple perfusion with near-infrared fluorescence imaging.

Preserving the nipple-areolar complex with a nipple-sparing mastectomy improves cosmesis compared with skin-sparing mastectomy. However, complications such as necrosis of the nipple-areolar complex significantly affect cosmetic outcome. Many factors influence nipple-areolar perfusion, and no consensus currently exists on optimal incisional choice. This study evaluates 2 nipple-sparing mastectomy incision models using near-infrared fluorescence to assess perfusion quantitatively. The periareolar and radial incisions were compared with 2 control models in Yorkshire pigs (N = 6). Methylene blue and indocyanine green were injected intravenously, and near-infrared fluorescence images were recorded at 3 time points: before surgery, immediately after (0 hour), and 3 days postoperatively. Contrast-to-background ratio was used to assess perfusion. At 72 hours, radial incisions showed a statistically significantly higher perfusion compared with periareolar incisions (P < 0.05). Based on our findings, radial incisions for nipple-sparing mastectomy may be preferable due to higher perfusion; however, clinical trials are necessary for further assessment.

Simultaneous assessment of luminal integrity and vascular perfusion of the gastrointestinal tract using dual-channel near-infrared fluorescence.

Anastomotic complications such as stenosis and leakage in the gastrointestinal (GI) tract can cause high patient morbidity and mortality. To identify the potential preconditions of these complications intraoperatively, we explored the use of two 700 nm near-infrared (NIR) fluorophores administered intraluminally: (1) chlorella, an over-the-counter herbal supplement containing high concentrations of chlorophyll, and (2) methylene blue (MB). In parallel, we administered the 800 nm NIR fluorophore indocyanine green (ICG) intravenously to assess vascular function. Dual-channel, real-time intraoperative imaging and quantitation of the contrast to background ratio (CBR) were performed under normal conditions or after anastomosis or leakage of the stomach and intestines in 35 kg Yorkshire pigs using the Fluorescence-Assisted Resection and Exploration (FLARE) imaging system. Luminal integrity could be assessed with relatively high sensitivity with either chlorella or MB, although chlorella provided significantly higher CBR. ICG angiography provided assessment of blood perfusion of normal, ischemic, and anastomotic areas of the GI tract. Used simultaneously, 700 nm (chlorella or MB) and 800 nm (ICG) NIR fluorescence permitted independent assessment of luminal integrity and vascular perfusion of the GI tract intraoperatively and in real time. This technology has the potential to identify critical complications, such as anastomotic leakage, intraoperatively, when correction is still possible.