A novel real-time assessment of intestinal perfusion with dual imaging using ICG fluorescence and capillaroscopy in colorectal surgery

PURPOSE: Anastomotic leakage (AL) is a major complication after colorectal surgery. Indocyanine green fluorescence imaging (ICG-FI) enables real-time assessment of intestinal perfusion, but remains subjective. This study quantitatively evaluated intestinal perfusion by combining ICG-FI with video capillaroscopy (VC). METHODS: Thirty-two patients undergoing colorectal surgery were enrolled. ICG was administered intravenously before anastomosis. Fluorescence time was defined as the interval from injection to initial fluorescence at the anastomotic site. Microvascular blood-flow velocity was measured intraoperatively using VC in fluorescent and non-fluorescent regions. RESULTS: AL occurred in 4 of 32 patients (12.5%). The AL group had significantly longer fluorescence time than the non-AL group (32.0 [25.3-34.3] vs. 20.0 [17.3-25.0] s, p = 0.014) and tended to have lower microvascular flow velocity in ICG-fluorescent regions (90.8 [49.0-249.8] vs. 231.7 [164.6-327.3] µm/s, p = 0.064). ROC analysis showed discriminative performance for fluorescence time (AUC 0.88, preliminary cutoff 32 s) and flow velocity (AUC 0.79, preliminary cutoff 101.6 μm/s). Fluorescence time and flow velocity were negatively correlated (r = - 0.41, p = 0.0195). CONCLUSIONS: Delayed fluorescence appearance on ICG-FI was associated with reduced VC-derived microvascular flow velocity. To our knowledge, this is the first study to integrate ICG-FI and VC intraoperatively for quantitative assessment of intestinal perfusion. Combined ICG-FI and VC assessment may provide physiological support for interpreting delayed fluorescence as a potential marker of microcirculatory impairment. Further validation is required to determine its clinical utility.