127 Quantitative analysis of intestinal perfusion with ICG and MB with low perfusion (ROI 3), a clearly non-steep ingress and lower maximum fluorescence intensity is demonstrated compared to watershed and normal perfusion ROIs. An example of both MB and ICG time-intensity curves is displayed in Figure 2. Figure 2. Time-intensity curve examples (Pig 3). ROI 1 = red (well-perfused), ROI2 = green (watershed), RO3 = blue (ischemic), ROI4 = yellow (watershed), ROI 5 = cyan (well-perfused), with corresponding NIRF images at 12 seconds. (A) MB mode (T = 10 min). (B) ICG mode (T = 60 min), red and cyanin line partly overlap. Fluorescence quantification analysis: ingress correlation to lactate levels First, all images of the ischemic loop during MB administration were analyzed (at T = 10 min). Ingress (i/s) values were calculated in all ROIs (Figure 3A). ROIs 1 and 5 had a faster development of brightness as compared to ROIs 2, 3, and 4. It is also objectively proven with the fluorescence quantification analysis of the ingress in which ROI 3 had the lowest ingress. Compared to local lactate levels, the opposite patterns were seen; ROI 3 had lower levels of lactate compared to watershed and well-perfused areas (Figure 3B). A Spearman’s correlation test showed a significant negative correlation between the ingress levels in the ischemic bowel loop and the corresponding local lactate levels (r = -0.7709, 95% CI: -0.9073 to -0.4878; p = <0.001) for MB fluorescence quantification analysis (Figure 3C). 6
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