126 Chapter 6 applied to all time-intensity curves. The ingress was the parameter used for the quantitative analysis of bowel perfusion assessment. The ingress quantifies the inflow in terms of increase in fluorescence intensity per second in the ROI (increase in a.u. per second: i/s). The ingress was calculated over a timeframe of 20 seconds after the end of the baseline. Numerical variables were presented as medians with interquartile range (IQR). A Spearman’s rho was calculated to correlate local lactates with the fluorescence parameter. A p < 0.05 was considered significant. All statistical analyses were performed with the GraphPad Prism (GraphPad software for Apple, version 8.0.0, San Diego, California, United States). RESULTS A total of 4 pigs were included in this experiment (Table 1). Systemic lactate levels confirmed that there was no systemic ischemia during the experiment. No intraoperative dye-related complications occurred. Table 1. Animal characteristics Pig 1 Pig 2 Pig 3 Pig 4 Weight (kg) 42.00 37.50 36.00 36.00 MB dose (mg/kg) 0.50 0.50 0.25 0.25 ICG dose (mg/kg) 0.20 0.20 0.20 0.20 Systemic lactate (mg/dL) T10 / T60 19 / 23 15 / 23 18 / 21 12 / 14 Lactate ROI 1 T10 / T60 21 /19 15 / 8 19 / 17 12 / 12 Lactate ROI 2 T10 / T60 28 / 57 40 / 41 16 / 16 59 / 53 Lactate ROI 3 T10 / T60 102 / 73 36 / 68 50 / 84 43 / 69 Lactate ROI 4 T10 / T60 34 / 91 42 / 46 15 / 8 43 / 51 Lactate ROI 5 T10 / T60 24 / 22 17 / 26 15 / 17 12 / 26 T = time in minutes. Bowel perfusion quantification Time-intensity curves In all included pigs, a clear macroscopic NIRF visualization of perfusion was achieved. For the well-perfused ROIs (1 and 5), the majority of curves displayed a steep ingress. In the time-intensity curves in the second ROI, marked as a watershed region, an inflow pattern comparable to ROI 4, also marked as a watershed region, was most often seen. For the ROIs
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