Computer-assisted analysis of ICG fluorescence signal for evaluation of small intestinal anastomotic perfusion.
A randomised, blinded, experimental trial
Indocyanine green fluorescence imaging (ICG-FI) may be used to visualize intestinal perfusion prior to anastomosis. Methods for quantification of the fluorescence signal are required to ensure a more standardised evaluation of the fluorescence.
The aim of the present study was to evaluate a method for quantification of relative perfusion by ICG-FI and to investigate the correlation between the perfusion level and the anastomotic strength.
This blinded, randomised, experimental trial included twenty pigs. Each pig received three small intestinal anastomoses with 30%, 60%, or 100% perfusion respectively (Fig. 1). The perfusion levels were determined relative to healthy intestine. Ligated ischemic segments were created in small intestinal loops and the perfusion level of each anastomotic level was determined using a software-based analysis of the fluorescence signal, based on the slope of the fluorescence curve (Fig. 2). On postoperative day five the anastomoses were subjected to tensile strength test and histopathological assessment.
No anastomotic leakage was found. The tensile strength of the 30% perfusion group (PG30) was 9.09 N, which was significantly lower than the 60% (PG60) and the 100% (PG100) group, with mean values of 11.5 N and 12.9 N respectively (Fig. 3). The histopathological assessment showed no significant differences between perfusion groups.
Reducing blood supply to 30% in small intestinal anastomoses, as evaluated by quantified ICG-FI, can be correlated to a lower tensile strength compared to 60% and 100% perfusion.