In vivo imaging of hepatic hemodynamics and light scattering property during ischemia-reperfusion in rats based on spectrocolorimetry

Abstract

A red-green-blue camera-based imaging method is proposed for estimating spatial maps of concentrations of oxyhemoglobin (<i>C</i>_HbO), deoxyhemoglobin (<i>C</i>_HbR), total hemoglobin (<i>C</i>_HbT), tissue oxygen saturation (<i>StO</i>₂), and scattering power (<i>b</i>) in liver tissue. Hemodynamic responses to hepatic ischemia-reperfusion of <i>in vivo</i> rat liver tissues induced by portal triad occlusion were evaluated. Upon portal triad occlusion, this method yielded images of decreased <i>C</i>_HbO, <i>C</i>_HbT, <i>StO</i>₂, and <i>b</i>, and increased <i>C</i>_HbR followed by a progressive increase in <i>C</i>_HbO and <i>StO</i>₂ during reperfusion. Time courses of the changes in <i>C</i>_HbO, <i>C</i>_HbR, <i>C</i>_HbT, and <i>StO</i>₂ over different regions of interest (ROI_s) revealed that ischemia results in an abrupt significant (<i>P</i><0.05) reduction in <i>C</i>_HbO, <i>C</i>_HbT, and <i>StO</i>₂ with a simultaneous increase in <i>C</i>_HbR compared to the baseline level, indicative of the hemodynamic responses during hepatic ischemia-reperfusion. Upon reperfusion, there was a gradual increase in <i>C</i>_HbO and <i>StO</i>₂, and decrease in <i>C</i>_HbR. The change in average scattering power <i>b</i> implies the presence of morphological alterations in the cellular and subcellular structures induced by ischemia or anoxia. This study shows the potential of monitoring spatiotemporal changes in hemodynamic parameters and morphological changes in studies of hepatic pathophysiology.