Orthogonal polarization spectral imaging as a tool for the assessment of hepatic microcirculations - A validation study

Background Quantitative analysis of liver microcirculation using intravital fluorescence microscopy in animals has increased our knowledge about ische mia-reperfusion injury, However, because of the size of the instrumentation and the necessity of fluochromes for contrast enhancement, human liver mic rocirculation cannot be observed, Orthogonal Polarization Spectral (OPS) im aging is a recently introduced technique that can be used to visualize the microcirculation without the need for fluorescent dyes. It is a small, hand -held device and could potentially be used to study the microcirculation of the human liver in a clinical setting. However, before implementation into clinical use its ability to quantitatively measure microcirculatory parame ters must be validated. Methods. The livers of Spraque-Dawley rats (n=9) were exteriorized, and ima ges were obtained using OPS imaging and intravital fluorescence microscopy of the identical microvascular regions before and after the induction of a 20-min warm lobar ischemia, Images were videotaped for later computer-assis ted off-line analysis. Results, OPS imaging can be used to accurately quantify the sinusoidal perf usion rate, vessel diameter, and venular red blood cell velocity. Correlati on parameters were significant and Bland-Altman analyses showed good agreem ent for data obtained from the two methods at baseline as well as during re perfusion, Conclusion. OPS imaging can be used to quantitatively measure microcirculat ory parameters in the rat liver under both physiological and pathophysiolog ical conditions. Thus, OPS imaging has the potential to be used to make qua ntitative measurements of the microcirculation in the human liver.