Intrahepatic triglyceride measurement and estimation of viability in rat fatty livers by near-infrared spectroscopy.

Abstract

This study investigated the features of fatty livers using near-infrared (NIR) spectroscopy and validated the usefulness of NIR spectroscopy for the measurement of intrahepatic triglyceride (TG) contents and evaluation of viability in fatty livers. In vitro, we examined specific spectra for each purified TG fraction by NIR. In vivo, the differences between the spectra obtained from normal and fatty livers before warm ischemia and the differences between the spectra obtained from each rat liver before and after warm ischemia were subjected to multicomponent analysis. In vitro experiments revealed a specific peak at 925 nm in major TG fractions, and NIR spectroscopy precisely detected changes in TG volume. In vivo experiments revealed that NIR spectroscopy detected TG content changes in rat fatty livers induced by a choline-deficient diet following the addition of purified TG spectrum for NIR spectroscopic analysis in least square curve fitting. The TG level in the fatty livers measured by NIR spectroscopy significantly correlated with the morphometric measurement of lipid content in the livers. NIR spectroscopy also revealed decreased levels of total hemoglobin (Hb) and oxidized Hb and maintenance of homeostasis in cytochrome redox states in fatty livers under normal condition. However, NIR spectroscopy showed irreversible deterioration of hepatic microcirculation, Hb oxygenation and homeostasis of the cytochrome redox states in fatty livers after 60-min warm ischemia reperfusion. These studies demonstrated that NIR spectroscopy can quantitatively measure the intrahepatic TG content in addition to simultaneously evaluating microcirculation and Hb oxygenation.