Clinical evaluation of kinetic model for the quantification of liver function with Tc-99m PMT and dynamic scintigraphy

The purpose of this study was to quantify the uptake and excretion of Tc-99m-N-pyridoxyl-5-methyltryptophan (PMT) by hepatocytes using a tracer kinetic modeling approach, and to clarify the pathophysiological changes of diffuse parenchymal liver disease. Fifty-two patients with liver disease and seven normal subjects were studied. Studied were performed using an intravenous bolus injection of 185 MBq of PMT. our compartment model consisted of three compartments. These parameters were calculated using the non-linear least-square method. The fitting curves agreed well with the measured ones. K1 correlated with blood tests of liver function better than parameters from the two-compartment model such as ku. K1 correlated especially closely with K-ICG (r=0.898). K1 reflected hepatic blood flow, and the decrease of K1 was associated with hepatic dysfunction. Although K3 correlated poorly with serum bilirubin (r=-0.447), it correlated well with MTT (deconvolutional analysis)(r=-0.833). K3 reflected excretory function, and did not decrease until liver function was moderately damaged. By using three-compartment analysis, we were better able to explain the pathophysiological status of the liver. Our model is more useful for the assessment of liver function than the simple model. (author)