Parameter Comparison Between Fast-Water-Exchange-Limit-Constrained Standard and Water-Exchange-Modified Dual-Input Tracer Kinetic Models for DCE-MRI in Advanced Hepatocellular Carcinoma

Dynamic contrast-enhanced MRI (DCE-MRI) data have often been analyzed using classic standard tracer kinetic models that assume a fast-exchange limit (FXL) of water. Recently, it has been demonstrated that deviations from the FXL model occurs when contrast agent arrives at the target tissue. However, no systematic analysis has been reported for the liver tumor with dual blood supply. In this study, we compared kinetic parameter estimates from DCE-MRI in advanced hepatocellular carcinoma that have the same physiological meaning between five different FXL standard dual-input tracer kinetic models and their corresponding water-exchange-modified (WX) versions. Kinetic parameters were estimated by fitting data to analytic solutions of five different FXL models and their WX versions based on a full two-site-exchange model for transcytolemmal water exchange or a full three-site-two-exchange model for transendothelial and transcytolemmal water exchange. Results suggest that parameter values differ substantially between the FXL standard and WX tracer kinetic models, indicating that DCE-MRI data are water-exchange-sensitive.