A quantitative method for estimating hepatic blood flow using a dual-input single-compartment model

The purpose of this study was to investigate the accuracy of a quantitative method for estimating arterial hepatic blood flow and portal hepatic blood flow separately using a dual-input single-compartment model compared with the maximum slope method using computer simulations and clinical data. In computer simulations, the rate constants for the transfer of contrast agent (CA) from the hepatic artery to the liver (K_1a), from the portal vein to the liver (K_1p) and from the liver to the blood (k₂) were estimated from simulated time-density curves with various transit times of CA from the aorta to the liver (τ_a) and from the portal vein to the liver (τ_p) using the linear leastsquares (LLSQ) method. In clinical studies, dynamic CT data were acquired from 27 patients, and parametric maps of K_1a, K_1p and K₂ were generated by applying the LLSQ method pixel by pixel. In simulation studies, τ_a and τ_p were found to have a large and a small effect on the estimates of K_1a and K_1p, respectively. In clinical studies, the K_1a and K_1p values estimated with the maximum slope method were underestimated by 60 ± 29% and 37 ± 12%, respectively, compared with those estimated by the LLSQ method. In conclusion, our results suggest that correction of τ_a is necessary for accurately estimating K_1a and K_1p. Our method is therefore promising forthe evaluation of hepatic blood flow in various liver diseases because it allows us to evaluate arterial hepatic blood flow and portal hepatic blood flow separately and visually.