Breath-hold perfusion and permeability mapping of hepatic malignancies using magnetic resonance imaging and a first-pass leakage profile model.

Abstract

We have applied a novel pharmacokinetic model of the distribution of contrast media to dynamic contrast-enhanced MRI data from patients with hepatic neoplasms. The model uses data collected during the passage of a bolus of contrast medium and allows breath-hold image acquisition. The aims of the study were to investigate the feasibility of permeability mapping using the first pass technique and breath-hold acquisitions, and to examine the reproducibility of the technique and the effect of the liver's dual vascular supply on the assumptions of the model. Imaging was performed in 14 patients with hepatic neoplasms. Dynamic data clearly demonstrated differences in the timing and shape of the contrast medium concentration-time course curve in the systemic arterial and portal venous systems. Mapping of the arrival time (T(0)) of contrast medium allowed identification of tissue supplied by the hepatic arteries and portal vein. Hepatic tumours all showed typical hepatic arterial enhancement. Repeated measurements of endothelial permeability surface area product (k(fp)) and relative blood volume (rBV), performed in five patients, showed excellent reproducibility with variance ratios (V(r)) of 0.134 and 0.113, respectively. Measurement of enhancing tumour volume was also highly reproducible (V(r) = 0.096) and this was further improved by the use of T(0) maps to identify pixels supplied by the hepatic artery (V(r) = 0.026). Estimates of k(fp) and rBV in normal hepatic tissue supplied by the portal vein were highly inaccurate and these pixels were identified by use of the T(0) parameter and excluded from the analysis. In conclusion, dynamic MRI contrast enhancement combined with a pharmacokinetic model of the distribution of contrast media in the first pass allows us to produce highly reproducible parametric maps of k(fp) and rBV from hepatic tumours that are supplied by the hepatic arterial system using breath-hold acquisitions.