Non-invasive assessment of portal hypertension using quantitative magnetic resonance imaging

Abstract

Background & Aims: Hepatic venous pressure gradient (HVPG) measurement is currently the only validated technique to accurately evaluate changes in portal pressure. In this study, we evaluate the use of non-contrast quantitative magnetic resonance imaging (MRI) as a surrogate measure of portal pressure. Methods: Thirty patients undergoing HVPG measurement were prospectively recruited. MR parameters of longitudinal relaxation time (T 1), perfusion of the liver and spleen (by arterial spin labelling), and blood flow in the portal, splanchnic and collateral circulation (by phase contrast MRI) were assessed. We estimated the liver stiffness measurement (LSM) and enhanced liver fibrosis (ELF) score. The correlation of all non-invasive parameters with HVPG was evaluated. Results: The mean (range) HVPG of the patients was 9.8 (1-22) mmHg, and 14 patients (48%) had clinically significant portal hypertension (CSPH, HVPG P10 mmHg). Liver T 1 relaxation time, splenic artery and superior mesenteric artery velocity correlated significantly with HVPG. Using multiple linear regression, liver T 1 and splenic artery velocity remained as the two parameters in the multivariate model significantly associated with HVPG (R = 0.90, p <0.001). This correlation was maintained in patients with CSPH (R = 0.85, p <0.001). A validation cohort (n = 10) showed this linear model provided a good prediction of HVPG. LSM and ELF score correlated significantly with HVPG in the whole population but the correlation was absent in CSPH. Conclusions: MR parameters related to both hepatic architecture and splanchnic haemodynamics correlate significantly with HVPG. This proposed model, confirmed in a validation cohort, could replace the invasive HVPG measurement.