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 (T₁), 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 ⩾10mmHg). Liver T₁ relaxation time, splenic artery and superior mesenteric artery velocity correlated significantly with HVPG. Using multiple linear regression, liver T₁ 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.

Lay summary: In patients with cirrhosis, the development and progression of portal hypertension is related to worse outcomes. However, the standard technique of assessing portal pressure is invasive and not widely used in clinical practice. Here, we have studied the use of non-invasive MRI in evaluating portal pressure. The MRI measures of liver architecture and blood flow in the splenic artery correlated well with portal pressure. Therefore, this non-invasive method can potentially be used to assess portal pressure in clinical trials and monitoring treatment in practice.

Keywords: Hepatic venous pressure gradient; Longitudinal T(1) relaxation time; Magnetic resonance imaging; Portal hypertension.

Graphical abstract

Fig. 1

Correlation between HVPG and serum markers of liver fibrosis. (A) Enhanced Liver Fibrosis (ELF) score, (B) hyaluronic acid (HA), (C) aminoterminal peptide of procollagen III (P3NP) and (D) tissue inhibitor of matrix metalloproteinase 1 (TIMP-1) concentrations.

Fig. 2

Correlation of HVPG with imaging markers of liver fibrosis. (A) liver stiffness measurement (LSM), (B) liver SE-EPI T₁ relaxation time (ms) and (C) the full-width-half-maximum (FWHM) of liver SE-EPI T₁ Gaussian distribution (ms).

Fig. 3

Example of T₁ relaxation maps. Top row shows example image quality of the coronal-oblique imaging slices for base equilibrium M₀ data acquired from a patient with HVPG of 3 mmHg. Subsequent rows show example coronal-oblique bFFE T₁∗ maps showing the liver and spleen, together with HVPG (mmHg) and mode of the liver T₁∗ value (ms) across a range of HVPG from 3–22 mmHg, with columns showing each of the five slices collected for the T₁∗ map.

Fig. 4

Correlation of HVPG with splanchnic and collateral flow. (A) superior mesenteric artery (SMA) velocity, (B) splenic artery (SA) velocity and (C) azygous vein (AZV) flow.

Fig. 5

Predictive MRI model for HVPG. Bland-Altman plot showing the difference between measured and predicted HVPG against the measured HVPG using (A) liver SE-EPI T₁ relaxation time alone, and (B) predictive MR model of liver SE-EPI T₁ relaxation time and splenic artery velocity. Data shown for original (blue diamonds) and validation cohort (red squares), with mean difference (solid line) and ±1.96 standard deviations (broken line) shown.