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New MRI model estimates portal pressure as well as HVPG

A combined model of non-invasive quantitative MRI measures of liver spine-echo echo planar imaging longitudinal relaxation time and splenic artery velocity can provide an estimation of portal pressure that is significantly correlated with hepatic venous pressure gradient measurement, according to recent findings published in the Journal of Hepatology.

“In the present study we have demonstrated that a combination of non-invasive quantitative magnetic resonance measures of liver [spine-echo echo planar imaging (SE-EPI)] T₁ relaxation time and splenic artery velocity can provide a non-invasive estimation of portal pressure,” Naaventhan Palaniyappan, MBBS, at the University of Nottingham, and colleagues wrote. “The combined model of structural and hemodynamic magnetic resonance measures identified in this study provides the best predictor to accurately reflect the portal pressures through its full range from normal to clinically significant portal hypertension.”

Hepatic venous pressure gradient (HVPG) is the only technique for evaluating changes in portal pressure that is currently validated, the researchers wrote.

Palaniyappan and colleagues evaluated the use of non-contrast quantitative MRI as a replacement measure for portal pressure in 30 patients undergoing HVPG measurement. The researchers assessed MR parameters of longitudinal relaxation time (T₁) perfusion of the liver and spleen and blood flow in the portal, splanchnic and collateral circulation. They estimated the liver stiffness measurement and the enhanced liver fibrosis score. Afterward, they evaluated the correlation of all non-invasive parameters with HVPG.

The mean HVPG of the patients was 9.8 mmHg (95% CI, 1-22) and 14 patients had clinically significant portal hypertension, which is defined as at least 10 mmHg. Liver T₁ relaxation time, splenic artery and superior mesenteric artery velocity were significantly correlated with HVPG. In multiple linear regression, liver T₁ and splenic artery velocity remained significantly associated with HVPG (P < .001). This correlation remained for patients with clinically significant portal hypertension (P < .001). A validation cohort of 10 patients showed this model to be a good predictor of HVPG. Further, liver stiffness management and enhanced liver fibrosis scores correlated significantly with HVPG in the entire population but not in patients with clinically significant portal hypertension.

The researchers concluded that this proposed model, if confirmed in a validation cohort, could replace HVPG.

“If these results are confirmed by external validation, this non-invasive model … could be used as a surrogate measure of HVPG in clinical trials of portal hypertension as well as monitoring treatment in clinical practice,” the researchers wrote. – by Will Offit

Disclosure: The researchers report funding from the National Institute of Health Research at the University of Nottingham.