Assessment of Portal Hypertension With Multiparametric MRI

Overview

The purpose of this study is to determine whether new multiparametric magnetic resonance imaging (MRI) methods (including diffusion-weighted MRI, dynamic contrast-enhanced MRI, MR elastography and phase-contrast imaging) can be useful in assessing liver damage and degree of portal hypertension (a complication of advanced liver fibrosis and cirrhosis) secondary to chronic liver disease, compared to ultrasound measurement of liver stiffness \[acoustic radiation force impulse (ARFI) ultrasound\] and routine blood tests. MRI uses magnetic fields to look at soft tissues in the body. This study will ultimately help to determine whether these methods will be useful in identifying liver disease and their complications that cannot be well-understood using current liver MRI techniques.

Liver cirrhosis has been historically classified as a single histopathologic entity, as it is considered to be the latest fibrosis stage; however it is well known that cirrhosis encompasses different degrees of clinical severity. Advanced liver fibrosis and cirrhosis are commonly associated with portal hypertension, which is due to increased hemodynamic resistance of the liver leading to an increase in portal venous pressure. Portal hypertension leads to the development of esophageal varices associated with a high risk of bleeding, ascites and renal dysfunction. The definite diagnosis of portal hypertension is based on the measurement hepatic venous pressure gradient (HVPG), which is an indirect measure of portal pressure. This technique is invasive and not widely available. Portal hypertension may also be associated with a decrease in portal venous flow/velocity due to a higher parenchymal resistance to flow, and an increase in hepatic arterial flow secondary to an arterial buffer response that can be measured with phase-contrast magnetic resonance imaging (MRI). According to the researcher's recent data, the increased vascular pressure observed in portal hypertension affects liver and spleen stiffness as well as other viscoelastic properties measured with advanced 3D MR elastography, which may potentially be used as biomarkers of portal hypertension. In this proposal, the researchers would like to validate noninvasive imaging biomarkers based on a short multiparametric MRI protocol for the quantification of changes in viscoelastic properties and flow metrics in the liver and spleen in relation to portal hypertension. This protocol could potentially be integrated in routine clinical MRI exams, and could significantly reduce the cost of care by decreasing the need for HVPG measurement, upper gastrointestinal endoscopies, and could provide a novel risk stratification scoring system of liver disease and portal hypertension based on MRI. This will be a highly significant progression in patients with liver disease.