Portal hypertension correlates with splenic stiffness as measured with MR elastography

Purpose: To investigate the correlation between MR elastography (MRE) assessed spleen stiffness and direct portal vein pressure gradient (D-HVPG) measurements in a large animal model of portal hypertension. Materials and Methods: Cholestatic liver disease was established in adult canines by common bile duct ligation. A spin echo based echo planar imaging (EPI) MRE sequence was used to acquire three-dimensional/three axis (3D/3-axis) abdominal MRE data at baseline, 4 weeks, and 8 weeks. Liver biopsies, blood samples, and D-HVPG measurements were obtained simultaneously. Results: Animals developed portal hypertension (D-HVPG: 11.0 ± 5.1 mmHg) with only F1 fibrosis after 4 weeks. F3 fibrosis was confirmed after 8 weeks despite no further rise in portal hypertension (D-HVPG: 11.3 ± 3.2 mmHg). Mean stiffnesses of the spleen increased over two-fold from baseline (1.72 ± 0.33 kPa) to 4 weeks (3.54 ± 0.31 kPa), and stabilized at 8 weeks (3.38 ± 0.06 kPa) in a pattern consistent with changes in portal pressure. A positive correlation was observed between spleen stiffness and D-HVPG (r² = 0.86; P < 0.01). Conclusion: These findings indicate a temporal relationship between portal hypertension and the development of liver fibrosis in a large animal model of cholestatic liver disease. The observed direct correlation between spleen stiffness and D-HVPG suggest a noninvasive MRE approach to diagnose and screen for portal hypertension.