Magnetic Resonance Elastography as a Predictor of Insufficient Liver Enhancement on Gadoxetic Acid–Enhanced Hepatocyte-Phase Magnetic Resonance Imaging in Patients With Type C Hepatitis and Child-Pugh Class A Disease

Abstract

The aim of this study was to examine liver stiffness value measured by magnetic resonance elastography (MRE) and laboratory test results to find the best method for predicting insufficient liver enhancement on gadoxetic acid-enhanced hepatocyte-phase images. The institutional ethics committee approved this retrospective study with waiver of informed consent. In total, 118 patients with Child-Pugh class A disease and type C hepatitis underwent MRE and gadoxetic acid-enhanced magnetic resonance imaging. During MRE examination, a pneumatic passive driver was used to obtain liver stiffness in kPa. Liver enhancement was assessed using liver-to-spleen contrast ratio (LSR), calculated using signal intensities of the liver and spleen on hepatocyte-phase magnetic resonance images obtained 20 minutes after contrast administration of gadoxetic acid. Insufficient liver enhancement was defined as an LSR lower than 1.5. The following laboratory test results were used as possible predictors of insufficient liver enhancement as well as liver stiffness measured by MRE: albumin, total bilirubin, aspartate aminotransferase, percentage prothrombin time, and platelet count. Correlation coefficients were calculated between LSR and these variables. Logistic analysis was performed to determine independent predictors of insufficient liver enhancement. All possible predictors investigated were significantly correlated with LSR. Logistic regression analysis revealed that MRE was the only variable to predict insufficient liver enhancement, with an odds ratio (95% confidence interval) of 2.03 (1.22-3.85) (P = 0.0138). A cutoff value of greater than 6.4 kPa yielded 95% specificity for predicting insufficient liver enhancement. Gadoxetic acid is not recommended in patients with liver stiffness greater than 6.4 kPa (consistent with severe fibrosis) because of insufficient liver enhancement on hepatocyte-phase images.