Early Detection of Nonalcoholic Steatohepatitis in Patients with Nonalcoholic Fatty Liver Disease by Using MR Elastography

To investigate the diagnostic accuracy (area under the receiver operating characteristic curve [AUROC]) of magnetic resonance (MR) elastography for the early detection of nonalcoholic steatohepatitis (NASH) among patients with nonalcoholic fatty liver disease (NAFLD). An institutional review board-approved and HIPAA-compliant retrospective study was conducted in 58 NAFLD patients. Informed consent was waived by the review board. Hepatic stiffness, relative fat fraction, inflammation grade, and fibrosis stage were assessed from MR elastography, in-phase and out-of-phase gradient-echo imaging, and liver biopsy histopathologic review, respectively. Pairwise t testing, receiver operating characteristic analysis, and partial correlation analysis were performed. The mean hepatic stiffness for patients with simple steatosis (2.51 kPa) was less (P = .028) than that for patients with inflammation but no fibrosis (3.24 kPa). The mean hepatic stiffness for patients with inflammation but no fibrosis was less (P = .030) than that for patients with hepatic fibrosis (4.16 kPa). Liver stiffness had high accuracy (AUROC = 0.93) for discriminating patients with NASH from those with simple steatosis, with a sensitivity of 94% and a specificity 73% by using a threshold of 2.74 kPa. In patients with NAFLD, hepatic stiffness measurements with MR elastography can help identify individuals with steatohepatitis, even before the onset of fibrosis; NAFLD patients with inflammation but no fibrosis have greater liver stiffness than those with simple steatosis and lower mean stiffness than those with fibrosis.