Autoimmune hepatitis: CT and MR imaging features with histopathological correlation.

BACKGROUND: To describe the CT and MRI features of autoimmune hepatitis (AIH) and correlate them with histological grade and stage. Observed changes associated with treatment are also described. METHODS: A retrospective analysis of the initial CT scans (n = 22) and MRI exams (n = 12) of 27 patients with pathologically-proven AIH was conducted. Multiple objective and subjective imaging features were evaluated. Correlation of imaging features with histological inflammatory grade and fibrotic stage was performed using the Fisher exact test and Spearman's rank correlation coefficient. In eight patients serial CT and MR imaging during treatment was used to describe the changes associated with treatment. RESULTS: The presence of ascites, expanded gallbladder fossa, spleen size, and enlarged preportal space had significant positive correlations with fibrotic stage. No significant positive correlations existed between imaging features and portal or lobular inflammatory grade. Seven patients (25.9%) were normal. The most common abnormal finding was surface nodularity: CT (n = 11 [50%]) and MRI (n = 8 [66.7%]). There was a wide variability in imaging appearances of patients who had serial scans on treatment. CONCLUSIONS: There is a wide spectrum of CT and MR imaging features in patients with AIH. Several MRI features demonstrate a significant positive correlation with fibrotic stage.