Assessment of Hepatic Steatosis in Patients Undergoing Liver Resection: Comparison of US, CT, T1-weighted Dual-Echo MR Imaging, and Point-resolved 1H MR Spectroscopy

Purpose: To compare the diagnostic performance of ultrasonography (US), computed tomography (CT), T1-weighted dual-echo magnetic resonance (MR) imaging, and point-resolved proton (hydrogen 1[H-1]) MR spectroscopy in the assessment of hepatic steatosis in patients undergoing liver resection. Materials and Methods: This prospective study was approved by the institutional review board, and patients gave written informed consent. US, CT, T1-weighted MR imaging, and H-1 MR spectroscopy were performed preoperatively in 46 patients. Imaging results were correlated (Spearman correlation coefficient) with histopathologic analysis of results of intraoperative liver biopsies. To assess differences between groups, one-way analysis of variance was used. Sensitivity and specificity were calculated for each imaging modality by using receiver operating characteristic curve analysis, with a histopathologic cut-off value of 5% macrovesicular steatosis. Differences in sensitivity and specificity were assessed by means of McNemar analysis. Results: At histopathologic examination, 23 patients had no (0%-5%) macrovesicular steatosis, 11 had mild (5%-33%), nine had moderate (33%-66%), and three had severe (>66%). MR imaging and H-1 MR spectroscopic measurements of hepatic fat had stronger correlation with histopathologic steatosis assessment (r = 0.85, P < .001 and r = 0.86, P < .001, respectively) than did US (r = 0.66, P < .001) and CT (r = -0.55, P < .001). Only T1-weighted MR imaging and H-1 MR spectroscopy showed differences across steatosis grades: none versus mild (P = .001 for both), mild versus moderate (P < .001 for both), and moderate versus severe (P = .04 and .01, respectively). Sensitivity of US, CT, T1-weighted MR imaging, and H-1 MR spectroscopy was 65% (13 of 20), 74% (17 of 23), 90% (19 of 21), and 91% (21 of 23), respectively, and specificity was 77% (17 of 23), 70% (14 of 20), 91% (20 of 22), and 87% (20 of 23), respectively. Conclusion: In contrast to US and CT, T1-weighted MR imaging and H-1 MR spectroscopy strongly correlate with histopathologic steatosis assessment and are able to demonstrate differences across steatosis grades. T1-weighted dual-echo MR imaging and H-1 MR spectroscopy had the best diagnostic accuracy in depicting hepatic steatosis. (C) RSNA, 2010