Hydrogen-1 MR Spectroscopy for Measurement and Diagnosis of Hepatic Steatosis

Abstract

OBJECTIVE. Hydrogen-1 MR spectroscopy (¹H-MRS) is gaining acceptance as a noninvasive technique for assessment of hepatic steatosis, and the findings have been found to correlate closely with histopathologic grade. The aims of this study were to validate ¹H-MRS performed with a 3-T MRI system for quantifying hepatic steatosis and to determine threshold values of ¹H-MRS proton density fat fraction corresponding to standard histopathologic grade in patients undergoing diagnostic liver biopsy. SUBJECTS AND METHODS. We conducted a prospective cross-sectional liver MRS study with 52 subjects undergoing diagnostic liver biopsy. The diagnostic accuracy of ¹H-MRS was evaluated with receiver operating characteristic curves. RESULTS. The diagnostic accuracy of ¹H-MRS for hepatic steatosis was high with an area under the receiver operating characteristic curve of 0.94 (95% CI, 0.88–1.0). Results were similar for three ¹H-MRS measurements obtained at different locations in the liver, for two independent pathologists, and whether fibrosis was present or absent. One third of participants had elevated transaminase concentrations of unknown cause, and ¹H-MRS estimates of steatosis had perfect agreement with histopathologic grade in this group. Calculated ¹H-MRS proton density fat fraction thresholds for histologic grades were less than 17% for grade 0 or trace steatosis, 17–38.6% for grade 1, and greater than 38.6% for grade 2 or higher. CONCLUSION. Hydrogen-1 MR spectroscopy is an effective, noninvasive technique that can be used to diagnose and quantify hepatic steatosis. Hydrogen-1 MR spectroscopy thresholds corresponded with histopathologic grades and may be useful in the workup of patients with elevated transaminase concentrations.