Quantification of hepatic steatosis: A comparison of computed tomography and magnetic resonance indices in candidates for living liver donation

摘要

Rationale and Objectives: To evaluate, in a group of candidates for liver donation, the role of unenhanced computed tomography (CT) and magnetic resonance (MR) as noninvasive means to measure hepatic steatosis (HS). Materials and Methods: Sixty-one consecutive candidates underwent CT and MR evaluation for liver donation within 3weeks of liver biopsy. On CT, three methods of HS quantification were evaluated: the measurement of hepatic attenuation (CT L), the ratio of hepatic attenuation to splenic attenuation (CT L/S), and the difference between the hepatic and splenic attenuation (CT L-S). On MR, HS was reported in terms of fat signal fraction (FSF) using in-phase/opposed-phase and faton-fat- saturated images, with and without normalization with the spleen (T1W IP/OP FSF, T1W IP/OP FSF spleen and T2W±FS FSF, TW2±FS FSF spleen). The accuracy of each imaging index in the diagnosis of HS, according to various thresholds, was assessed using receiver operating characteristic analysis. Results: On biopsy, 35 donors showed no significant HS (<5%); the remaining 26 showed HS ranging from 5% to 40%. With all CT and MR indices, there was a trend toward increasing diagnostic accuracy as the threshold levels of HS increased. When comparing all the indices, TW2±FS FSF(spl) showed higher accuracy at threshold levels of 5% and 10% of steatosis but without reaching statistical significance. Conclusions: In candidates for living donation, MR and CT indices are similar in estimating liver-fat content; however, MR with T2W±FS FSF(spl) sequences shows higher accuracy when low threshold levels of steatosis (≤5% and ≤10% HS) are selected.