Chemical shift magnetic resonance imaging is helpful in detecting hepatic steatosis but not fibrosis in patients with nonalcoholic fatty liver disease (NAFLD)

Background & Aim: Imaging modalities have a role in the diagnosis of patients with nonalcoholic fatty liver disease. Aim of the present study was to evaluate the role of chemical shift magnetic resonance imaging in assessing hepatic steatosis and fibrosis hi patients with nonalcoholic fatty liver disease. Methods: Chemical shift magnetic resonance imaging was done in 10 biopsy proven patients (7 females, mean age, 41 +/- 9.2 years) with nonalcoholic fatty liver disease. Objective measurements of signal intensity (SI) were done and a ratio was calculated (SI out-of-phase liver/SI out-of-phase kidney)/(SI in-phase liver/SI in-phase kidney). A lower ratio indicated a higher signal drop and hence higher fat content. The ratio was correlated with hepatic steatosis on histology (< 33% and > 33%). Patients were classified as having histological NASH or no NASH and MRI was assessed in diagnosing hepatic fibrosis as seen on liver histology. Results : Six patients had > 33% hepatic steatosis on histology. Five patients (50%) had evidence of histological NASH. MRI was not helpful in differentiating patients with and without histological NASH. One patient amongst NASH patients did not have fibrosis, one had stage 1, 2 had stage 2 and one had stage 4 fibrosis. SI ratio ranged between 0.35-0.69 in 6 patients with steatosis > 33% and was in the range of 0.69-1.20 in four patients with steatosis < 33% on histology. Fibrotic changes seen in 4 patients on biopsy were not detected on MRI. Conclusion: Chemical shift MRI provides objective data on fat infiltration in patients with NAFLD without giving information about hepatic fibrosis.