Role of Diffusion-Weighted Magnetic Resonance Imaging in the Diagnosis and Grading of Hepatic Steatosis in Patients With Non-alcoholic Fatty Liver Disease: Comparison With Ultrasonography and Magnetic Resonance Spectroscopy

Nonalcoholic fatty liver disease (NAFLD) is becoming the most common cause of cirrhosis. Although magnetic resonance spectroscopy (MRS) is considered the gold standard, it has a few limitations. The role of diffusion-weighted imaging (DWI), which is a simpler sequence, in the diagnosis and grading of fatty liver is not well studied. The aim of the study was to investigate the value of DWI in the diagnosis and grading of hepatic steatosis in patients with NAFLD.Fifty-one adults (mean age: 38 years; 28 men, 23 women) with NAFLD, diagnosed clinically and by ultrasonography (USG), were included in the study after obtaining informed consent and approval from the institute ethics committee. USG was performed for grading of hepatic steatosis in all patients, followed by magnetic resonance imaging with DWI and MRS, on a 1.5T scanner. The mean apparent diffusion coefficient (ADC) values and proton density fat fraction (PDFF) were calculated, and MRS was used as the gold standard. The mean ADC values were compared with the PDFF and USG grades.There was a weak correlation between ADC values and PDFF (r = -0.36; P < 0.05). In addition, there was a weak correlation between the ADC values of the liver and USG grade (r = -0.34; P < 0.05). However, an overall increase in USG grades and PDFF was associated with decrease in the mean ADC value (P < 0.001).DWI is not accurate in the diagnosis and grading of hepatic steatosis in patients with NAFLD. However, a significant increase in fat deposition in the liver lowers the ADC values.