Diffusion-weighted Imaging Magnetic Resonance for Assessing Liver Fibrosis

Magnetic resonance (MR) imaging examination of liver will be performed on a 3.0T Achieva MR scanner (Philips Medical Systems, The Netherlands). Diffusion-weighted imaging (DWI) will be performed using a single-shot echo-planar imaging during a single end expiratory breath-hold. A single observer placed circular regions of interest around 2.30 cm2 to measure mean signal intensity (SI) in the right hepatic lobe and the spleen for each b value, avoiding areas of artifact, vessels, and focal lesions. A monoexponential fit will be performed to calculate liver and spleen apparent diffusion coefficient (ADC) on the basis of ln(SI) as a function of b value, using all b values. Normalized liver ADC will be calculated as the ratio of liver ADC to spleen ADC.