Diffusion-weighted imaging of the liver in assessing chronic liver disease: effects of fat and iron deposition on ADC values.

Abstract

This study was designed to evaluate whether fat and iron affect the apparent diffusion coefficient (ADC) values of the liver parenchyma in the settings of fibrosis and inflammation. We evaluated the diffusion-weighted images (DWIs) of 58 patients with chronic liver disease and 48 control subjects. Liver specimens of patients were assessed for fibrosis, necroinflammation, iron, and steatosis. Liver ADCs, spleen ADCs, and normalized liver ADCs (defined as the ratio of the liver ADC to spleen ADC) values were analyzed after stratifying patients with either fibrosis stages or histology activity index (HAI) scores. The relationship between ADC values and histopathological findings was studied using multiple linear regression analysis. The median liver and normalized liver ADC values were significantly lower in higher stages of fibrosis and HAI scores. Compared to the control group, patients with the highest stages of fibrosis and inflammation had significantly higher spleen ADCs. The effect of the fibrosis stage on liver ADC and normalized liver ADC values was significant in the setting of inflammation, whereas the degree of steatosis and iron grade did not affect these ADC values. ADC values can distinguish both later stages of liver fibrosis and inflammation. There is no significant effect of fat and iron on ADC values. Therefore, DWI may be reliable in evaluating liver fibrosis and inflammation.