Assessment of liver fibrosis: comparison of the liver fibrosis index by real-time ultrasound elastography and the apparent diffusion coefficient by magnetic resonance imaging in a rat model

Background: non-invasive method, apparent diffusion coefficient (ADC) and the liver fibrosis index (LFI), assessment of liver fibrosis has been one of major objectives in the society of hepatologists. Aim: To explore the variable characteristics of ADC and the LFI in different stages of liver fibrosis in rats and to compare their performance in staging liver fibrosis. Methods: Liver fibrosis model rats (N = 50) were produced by carbon tetrachloride (CCl4). Surviving model rats (N = 45) and controls (N = 15) were subjected to MRI and RTE, and the ADC and LFI values were analyzed. All animals were sacrificed for pathological examination. The liver fibrosis stage (F0-F4) was defined based on the METAVIR score. Nonparametric statistical methods and receiver operating characteristic (ROC) curve analyses were employed to determine diagnostic accuracy. Results: Correlation analysis showed that the liver fibrosis stage was negatively correlated with ADC (r = -0.732, P < 0.001) and positively correlated with LFI (r = 0.706, P < 0.001). ROC curves showed that the areas under the curve (AUCs) for ADC and LFI in the prediction of the liver fibrosis stage were 0.781-0.924 and 0.824-0.939, respectively. Conclusions: Both the ADC values and LFI values were strongly correlated with the liver fibrosis stages in our rat model. Moreover, the ADC was sensitive in predicting early-stage liver fibrosis, while the LFI was more accurate in predicting predict intermediate-and late-stage liver fibrosis.