Diagnosis of Liver Pathologies Based on Apparent Diffusion Coefficient of Magnetic Resonance Diffusion-Weighted Imaging in a Rabbit Model of Liver Fibrosis

OBJECTIVE:To assess the value of apparent diffusion coefficient (ADC) of magnetic resonance diffusion-weighted imaging (MR-DWI) for diagnosis of the liver pathologies in rabbit model of liver fibrosis.METHOD:MR-DWI with four different b values (200, 500, 300 and 600 s/mm(2)) was performed in 4 normal New Zealand white rabbits and 13 rabbits with experimental liver fibrosis. For each rabbit, 4 ADC values were obtained in the left and right lobes of the liver. According to the ISHAK criteria of liver histopathological scoring and fibrosis staging system, all the liver specimens were histopathologically graded (scores 1-6 for grade I, 7-12 for grade II, and 13-18 for grade III) and assessed for fibrosis staging (stages I to VI). The variation of ADC values were analyzed based on the results of histopathological grading and fibrosis staging.RESULTS:The 4 ADC values were obviously lower in rabbits with liver fibrosis than in the normal control rabbits. Statistical analysis showed significant differences in the ADC values between the normal control and liver fibrosis groups, and between the rabbits with different histopathological grades and fibrosis stages (P=0.000).CONCLUSIONS:Liver fibrosis results in significantly lowered ADC values of the liver depending on the histopathological grades and fibrosis stages. The pathological basis for these changes lies in reduced water content and restricted Brownian motion of water in the liver due to hepatocyte degeneration and swelling, inflammatory cell infiltration, and collagen fiber deposition in the interstitial space.