Intravoxel incoherent motion parameters in the evaluation of chronic hepatitis B virus-induced hepatic injury: fibrosis and capillarity changes

Objective To evaluate the diagnostic efficacy of intravoxel incoherent motion (IVIM) parameters in hepatitis B virus (HBV)-induced hepatic fibrosis using different calculation methods and to investigate histopathologic origins. Materials and methods Liver biopsies from 37 prospectively recruited chronic hepatitis B patients were obtained. Twelve b -value (0–1000 s/mm 2 ) diffusion-weighted imaging (DWI) was performed with a 1.5 T scanner and was followed by blinded percutaneous liver biopsy. All biopsy specimens were evaluated with Ishak staging, and the microvascular density (MVD) was calculated. Patients were classified as having no/mild (F0–1), moderate (F2–3), or marked (F4–5) fibrosis. Pseudodiffusion ( D *), the perfusion fraction ( f ), and the apparent diffusion coefficient (ADC) were calculated using all b -values, while true diffusion ( D ) was calculated using all b -values [ D 0–1000 ] and b -values greater than 200 s/mm 2 [ D 200 – 1000 ]. Three concentric regions of interest (ROIs) (5, 10, and 20 mm) centered on the biopsy site were used. Results D* was correlated with the MVD ( p = 0.015, Pearson’s r = 0.415), but f was not ( p = 0.119). D 0–1000 was inversely correlated with Ishak stage ( p = 0.000, Spearman’s r s = − 0.685) and was significantly decreased in all the fibrosis groups; however, only the no/mild and marked fibrosis groups had significantly different D 200–1000 values. A pairwise comparison of receiver operating characteristic (ROC) curves of D 0–1000 and D 200-1000 showed significant differences ( p = 0.039). D * was the best at discriminating early fibrosis (AUC = 0.861), while the ADC best discriminated advanced fibrosis (AUC = 0.964). Conclusion D * was correlated with the MVD and is a powerful parameter to discriminate early hepatic fibrosis. D significantly decreased with advanced fibrosis stage when using b -values less than 200 s/mm 2 in calculations.