Liver intravoxel incoherent motion diffusion-weighted imaging for the assessment of hepatic steatosis and fibrosis in children

AIM To evaluate the correlation between intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) parameters and the degree of hepatic steatosis and fibrosis in children. METHODS This retrospective study was approved by the institutional review board. The children (<= 18 years) who underwent liver IVIM DWI with 8 b-values under 20the suspicion of hepatic steatosis or fibrosis from February 2013 to November 2016 were included. Subjects were divided into normal, fatty liver (FAT), and fibrotic liver (FIB) groups. The slow diffusion coefficient (D), fast diffusion coefficient (D*), perfusion fraction (f), and apparent diffusion coefficient (ADC) were measured. MR proton density fat fraction (PDFF), MR elastography (MRE), and IVIM values were compared. RESULTS A total of 123 children (median age of 12 years old, range: 6-18 years) were included, with 8 in the normal group, 93 in the FAT group, and 22 in the FIB group. The D* values were lower in the FIB group compared with those of the normal (P = 0.015) and FAT (P = 0.003) groups. The f values were lower in the FIB group compared with the FAT group (P = 0.001). In multivariate analyses, PDFF value was positively correlated with f value (beta = 3.194, p < 0.001), and MRE value was negatively correlated with D* value (beta = -7.031, P = 0.032). The D and ADC values were not influenced by PDFF or MRE value. CONCLUSION In liver IVIM DWI with multiple b-values in children, there was a positive correlation between hepatic fat and blood volume, and a negative correlation between hepatic stiffness and endovascular blood flow velocity, while diffusion-related parameters were not affected.