Increased Brownian Motion of Water Molecules in Livers With Advanced Fibrosis: Preclinical and Clinical Observations With Magnetic Resonance Imaging (MRI)

Despite the increased water content in fibrotic livers, numerous studies reported a decrease in apparent diffusion coefficient (ADC) in liver fibrosis. We argue that the ADC decrease in fibrotic livers is due to the “T2 shine-through” of ADC, as the longer T2 in liver fibrosis leads to less signal decay between the low and high b-value images. The metric slow diffusion coefficient (SDC), predominantly measuring Brownian motion of water molecules, was proposed to mitigate the difficulties associated with this “T2 shine-through” of ADC. This study calculated ADC and SDC of 1 rat study with liver fibrosis induced by biliary duct ligation (BDL), and 3 sets of human liver fibrosis data. To tease out the menopausal effect on liver SDC, only the results of men's livers were analyzed for the human datasets. The rat study showed that liver ADC decreased stepwise (in weeks after BDL procedure) following fibrosis induction, and SDC increased stepwise. In human studies, all 3 datasets consistently showed that advanced fibrosis had a liver ADC lower than that of earlier stage fibrosis; advanced fibrosis had a liver SDC higher than that of earlier stage fibrosis.