ABCB4 and Hepatic fibrosis: In this study we compared one of the standard models of liver fibrosis based on CCl4 intoxication with ATP-binding cassette transporter B4 knockout (Abcb4 −/−) mice, which develop sclerosing cholangitis and biliary fibrosis very similar to PSC in humans, in regard to tissue relaxation times assessed by MRR methods.