Quantification of Liver Fibrosis at T1 and T2 Mapping with Extracellular Volume Fraction MRI: Preclinical Results

Purpose: To evaluate MRI T1 and T2 mapping with calculation of extracellular volume (ECV) for diagnosis and grading of liver fibrosis. Materials and Methods: Different grades of fibrosis were induced in 60 male Sprague-Dawley rats by bile duct ligation (BDL) and carbon-tetrachloride (CCl4) intoxication. Portal pressure was measured invasively, whereas hepatic fibrosis was quantified by hydroxyproline content, Sirius red staining, and a smooth muscle actin staining. T1 values, T2 values, and ECV were assessed by using quantitative MRI mapping techniques. Results: T1 values in animals 4 weeks after BDL were greater than in control animals (718 msec +/- 74 vs 578 msec +/- 33, respectively; P<.001). T2 values at 4 weeks were also greater in animals that underwent BDL than in control animals (46 msec +/- +/- vs 29 msec +/- 2, respectively; P<.001). Similar T1 and T2 findings were observed after CCl4 intoxication. ECV was greater in animals 4 weeks after BDL compared with control animals (31.3% +/- 1.3 vs 18.2% +/- 3.5, respectively; P<.001), with similar results after CCl4 intoxication. High correlations were found between ECV and hepatic hydroxyproline content (BDL: r = 0.68, P<.001; CCl4 : r = 0.65, P<.001), Sirius red staining (BDL: r = 0.88, P<.001; CCl4 : r = 0.82, P<.001), a smooth muscle actin staining (BDL: r = 0.70, P<.001; CCl4 : r = 0.73, P<.001), and portal pressure (BDL: r = 0.54, P =.003; CCl4 : r = 0.39, P =.043). Conclusion: Elevation of T1 and T2 values and ECV was associated with severity of liver fibrosis and portal hypertension in an experimental animal model. (C) RSNA, 2018