The Usefulness of MRI R2* Value In Diagnosing And Staging of Rat Liver Fibrosis

Abstract

Background: Liver fibrosis involves the increase of iron deposition. however, whether R2* measurement can be used as a noninvasive method to characterize processes of fibrogenesis with iron deposition is not clear. This study aims at assessing the usefulness of magnetic resonance imaging (MRI) R2* value in diagnosing and staging of rat liver fibrosis. Methods: Male Sprague-Dawley rats were injected intraperitoneally with a mixture of 1.0 ml/kg carbon tetrachloride (CCl4) and oil (1:1 v/v) twice a week for 12 weeks. Liver R2* value was quantitatively determined by multi - echo fast gradient echo sequence. Liver iron content (LIC) was evaluated by an atomic absorption spectrophotometer. The stage of liver fibrosis was assessed by pathological METAVIR scores. The performances of R2* values for each fibrosis stage were evaluated. The receiver operating characteristic (ROC) curve analysis was used to determine the optimal cutoff values for fibrosis stage. Results: R2* values and LIC gradually increased during the progression of the liver fibrosis, the correlation between the R2* values and the LIC was high-positive. There were significant differences in R2* values among the stages of liver fibrosis (F= 30.84，P < 0.001). There was a significant positive correlation between R2* values and LIC (r= 0.984, P < 0.001). The most discriminating cutoff values of R2* were 46.84 Hz for ≥ F1, 55.30 Hz for ≥ F2, 68.06 Hz for ≥ F3, and 78.79 Hz for F4. Conclusion: R2* values can be used for detecting and staging liver fibrosis. The degree of liver fibrosis was related to the degree of increase in R2* measurements.