Quantitative analysis of susceptibility-weighted magnetic resonance imaging in chronic hepatitis in rats

Purpose: To assess the value of susceptibility-weighted imaging (SWI) for staging of liver fibrosis (F), necroin-flammatory activity (A), and steatosis (S) of chronic hepatitis. Methods: 100 Sprague-Dawley (SD) male rats were randomly divided into a chronic hepatitis model group (n = 88) and a control group (n = 12). The chronic hepatitis model rats were induced by intraperitoneal injection of 40% (v/v) of carbon tetrachloride (CCl4) diluted in olive oil. All rats were examined by magnetic resonance imaging (MRI) and then killed immediately to detect pathologic staging as liver fibrosis (F), necroin-flammatory activity (A), and steatosis (S). Liver-to-muscle signal intensity ratios (Sills) of SWI were analyzed and associated with histopathologic findings. Results: There were ultimately 11 normal control rats and 60 chronic hepatitis model rats. Statistical data were as follows: F0 (n = 11), Fl (n = 18), F2 (n = 16), F3 (n = 13), F4 (n = 13); AO (n = 11), Al (n = 29), A2 (n = 21), A3 (n = 10); SO (n = 11), S1 (n = 12), S2 (n = 12), S3 (n = 18), and S4 (n = 18). The liver-to-muscle SIR of the SWI was related to hepatic fibrosis (P < 0.05) and liver steatosis (P < 0.05) but not to necroinflammatory activity (P > 0.05). By partial correlation analysis, a significant negative correlation was shown between the liver-to-muscle SIR and staging of liver fibrosis (r = 0.68, P < 0.05) as well as a low correlation with liver steatosis (r = 0.30, P < 0.05). Except for F0-Fl and Fl F2, there were statistical differences between each of the stages of hepatic fibrosis (P < 0.05), with an area under the ROC of 0.87 for F3 or above and of 0.96 for F4. Conclusion: SWI can be a reliable method for staging hepatic fibrosis.