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

To assess the value of susceptibility-weighted imaging (SWI) for staging of liver fibrosis (F), necroinflammatory activity (A), and steatosis (S) of chronic hepatitis.

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), necroinflammatory activity (A), and steatosis (S). Liver-to-muscle signal intensity ratios (SIRs) of SWI were analyzed and associated with histopathologic findings.

There were ultimately 11 normal control rats and 60 chronic hepatitis model rats. Statistical data were as follows: F0 (n = 11), F1 (n = 18), F2 (n = 16), F3 (n = 13), F4 (n = 13); A0 (n = 11), A1 (n = 29), A2 (n = 21), A3 (n = 10); S0 (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-F1 and F1-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.

SWI can be a reliable method for staging hepatic fibrosis.