Background: This study aimed to compare the performance of gadoxetic acid -enhanced magnetic resonance imaging (MRI) and sonoelastography in evaluating chemopreventive effects of Sho-Saiko-To (SST) in thioacetamide (TAA)-induced early liver fibrosis in rats.
Materials and methods: Ten of Sprague-Dawley rats receiving TAA (200 mg/kg of body weight) intraperitoneal injection were divided into three groups: Group 1 (TAA only, n = 3), Group 2 (TAA +0.25 g/kg SST, n = 4) and Group 3 (TAA+1 g/kg SST, n = 3). Core needle liver biopsy at week 2 and liver specimens after sacrifice at week 6 confirmed liver fibrosis using histological examinations, including Sirius red staining, Ishak and Metavir scoring systems. Gadoxetic acid-enhanced MRI and shear-wave sonoelastography were employed to evaluate liver fibrosis. The expression of hepatic transporter organic anion transporter 1 (Oatp1), multidrug-resistant protein 2 (Mrp2) and alpha-smooth muscle actin (α-Sma) were also analyzed in each group by immunohistochemistry (IHC) and Western blot.
Results: According to histological grading by Sirius red staining, Ishak scores of liver fibrosis in Groups 1, 2 and 3 were 3, 2 and 1, respectively. As shown in gadoxetic acid-enhanced MRI, the ratio of relative enhancement was significantly lower in Group 1 (1.87 ± 0.21) than in Group 2 of low-dose (2.82 ± 0.25) and Group 3 of high-dose (2.72 ± 0.12) SST treatment at 10 minutes after gadoxetic acid intravenous injection (p < 0.05). Sonoelastography showed that the mean difference before and after experiments in Groups 1, 2 and 3 were 4.66 ± 0.1, 4.4 ± 0.57 and 3 ± 0.4 KPa (p < 0.1), respectively. Chemopreventive effects of SST reduced the Mrp2 protein level (p < 0.01) but not Oatp1 and α-Sma levels.
Conclusion: Sonoelastography and gadoxetic acid-enhanced MRI could monitor the treatment effect of SST in an animal model of early hepatic fibrosis.