Abstract：Objective: To explore the relationship between ΔR2* value in oxygen-challenge blood oxygen level-dependent(BOLD) MRI and the severity of liver fibrosis in a rat model, and assess the potential value of diagnosis of the disease using ΔR2* value. Methods: Liver fibrosis was induced in 90 rats by means of weekly intraperitoneal injection with a mixture of carbon tetrachloride and olive oil. Ten healthy rats were used as controls. BOLD-MRI study was performed on the rats under anesthesia at steady normoxia state by inhaling room air and hyperoxia state by inhaling oxygen. The changes in R2* values(ΔR2*) during the oxygen challenge were quantified on the post-processing workstation. According to the pathological results, the rats were divided into three groups: A: without fibrosis(S0), B: mild and moderate fibrosis(S1~S2), C: severe fibrosis and cirrhosis(S3~S4). The differences of ΔR2* among the groups were tested by ANOVA and the correlation between liver fibrosis degree and ΔR2* were analyzed by Spearman-test. Results: Thirty-two liver fibrosis model rats and 10 healthy rats were performed BOLD-MRI. Absolute values of R2* decreased after oxygen challenge in all rats. A statistically significance(P<0.05) in ΔR2* were observed between group A((24.05±4.65) Hz), group B ((17.18±4.50) Hz) and group C((8.09±5.17) Hz). ΔR2* decreased during liver fibrosis progression and was negatively correlated with liver fibrosis degree(r=-0.827, P<0.001). Conclusion: ΔR2* in oxygen-challenge BOLD-MRI can reflect hemodynamic and oxygenation alterations during the progression of liver fibrosis, and has the potential to serve as a noninvasive method for liver fibrosis diagnosis and severity evaluation.
2013, Vol. 24 
