不同b值DWI对大鼠肝纤维化、肝硬化病理分级的意义

Significance of diffusion-weighted imaging with different b values in pathological grading of hepatic fibrosis and cirrhosis of rats

目的：探讨1.5 T MRI不同b值DWI下的ADC值、e ADC值与大鼠肝纤维化、肝硬化分级的相关性。方法：清洁级SD大鼠100只,雄性,体质量180~200 g。将大鼠随机分为实验组84只,对照组16只,实验组采用硫代乙酰胺（TAA）腹腔定点注射,对照组同期腹腔注射同剂量生理盐水。常规MRI检查后,DWI采用FSE-EPI,按b=300、600 s/mm2分为2组,生成ADC图及e ADC图,并测量相应ADC及e ADC值;根据病理结果将肝损伤分为肝纤维化0期（对照组）、肝纤维化I~Ⅱ期（早期）、肝纤维化Ⅲ~Ⅳ期（晚期）、肝硬化结节期。结果：共59只（实验组47只,对照组12只）大鼠成功行DWI检查。1b=300 s/mm2时,实验组ADC值均低于对照组,对照组与实验组各期之间及肝硬化结节期与其余各组之间差异均有统计学意义（均P〈0.05）;e ADC值均高于对照组,肝硬化结节期与其余各组间差异均有统计学意义（均P〈0.05）,对照组与肝纤维化晚期组之间差异有统计学意义（P〈0.05）。b=600 s/mm2时,实验组ADC值均低于对照组,肝硬化结节期与其余各组间差异有统计学意义（均P〈0.05）,对照组与肝纤维化晚期组之间差异有统计学意义（P〈0.05）;肝硬化结节组e ADC值与各组两两比较差异均有统计学意义（P〈0.05）。2ADC值与SD大鼠肝纤维化、肝硬化病理分级之间呈负相关,b=300 s/mm2时,r=-0.463（P〈0.05）;b=600 s/mm2时,r=-0.606（P〈0.05）。e ADC值与SD大鼠肝纤维化、肝硬化病理分级之间呈正相关,b=300 s/mm2时,r=0.504（P〈0.05）;b=600 s/mm2时,r=0.435（P〉0.05）。结论：ADC值和e ADC值能对肝纤维化、肝硬化进行分级,且有一定的相关性。b=600 s/mm2时,ADC值与肝纤维化、肝硬化分级之间相关性最好。

Objective：To evaluate the correlation between pathological grading of rat liver fibrosis and cirrhosis and the value of both ADC and eADC of MR-DWI using different b value. Methods ：100 clean male SD rats,weight 180--200 g. All rats were randomly divided into the experimental group （n=84）,and the control group （n=16）. The experimental group was injected intraperitoneally with thioacetamide （TAA）,and the control group was injected with the same dose of saline in the same way. After MR routine scanning,diffusion weighted imaging （DWI） was applied using FSE-EPI,with b=300,600 s/mm2 respectively,to generate the ADC and eADC maps and measure ADC and eADC values accordingly. According to pathological results,liver damage can be divided into fibrosis stage 0, Ⅰ --Ⅱ （early stage）, Ⅲ- Ⅳ（advanced stage） and cirrhosis nodules stage. Results： DWI images were successfully obtained from 59 rats （the control group 12,the experimental group 47）.①When b=300 s/ram2 was applied,ADC values of the experimental group were lower than the control group. There were significant differences of both the value of ADC among control group and experimental groups and the value of ADC among cirrhosis nodules stage and the other groups （P〈0.05）. The eADC values of the experimental group were higher than the control group. There were significant differences of the value of ADC among cirrhosis nodules stage and the other groups （P〈0.05）,while differences were found between the control group and advanced stage （P〈0.05）. When b=600 s/mm2 was applied,there were significant differences of the value of ADC among cirrhosis nodules stage and the other groups （P〈0.05）,while differences were found between the control group and advanced stage （P〈0.05）. There were significant differences of the value of eADC among cirrhosis nodules stage and the other groups （P〈0.05）. ②ADC values were negatively correlated with pathological grading of hepatic fibrosis and cirrhosis of rats （b=300 s/mm2：r=-0.463,P〈0.05;b=600s/mm2：r=-0.606,P〈0.05）, eADC values were positively correlated with pathological grading of hepatic fibrosis and cirrhosis of rats （b=300 s/ram2：r=0.504,P〈0.05 ;b=600 s/ram2;r=0.435,P〉0.05）. Conclusion：ADC and eADC values may be used to stage the hepatic fibrosis and cirrhosis,because of the good correlation between the hepatic fibrosis and ADC and eADC values. When b=600 s/mm2 was applied,ADC values were most correlated with pathological grading of hepatic fibrosis and cirrhosis of rats.