磁敏感加权成像在兔肝脏纤维化模型分期中的诊断价值

Value of susceptibility weighted imaging in hepatic fibrosis staging by using MR in a rabbit model

目的评价磁敏感加权成像（SWI）在家兔肝纤维化（HF）分期中的价值。方法60只实验兔按随机区组法分为3组：HF组（n=32）、对照组（n=16）、补充组（n=12）。HF组和补充组兔经皮下注射50％CCl4橄榄油溶液建立兔肝纤维化模型。注射后的第4、5、6、1、0周分别随机选HF组兔8只、对照组兔4只进行肝脏MRI轴位T1、WI、T2WI序列扫描及SWI扫描，扫描后处死并取兔肝组织进行Scheuer病理分期。在SWI图像上测量肝脏信号强度（SI肝）和同层背部肌肉的信号强度（SI肌），并计算二者信号强度比值（sIR肝／肌）。采用Spearman相关性检验分析SI肝、SIR肝／肌与组织病理分期之间的相关性。采用受试者工作特征（ROC）曲线分析SWI肝纤维化分期的诊断效能。结果共48只兔顺利完成磁共振扫描，病理分期FD组15只（16只对照组其中1只出现肝纤维化），其sIRMⅡ和sI#分别为0．9744-0．018、374士44；F1、2组、F3、4组各8只，其sIR旰／月n分别为0．963±0．018、0．796±0．023、0．786±0．025、0．5124-0．024，SI肝分别为372±18、3764-22、346±15、288±19。随着肝纤维化的进展，SIR忤／m值逐渐降低，sIR旰／目n与HF病理分期之间存在明显负相关性（r=-0．896，P〈0．05）。F3和F4期，SI肝值明显下降，差异有统计学意义（P〈0．05）。但FU与F1期，砣与F3期之间sIR旰／m值差异均无统计学意义（均P〉0．05）。ROC曲线分析显示sIⅡ值能鉴别F3期及以上的肝纤维化，而SIR肝／肌对各期肝纤维化有较高的诊断效能。结论SWI中sIR旰／n能定量反映肝纤维化的进展程度，为临床制定肝纤维化的治疗方案、疾病纵向观察提供一种客观、定量的影像学依据。

Objective To assess the feasibility of susceptibility weighted imaging （SWI） in staging hepatic fibrosis （HF）. Methods Sixty healthy rabbits were divided into three groups： HF group（ n = 32）, control group（ n = 16）, supplementary group（ n = 12 ）. Rabbits in HF group and supplementary group were injected subcutaneously with 50% CC14 oil solution to establish hepatic fibrosis model. On the basis of preliminary test, eight rabbits from HF group and four rabbits from control group underwent liver conventional MR scans and SWI once a time at 4, 5, 6, 10 weeks after CC14 administration. After MR scans at each time point, rabbits were killed to detect pathological staging with Scheuer staging. The liver signal intensity （SI） and liver-to-muscle SI ratios （SIR） were measured. According to the Scheuer classification of histological fibrosis stages, the correlation about the SI value, SIR value and the histological fibrosis stages was investigated by using the Spearman correlation test. The receiver operating characteristic （ ROC ） curve was used to evaluate the diagnostic performance of SWI for staging HF on the basis of the histopathologic analysis of HF. Results There were fifteen rabbits in pathological staging F0, the value of SIR and SI was 0. 974± 0. 018,374±44,SIR values of pathological staging from F1 to F4 were 0. 963 ±0. 018,0. 796 ± 0. 023,0. 786 ±0. 025,0. 512 ± 0. 024 respectively. SI values of pathological staging from F1 to F4 were 372 ±18,376 ± 22,346 ± 15,288 ± 19 respectively. In the early period of liver fibrosis, there were no statistical differences in the SI value between FO and FI, F1 and F2 stage. With progression of hepatic fibrosis, from F2 to F4, SI value decreased, the difference was statistically significant （ P 〈 0. 05 ）. With the progress of liver fibrosis, SIR value was reduced. It was negatively correlated with the HF stages and SIR value（r = -0. 896,P 〈0. 05）. ROC curve analysis showed that the efficiency of SI value diagnosis in liver fibrosis was high in the late stage of liver fibrosis, but it was low in the early stage. The performance of liver- to-muscle SI ratio on SWI was high in the early stage. Liver-to-muscle SI ratio had a higher diagnostic performance than SI in the diagnosis of liver fibrosis stages. Conclusion SWI can be a safe, reliable method for staging hepatic fibrosis and provide quantitative imaging basis for clinical treatment.