肝纤维化磁共振灌注成像的初步实验研究

Assessment of liver fibrosis with perfusion-weighted MR imaging:preliminary study

目的:探讨大鼠化学性肝纤维化的MR灌注加权成像(PWI)表现,评价PWI对肝纤维化的诊断价值。方法:皮下注射CCl4建立大鼠肝纤维化模型(50只)和对照组(10只)进行MR-PWI扫描。按肝纤维化病理分期进行分组,采用方差分析比较各组间门静脉和肝实质灌注曲线的峰值时间、信号最大上升斜率和最大下降斜率的变化,分析各灌注参数与肝纤维化程度的相关性。结果:模型组38只和对照组10只共48只大鼠完成MR检查。病理分期S0(n=13)、S1(n=5)、S2(n=9)、S3(n=13)、S4(n=8)。S0期门静脉和肝实质的峰值时间[(15.03±1.05)s和(25.93±1.70)s],S1~S4期肝纤维化组的峰值时间逐渐递增[均值(26.29±3.52)s和(41.92±5.76)s],S0期与S2~S4期差异有统计学意义(P<0.05,<0.001,<0.001)。S0期门静脉和肝实质的最大上升斜率、最大下降斜率[门静脉(420.46±27.26)1/s和(193.50±16.76)1/s,肝实质(140.10±16.73)1/s和(121.00±15.16)1/s],S1~S4期肝纤维化组的最大上升、下降斜率逐渐递减[门静脉均值(292.61±40.02)1/s和(139.73±13.22)1/s,肝实质均值(76.70±9.55)1/s和(97.56±15.73)1/s],S0~S2期与S3、S4期差异有统计学意义(P<0.05)。峰值时间与肝纤维化分期呈显著正相关(P<0.01),最大上升斜率、门静脉的最大下降斜率与肝纤维化分期呈显著负相关(P<0.01)。结论:MR-PWI可以检测大鼠肝纤维化改变,可对中重度(S2~S4期)肝纤维化进行早期诊断。

Objective： To characterize liver perfusion in Wistar rats with experimental liver fibrosis by dynamic contrast- enhanced MRI and to correlate it with the severity of liver fibrosis. To evaluate the diagnostic efficacy of perfusion MR imag- ing for liver fibrosis. Methods： Mixed solution of CC14 and olive oil was hypodermically injected to fifty Wistar rats in the experimental group. Ten healthy rats served as control. MR perfnsion study with dynamic contrast-enhanced MRI was carried out on the rats under anesthesia. The rats were divided into S0-$4 stages according to the histological results of liver. Time to peak （TP）, wash-in rate and wash-out rate was compared between the groups using variance analysis, and the relationship between each perfusion parameters and severity of liver fibrosis were made by correlative analysis. Results： Forty-eight rats underwent MR perfusion study, including ten rats in the normal group. Histological results S0（n=13）, S1（n=5）, S2（n=9）, S3 （n=13）, S4（n=8）. On signal intensity time cnrve（Sl-T） derived from MR perfnsion weighted imaging（PWI）, TP of portal vein and liver in fibrotic group[mean, （26.29±3.52）s and （41.92±5.76）s] increased progressively compared with control group[mean, （15.03±1.05）s and （25.93±1.70）s]. S2-S4 stage can be distinguished from SO stage （P〈0.05, 〈0.001, 〈0.001, respectively）. Wash-in rate and wash-out rate of portal vein and liver in fil^rotic group[mean, PV（292.61±40.02）l/s and （139.73±13.22）1/s, liver （76.70±9.55）1/s and （97.56±15.73）1/s] decreased progressively compared with control group[mean, PV（420.46±27.26）l/s and （193.50±16.76）1/s, liver（140.10±16.73）l/s and （121.00±15.16）1/s]. s3 and s4 stage can be distinguished from S0-s2 stage（P〈 0.05）. TP value of the SI-T curve was significantly positive correlated to the severity of liver fibrosis （P〈0.01）. The wash-in rate and wash-out rate value were significantly negative correlated to the severity of liver fibrosis, respectively（P〈0.01）. Conclusion： MR-PWI has a potential in diagnosing and grading experimental liver fibrosis. PWI is an effective method to detect moderate and severe fibrosis（S2-S4 stage）.