磁共振延迟增强软骨成像在实验性关节软骨退变定量测定中的应用研究

Application of Quantitative Assessment in Experimental Articular Cartilage of Osteoarthritis with Delayed Gadolinium Enhanced MRI of Cartilage

目的探讨磁共振延迟增强软骨成像在检测关节软骨退变中的应用价值。方法选用20只新西兰大白兔,随机分为甲、乙、丙、丁四组。甲组左膝关节行常规磁共振成像,扫描结束后即刻处死,取股骨髁软骨行苏木精-伊红染色(HE)、阿利辛兰染色(Alcian Blue,AB)及蛋白多糖含量测定。乙、丙、丁各组每只兔左膝关节内注射0.2ml(10U)木瓜蛋白酶。乙、丙、丁各组于注射木瓜蛋白酶前及注射后分别于24、48、72h先行相同常规磁共振成像,后行磁共振延迟增强软骨成像(dGEMRIC),测定关节软骨T1驰豫时间值并取平均值。扫描结束后处死动物,取左膝股骨髁部软骨行大体观察、HE、AB染色及蛋白多糖含量测定。结果注射木瓜蛋白酶后24、48h,蛋白多糖含量与甲组比较,统计学均有差异(P=0.048和0.045,P<0.05),注射后72h,统计学没有差异(P=0.455,P>0.05)。T1map图像软骨色阶由注射前的粉红色转为注射后的蓝色,注射木瓜蛋白酶后24、48、72h的T1弛豫率分别降低了316.09ms、244.01ms和143.98ms。经t检验,注射后24、48h与注射前比较有统计学差异(P=0.047和0.045,P<0.05)。结论本研究采用的dGEM-RIC成像技术能够通过定量检测T1弛豫时间值反映软骨退变早期软骨内的生化改变。

Objective To evaluate the value of delayed gadolinium enhanced MRI of cartilage （dGEMRIC） in articular cartilage of early osteoarthritis. Methods Twenty eases of New Zealand white rabbits were divided into 4 groups randomly. The left knee of the first group was scanned with conventional MR imaging, and then were executed after MR imaging. The cartilage of femoral condyles was examined by hematoxylin and eosin （HE） staining and alcian blue （AB） staining and were assessed for proteoglycan. Every left knee of the second to the fourth group was injected with PaPain （10units/knee） 0.2 ml. Every left knee of three groups was scanned by conventional MR imaging and dGEMRIC imaging before and after injection at 24 h, 48 h and 72 h respectively. Tl relaxation time of articular cartilage was calculated from dots of interest. All rabbits were executed after MR imaging, left cartilage of femoral condyles were examined by HE staining and AB staining and were assessed for Proteoglycan. Results The differences were statistically significant in mean content of proteoglycan between at 24 h and 48 h after injection and before injection of PaPain （P=0.048 and 0.045 respectively ,P〈0.05）. The difference was not statistically significant in the mean content of Proteoglycan between at 72 h after injection and before injection of PaPain （P=0.455 ,P〉 0.05）. The cartilage＇s color of T2 map showed Pink before injection of PaPain to blue after injection. The TI relaxation time was decreased 316.09 ms, 244.01 ms and 143.98 ms after injection of PaPain at 24 h 48 h and 72 h respectively. The differences at 24 h and 48 h were statistically significant by t-test （P=0.047 and 0.045 ,P〈0.05）. Conclusion The T1 relaxation time from dGEMRIC imaging can detect quantitatively biochemical change of articular cartilage in early osteoarthritis.