应用磁共振软骨T2图成像定量测定退变兔膝关节软骨

目的:探讨T_2图成像技术在检测关节软骨退变早期的应用价值。材料和方法: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素和伊红染色(HE)、阿利辛兰染色(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24h、48h、72h先行相同常规磁共振成像及T_2图成像,取感兴趣点,测定关节软骨T_2弛豫时间值并取平均值,对每组数据进行t检验。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24h、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)。T_2图像软骨色阶由注射前的黄红色转为注射后的红色,注射木瓜蛋白酶后24h、48h、72h的T_2弛豫率分别升高了30.14ms,20.92ms和16.17ms。经t检验后,注射后24h与注射前差异具有统计学意义(P= 0.04,P<0.05)。结论:本研究采用的T_2图成像技术能够通过定量检测T_2弛豫时间值反映软骨退变早期软骨内的生化改变。

Application in Asaessment of Osteoarthritis in Rabbit Knee''s Articular Carrtilage with MR T2 Mapping

Purpose:To evaluate the value of T_2 mapping in articular cartilage of early osteoarthritis, we applied T2 mapping technique and measured articular cartilage of rabbit's knee of early osteoarthritis quantitatively.Materials and Methods:20 cases of New Zealand White rabbits were divided into 4 groups randomly.The left knees of the first group were scanned with conventional MR imaging,then were executed after MR imaging.The cartilage of femoral condyles were 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) 0.2ml.Every left knee of three groups were scanned by conventional MR imaging and T2 mapping before and after injection at 24h,48h and 72h respectively.T2 relaxation time of articular cartilage was calculated from dots of interest.Dif- ferences pre-and post-injection were analyzed with statistical analysis.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 of mean content of proteoglycan at 24h and 48h after injection of papain by compare with before injection (P=0.048 and 0.045 respectively,P<0.05).The difference was not statistically significant of the mean content of pro- teoglycan at 72h after injection of papain by compare with before (P=0.455,P>0.05).The cartilage's color of T2 map showed yellowish red before injection of papain to red after injection of papain.The T2 relaxation time was raised 30.14ms 20.92ms and 16.17ms after injection of papain at 24h 48h and 72h respectively.The difference at 24h was statistically significant by t-test(P=0.04,P<0.05).Conclu- sion:The T2 relaxation time came from T2 mapping can detect quantitatively biochemical change of ar- ticular cartilage in early osteoarthritis.