实验性蛋白多糖降解致兔膝关节软骨早期退变的核磁共振成像研究

目的　探讨低场磁共振成像 (MRI)在检测骨关节炎 (OA)早期软骨退变的表现及其价值。方法　选用新西兰大白兔 32只 ,右侧膝关节腔内注射 0 1ml木瓜蛋白酶溶液 (5U) ,建立OA早期软骨退变的动物模型。并在注药前及注药后 2 4、4 8、72h行双侧膝关节矢状面GE准T2 WI、SE T1WI、SE PDWI、SE T2 WI序列成像 ,取关节软骨组织作蛋白多糖含量测定和组织病理学检查。结果　注射木瓜蛋白酶后 2 4、4 8h ,关节软骨明显变薄 ,磁共振 (MR)信号强度明显降低。与对照组比较 ,两者差异均有显著性 (P <0 0 5 )。至注药后 72h关节软骨的厚度及信号强度已基本恢复正常。与对照组比较 ,两者差异无显著性 (P >0 0 5 )。关节软骨蛋白多糖含量测定及组织学检查结果表明 ,注射木瓜蛋白酶后 2 4、4 8h ,蛋白多糖含量明显降低 ,至注药后 72h ,蛋白多糖含量已逐渐恢复。软骨细胞均未见异常改变。结论　通过MR检查 ,可发现早期的软骨退变。

Magnetic resonance imaging reflects articular cartilage degeneration caused by proteoglycan depletion in the rabbit knee

Objective To study the appearance of magnetic resonance imaging (MRI) in early stages of cartilage degeneration and to detect its values.Methods Intra articular injection of 5 units of papain causing a reversible loss of cartilage proteoglycan in the New Zealand rabbit knees.Rabbits were scanned with magnetic resonance imaging,using a 0 3 T Hitachi magnet with 16 cm coil.Gradient echo sequences and spin echo sequences were performed in the sagittal planes at 0,24,48 and 72 hours after intra injection of papain.Then signal intensity and thickness of cartilage were measured.The proteoglycan content was measured biochemically and histochemically.Results The cartilage thickness and signal intensity decreased significantly in treated knees compared with control knees at 24 and 48 hours ( P <0 05),but without at 72 hours ( P >0 05) after injection of papain.These changes on magenetic resonance (MR) images were consistent with the changes of proteoglycan concentration measured by biochemical analysis and histochemical staining of cartilage.Conclusion It is possible for MRI to detect the early stages of cartilage degeneration.