实验性化脓性关节炎关节软骨MRI改变与病理对照

目的对实验性化脓性关节炎的自然病程进行MR、组织病理学检查,以发现关节软骨在发生显著形态改变之前两者的内在联系.方法 40个犬膝关节为研究对象,随机选4个犬膝关节为正常对照,36个犬膝关节内分别注入108/ml金葡菌悬液2 ml,于注入菌液3、7、10、14、19、21、24、27、31天时对患病关节行MR检查.检查设备为GE Elscint Prestige 2.0 T超导型MR机.每个关节均行矢状面和冠状面T1加权,T2加权,质子密度加权,脂肪抑制T2加权成像,STIR序列.观察分析正常犬的8个关节面和患病犬的36个关节面的软骨形态,测量关节软骨的信号及厚度.MR检查后即刻处死动物,取关节上半部制成病理大切片行HE和甲苯胺兰染色.结果注入菌液7天开始软骨信号明显升高(P＜0.05).注入菌液19天开始软骨厚度较正常减小(P＜0.05).注入菌液7～31天,可见滑膜血管翳向关节软骨生长,关节软骨内见多形核细胞浸润.结论化脓性关节炎早期关节软骨的MRI表现是单纯的信号改变,化脓性关节炎后期软骨形态开始发生变化.关节软骨在MRI上信号和形态的改变能反映组织病理的变化.另外,软骨下骨的炎性浸润提示关节软骨的损伤.

Experimental MRI study of articular cartilage in pyogenic arthritis: correlated with histopathology

Objective To evaluate MR imaging in the early detection of articular cartilage involvement of pyogenic arthritis before the presence of significant morphology changes in experimental canine, correlated with histopathologic findings. Methods Forty canine knees were selected to perform the examination. Among them, four knees served as controls at random. Intraarticular injection of 2 ml of Staphylococcus aureus suspension (108 organisms/ml) was performed resqectively in all thirty-six knees. MR examinations using GE Elscint Prestige 2.0 T system were performed at 3,7,10,14,19,21,24,27 and 31 day respectively after the injection. Axial, saggital and coronal images were obtained with SE T1WI, FSE T2WI/PDWI, FS FSE T2WI, STIR. Signal intensity and thickness of cartilage were measured on all sequences. After animals sacrificed, the samples of femoral condyles were then fixed, decalcified, saggitally sectioned and stained with HE and toluidine blue. Results The diffuse increase of signal intensity of cartilage in pyogenic arthritis was present significantly at 7 days after intra-articular injection (P<0.05), while the decrease of thickness of cartilage after 19 days was present, compared with controls (P<0.05). Infiltration of mononuclear leukocyte, edema and necrosis of chondrocytes in deep zone adjacent to the bone were found. Conclusion Diffuse signal increase on FSE T2WI is the earliest sign of articular cartilage involvement in pyogenic arthritis.The changes of both signal intensity and morphology of articular cartilage can reflect histopathologic abnormality. In addition, inflammatory infiltration in subchondral bone is the early sign of adjacent cartilage injury.