T2-mapping功能成像在兔膝关节内出血模型中显示出血后关节软骨异常的价值

T2-mapping Functional Imaging in Abnormal Articular Cartilage After Hemorrhage in Rabbit Knee Joint Hemorrhage Model

目的探讨T2弛豫时间图(T2-mapping)功能成像在兔膝关节内出血模型中显示出血后关节软骨异常的价值。材料与方法选取8月龄新西兰雄性大白兔15只,以兔右腿为模型侧,左腿为空白对照。从耳缘采自体静脉血2.5ml,注入关节腔,关节肿胀、关节腔内见暗红色积血,提示12只兔造模成功。在第1周和第2周末各重复注血1次,剂量同前。采用随机数字表法将12只兔随机分为两组,每组6只,分别于第4周、第8周行MRI扫描,动态监测双膝关节软骨变化,并于MRI检查后立即处死动物取材行病理检查观察软骨改变。MRI检查序列包括脂肪抑制的三维快速扰相梯度回波序列(3D-FS-SPGR)和T2-mapping。观察影像表现,测量并比较T2-mapping上T2值。结果第4周和第8周模型侧与对照侧相比,三维快速扰相梯度回波序列所示软骨未见明显差异,滑膜无明显增厚。第4周,模型侧T2-mapping伪彩图未见明显差异;第8周,模型侧T2-mapping伪彩图见股骨远端软骨正常的蓝绿色阶因软骨损伤而出现红黄色色阶。第4周和第8周,模型侧软骨T2值分别为(71.57±13.41)ms、(73.50±10.04)ms,对照侧分别为(59.09±2.90)ms、(56.01±6.47)ms,模型侧均高于对照侧,差异有统计学意义(P=0.029、0.001);模型侧第8周T2值较第4周升高,但差异无统计学意义(P=0.131)。结论兔膝关节内出血模型T2-mapping功能成像能早于形态学显示出血后关节软骨异常。

Purpose To explore the value of T2 relaxation time mapping(T2-mapping)functional imaging in evaluating abnormal articular cartilage after hemorrhage in rabbit knee joint hemorrhage model.Materials and Methods Fifteen New Zealand male white rabbits of 8 months old were selected,with the right leg as the model side and the left leg as the blank control.Autologous venous blood(2.5 ml)collected from the ear margin was injected into the joint cavity.Swollen joint and presence of dark red blood in the joint cavity suggested that the 12 rabbits were successfully modeled.The blood injection procedure was repeated at the end of 1st and 2nd week using the same dose.The 12 rabbit models were randomly assigned into two groups by randomized digital table,6 in each group.MRI scans were performed at the 4th and 8th week to dynamically monitor the cartilage changes of both knee joints.The animals were sacrificed immediately after MRI and pathological examination was performed to observe cartilage changes.The MRI sequences included threedimensional fat-suppressed spoiled gradient recalled echo(3D-FS-SPGR)sequence and T2-mapping.Based on image findings,the T2 value of T2-mapping was measured and compared.Results At the 4th and 8th week,no significant cartilage change or thickening of the synovial membrane in the 3D-FS-SPGR sequence was observed on the model side,compared with the control side.At the 4th week,there was no significant difference in the T2-mapping pseudo-color map;at the 8th week,the normal blue-green color of the distal femoral cartilage showed red-yellow color due to cartilage damage in the T2-mapping pseudo-color map of the model side.At the 4th and 8th week,the cartilage T2 value of the model side was respectively(71.57±13.41)ms and(73.50±10.04)ms,while of the control side was respectively(59.09±2.90)ms and(56.01±6.47)ms,with statistically significant differences(P=0.029 and 0.001,respectively).The T2 value of the model side at the 8th week was higher than that at the 4th week,but the difference was not statistically significant(P=0.131).Conclusion T2-mapping functional imaging can show abnormal articular cartilage earlier than morphology in rabbit knee joint hemorrhage model.