磁共振T_2-mapping成像在膝关节早期骨性关节炎中的应用

The Application of MRI T_2 mapping Imaging in the Early Osteoarthritis of the Knee

目的评价磁共振T2-mapping成像在膝关节早期骨性关节炎(osteoarthritis,OA)软骨损伤的应用价值。资料与方法采用Siemens 3.0 T磁共振,选取正常组[20名;年龄25～49岁,平均(40.1±6.5)岁]25个膝关节,根据国际软骨修复协会(ICRS)分级标准,选取早期OA组轻度软骨损伤者[32例;年龄39～60岁,平均(47.9±6.4)岁]35个膝关节,应用T2-mapping序列观察和测量两组股骨内外髁非负重区及负重区、胫骨内外平台、髌软骨共7处软骨的平均T2值,同时测量股骨内外侧髁非负重区与负重区软骨深浅层T2值,并进行统计学分析。结果早期OA组膝关节各部位软骨平均T2值均高于正常组,两组间比较差异有统计学意义(P值均<0.05);两组股骨内外髁负重区软骨T2值均要高于各自非负重区(P值<0.05);正常组股骨髁软骨浅深层T2值差异有统计学意义(P值<0.05);早期OA组股骨内外髁非负重区软骨浅层T2值明显高于深层(P值<0.05),负重区软骨浅层与深层比较差异无统计学意义(P值>0.05)。相应的T2图显示了T2值变化的趋势。结论磁共振T2-mapping成像可以量化评估无明显形态改变的关节软骨内组织成分的变化,对早期关节软骨损伤的诊断和监测具有较高的临床应用价值。负重对关节软骨T2值有一定影响。

Objective To evaluate the value of T2 mapping imaging in articular cartilage injury of early osteoarthritis of the knee.Materials and Methods T2 relaxation time of knee cartilage was evaluated with Siemens 3.0 T MR in 25 healthy knee joints（20 subjects,11 males and 9 females;age range：25-49 years,mean age 40.1±6.5 years） and 35 knee joints of early osteoarthritis（OA）（32 subjects,15 males and 17 females;age range：39-60 years,mean age 47.9±6.4 years） with an ICRS cartilage defect grade≤1.Morphological cartilage grading was based on conventional sequences.T2 values of seven compartments of knee cartilage including non weight bearing site and weigh bearing site of medial femoral condyle and lateral femoral condyle,medial tibia,lateral tibia and patella were measured respectively on T2 map imaging.The spatial variation in cartilage T2 value of femoral condyle was assessed.Statistical differences were analyzed.Results T2 value of diseased knees was significantly increased in all cartilage compartments compared with healthy group（P0.05）.There was a significant difference in T2 value of non weight bearing site and weight bearing site of medial and lateral femoral condyle for normal group as well as early OA group（P0.05）.Significant differences were found for the spatial variation in normal group（P0.05）.In early OA group,zonal variation was significant existed at the non weight bearing and weight bearing site（P0.05）.No significant differences were found between superficial and deep zone at the weight bearing site（P0.05）.Conclusion T2 mapping imaging of articular cartilage can monitor early cartilage degeneration prior to morphologic changes,which has a high value to diagnose and detect early cartilage injury in early stage of OA.The T2 value of cartilage is influenced by the weight bearing condition.