内侧半月板后角根部撕裂MRI各扫描方位诊断价值

Diagnostic value of MRI planes in medial meniscal root tear

目的研究膝关节内侧半月板后角根部撕裂在MRI不同扫描方位的诊断价值。方法收集我院经MRI检查,并经关节镜证实的32例内侧半月板后角根部撕裂资料进行分析;选取32例同年龄段的半月板其他节段损伤而无根部撕裂资料组进行对照。病例组分别在矢、冠、轴位图像上观察各扫描方位撕裂特征性征象,统计各扫描方位诊断的敏感性,特异性,阳性预测值和阴性预测值。结果 32例内侧半月板后角根部撕裂中,矢状位上主要表现为"鬼影征";冠状位主要表现为"截断征",具体各表现略有不同;轴位上主要表现为"钝圆征"或"裂隙征"。上述征象在病灶组均明显好发于对照组(P<0.05)。敏感性,特异性,阳性预测值和阴性预测值在病例组矢状位观察分别为:100%、80%、80%和100%;冠状位上分别为:100%、95%、93.8%和100%;轴位上为:93.8%、90.7%、90.9%和93.5%。结论 MRI扫描矢、冠、轴三个方位显示内侧半月板后角根部撕裂各有其特征性征象,明显好发于对照组。根部撕裂矢状位诊断的敏感性非常高,但会出现假阳性现象;冠状位敏感性同样非常高,而且诊断特异性优于矢状位;轴位图像是显示内侧半月板根部撕裂的容积形态的最好方位,但诊断价值受限于扫描到的半月板层数太少。

Objective To study the diagnosing value of various scanning planes of MRI in medial meniscal root tear. Methods MRI of 32 patients with arthroscopically confirmed posterior medial meniscal root tear was compared to that of 32 age-matched patients with medial meniscal tear not involving the root.The diagnostic sensitivity,specificity,positive predictive value and negative predictive value of root tear were calculated for sagittal,coronal,and axial planes.Results The characteristic“ghost”sign on sagittal,“truncation”sign on coronal,and“blunted”or“cleft”sign on axial MRI were significantly（P〈0.05）more common in root tear than meniscal tear not involving the root.On the sagittal,coronal and axial MRI,the sensitivities were 100%,100%, 93.8%;specificities were 80.0%,95.0%,90.7%;positive predictive values were 80%,93.8%,90.9%;and negative predictive values were 100%,100%,93.5%,respectively.Conclusion The MRI findings of medial meniscal root tear are characteristic in various scanning planes with high sensitivity in the sagittal and coronal planes,and highest specificity in the coronal plane.The axial plane is best for demonstrating the morphology of the tear with limitation of few slices depicting the menisci.