常规MRI在骨质疏松诊断中的价值

The value of routine MRI examination for evaluating osteoporosis

目的探讨常规MRI中T2加权成像(T2-weighted imaging,T2WI)及频率选择饱和法(frequency-selective saturation,FS)脂肪抑制T2WI序列在评估骨质疏松中的价值。材料与方法收集重庆医科大学附属大学城医院行腰椎MRI及双能X线吸收法(dual-energy X-ray absorptiometry,DXA)骨密度测定的88例受检者资料,根据DXA骨密度结果分为正常组、骨质减少组及骨质疏松组,另外,骨质减少组与骨质疏松组又归为骨质异常组。分析腰1至腰4椎体矢状面T2WI及FS-T2WI的信号强度差值在各组间的差异及对骨质异常的诊断效能。结果各组信号差值分别为:正常组为103.95±34.08,骨质减少组为193.46±38.35,骨质疏松组为206.80±34.72,骨质异常组为202.65±35.99。正常组、骨质减少组、骨质疏松组三组间差异有统计学意义(F=88.19,P<0.01),骨质减少组与正常组间差异有统计学意义(P<0.01),骨质疏松组与正常组间差异有统计学意义(P<0.01),骨质减少组与骨质疏松组间差异无统计学意义(P=0.24);正常组与异常组间差异有统计学意义(P<0.01)。信号差值=156.15时,区分骨质正常与异常的ROC曲线下面积最大,为0.983,敏感度和特异度分别为93.3%、93.0%。结论常规MRI T2WI及FS-T2WI图像信号差值能通过检测骨髓脂肪组织含量间接反映骨质情况,对骨质疏松的诊断具有提示意义。

Objective:To explore the value of routine MRI T2-weighted imaging(T2WI)and frequency-selective saturation(FS)T2WI in evaluating osteoporosis.Materials and Methods:88 cases were collected whose lumbar spine bone mineral density was determined by dual-energy X-ray absorptiometry(DXA)and MRI within 1 month.According to the results of lumber DXA,cases were divided into normal bone mass group,osteopenia group and osteoporosis group,osteopenia group and osteoporosis group were classified as abnormal bone mass group.MRI mean signal difference of 1-4 lumbar vertebrae in the sagittal plane T2WI and FS-T2WI among three group and the diagnostic efficacy value between normal and abnormal bone mass group were analyzed.Results:The mean signal intensity difference of normal bone mass group,osteopenia group,osteoporosis group and abnormal bone mass group were 103.95±34.08,193.46±38.35,206.80±34.72,202.65±35.99 respectively.The difference among the three groups were statistically significant(F=88.19,P<0.01).The difference between normal bone mass group and osteopenia group was statistically significant(P<0.01).The difference between normal bone mass group and osteoporosis group was statistically significant(P<0.01).The difference between osteopenia group and osteoporosis group was of no statistically significant(P=0.24).The difference between normal and abnormal bone mass group was statistically significant(P<0.01).When the mean signal intensity difference was 156.15,the largest area under the ROC curve was 0.983,with the sensitivity of 93.3% and specificity of 93.0%.Conclusions:MRI mean signal intensity difference of lumbar vertebrae in T2WI and FS-T2WI can indirectly reflect the bone metabolism by detecting the content of bone fat,it has important significance to evaluate osteoporosis.