双能X线吸收测量法在慢性脊髓损伤患者腰椎骨密度丢失评价中的应用

Dual-energy radiographic absorptiometry in estimation of bone loss of lumber vertebra in patients with spinal cord injury

目的评价双能X线吸收测量法（DEXA）腰椎正位和侧位测定慢性脊髓损伤患者腰椎骨密度的价值。方法采用DEXA检测9例四肢瘫痪和6例截瘫患者正位及侧位腰椎和全髋关节骨密度。结果患者平均年龄是（35±15）岁（20-62岁）,损伤时间为（57±74）个月（53-200个月）。腰椎侧位骨密度T评分和Z评分高于正位[T评分L2：（20.7±1.2）vs（0.0±1.4）,P=0.01;L3：（20.9±1.6）vs（0.3±1.3）,P=0.002;L2-L3：（20.8±1.3）vs（0.2±1.3）,P=0.001;Z评分L2：（20.3±1.1）vs（0.2±1.2）,P=0.05;L3：（20.6±1.3）vs（0.5±1.3）,P=0.01;L2-L3：（20.4±1.1）vs（0.4±1.2）,P=0.005]全髋关节T评分、Z评分[分别为（21.1±1.0）和（21.0±1.0）]和L2-L3腰椎侧位评分类似,而L2-L3腰椎正位评分维持不变。随脊髓损伤时间增加,腰椎侧位骨密度显著下降,而腰椎正位骨密度保持不变。结论 DEXA检测腰椎侧位骨密度能够准确反映脊髓损伤患者骨密度丢失情况,而腰椎正位骨密度检测不能准确反映骨密度丢失情况,可能会低估患者骨折发生风险。

【Objective】 To determine bone mineral density（BMD） of the L-spine by PA and lateral（LAT）dual-energy radiographic absorptiometry（DEXA） in patients with chronic spinal cord injury（SCI）. 【Methods】Measurements of the PA and LAT L-spine and hip were performed in 15 patients with SCI（9 with tetraplegia and 6 with paraplegia）. The DEXA（GE Lunar Advance DEXA） images were obtained using standard software. Results were reported as mean ± SD.【Results】 The mean age was（35 ± 15） years（range： 20-62 years）,and the duration of injury was（57 ± 74） months（range： 53-200 months）. T- and Z-scores for BMD were higher for the LAT L-spine than those for PA L-spine [T-scores for L2：（20.7 ± 1.2） vs（0.0 ± 1.4）, P = 0.01;L3：（20.9 ± 1.6） vs（0.3 ± 1.3）, P = 0.002;L2-L3：（20.8 ± 1.3） vs（0.2 ± 1.3）, P = 0.001;Z-scores for L2：（20.3 ± 1.1）vs（0.2 ± 1.2）, P = 0.05;L3：（20.6 ± 1.3） vs（0.5 ± 1.3）, P = 0.01; L2-L3：（20.4 ± 1.1） vs（0.4 ± 1.2）, P = 0.005].The T- and Z-scores for the total hip [（21.1 ± 1.0） and（21.0 ± 1.0）, respectively] and L2-L3LAT L-spine demonstrated remarkable similarities, whereas the L2-L3PA L-spine scores were not reduced. Bone mineral density of the LAT L-spine, but not the PA L-spine, was significantly reduced with increasing duration of injury. 【Conclusions】 Individuals with SCI may have bone loss of the L-spine that is evident on LAT DEXA but may be misdiagnosed by PA DEXA which may lead to underestimation of the potential risk of fracture.