双能X线吸收法测定大鼠骨量的评价及去卵巢骨丢失敏感区的选择

Evaluation of rat bone mass measurement by dual-energy X-ray absorptiometry and determination of sensitive regions of bone loss in ovariectomized rat

目的 探讨双能X线吸收法 (DXA)测量大鼠骨密度 (BMD)的精密度和准确度及大鼠去卵巢后骨丢失的敏感区域。方法 用扇形束DXA(QDR45 0 0A)重复测量 16只SD大鼠不同骨胳区域BMD的变异系数 (CV)评价精密度 ;测量 40只大鼠骨矿含量 (BMC)与骨灰重比较评价准确度 ;与假手术组比较测定大鼠去卵巢后不同骨胳区域骨丢失率的变化选择骨丢失敏感区域。结果DXA测量BMD的CV为全身 (0 .71± 0 .44 ) % ,腰椎 (0 .82± 0 .5 3) % ,股骨 (0 .5 2± 0 .2 7) % ,胫骨(0 .81± 0 .11) % ,股骨和胫骨的各亚区 (1.46± 0 .2 6 ) % ;BMC与骨灰重呈高度正相关 (r =0 .984～0 .85 5 ) ,BMC显著低于骨灰重 (P <0 .0 0 1) ;生长期大鼠去卵巢 14周与假手术组BMD比较 ,腰椎(- 7.0 3% )、股骨远端 (- 9.0 3% )和近端 (- 7.49% )及胫骨近端 (- 11.7% )BMD显著减少 ,胫骨远端BMD显著增加 (8.82 % )。结论 DXA测量大鼠骨量是精密和有效的方法 ,胫骨近端干骺端和股骨远端干骺端是大鼠去卵巢后骨丢失最敏感区域。

Objective To prode into the precision of bone mineral density (BMD), the accuracy of bone mineral content (BMC) and the sensitive regions of interest (ROI) of bone loss in ovariectomized (OVX) rat by dual energy X ray absorptiome try (DXA). Methods The preicsion of variation coefficient (CV) in measurement of BMD at various skeletal regions was repeatedly determined in 16 SD rats by fan beam DXA. The accuracy of BMC by DXA measurements was assessed in comparison with thd ash weight at different skeletal sites in 40 SD rats. The change in bone loss rates was assessed at various skeletal regions by comparing the BMD of OVX and sham operated rats at 14 weeks and the sensitive regions of bone loss were chosen. Results The CVs for BMD measured by DXA were as follows, (0.71±0.44)% ( x ±s) for whole skeleton, (0.82±0.53)% for lumbar spine, (0.52±0.27)% for femur, (0.81±0.11)% for tibia, and (1.46±0.26)% for the regions of interest. There were highly significant correlations between in vitro DXA measurements of BMCs and ash weights of the femur, tibia and lumbar spine (r=0.984,r=0.970, and r=0.855 respectively). DXA measured BMCs at all skeletal sites were significantly lower than those of ash weights (P<0.001). AsignificantBMDdecreasewasrevealedatlumbarspine (-7.03%, P=0.014), distal femur (-9.03%, P<0.001), proximal femur (-7.49%, P=0.001), and proximal tibia (-11.7%, P<0.001) in OVX group at 14 weeks as compared with the sham operated group. However, the OVX group showed a significant increase in BMD at distal tibia (8.82%, P=0.006) as compared with sham operated rats. Conclusion The proximal tibia and distal femur are the most sensitive regions for detecting bone loss in ovariectomized rat by DXA.