DXA测定大鼠离体骨骨密度的精确性及其初步应用

目的探讨应用双能X线吸收法(DXA)骨密度仪测量大鼠离体骨骨密度(BMD)的精确性及其实用性。方法用DXA骨密度仪(NorlandExcellplus)重复测量10只Wistar大鼠离体的第5腰椎、双侧股骨BMD,获得其批内、批间变异系数(CV);测量90只Wistar大鼠离体的未去椎弓及去椎弓的第5腰椎、双侧股骨的BMD;测量去卵巢(Ovx)与假手术(Sham)大鼠离体的未去椎弓及去椎弓的第5腰椎、双侧股骨的骨密度。结果(1)各离体骨BMD值的批内CV:腰椎为1.58%、左侧股骨为0.90%、右侧股骨为0.86%;上述相应各部位的批间CV分别为2.22%、1.09%和1.20%;(2)DXA测量90只大鼠未去椎弓及去椎弓的腰椎、左侧股骨、右侧股骨的BMD值分别为(127.5±12.3)、(82.6±11.3)、(150.7±10.6)及(149.9±10.6)mg/cm2,左右股骨BMD值的相关系数为0.792(P<0.001);(3)去卵巢18周组与同龄假手术组BMD值比较,去椎弓的第5腰椎、左右两侧股骨远端干骺端的骨丢失率较大,下降率为10.0%～17.5%。结论以NorlandExcellplus型DXA测量大鼠离体骨的骨密度,其精确性良好,能较敏感地反映大鼠骨量的变化。

Precision of rat BMD measurements by dual-energy X-ray absorptiometry in vitro

OBJECTIVE: To evaluate the precision of rat bone mineral density (BMD) measurements by Norland Excellplus dual-energy X-ray absorptiometry (DXA) and to investigate the BMD changes in ovariectomized (Ovx) rats in vitro. METHODS: (1) The coefficients of variation (CV) for BMD measurements at various skeletal regions were repeatedly determined by DXA in 10 Wistar rats in vitro. (2) BMD in lumbar vertebra (L5) and both sides of femurs was measured in total 90 rats. And (3) changes in BMD between Ovx and sham rats were compared. RESULTS: (1) The short-term CVs of BMD measurements in different regions by DXA were as follows, 1.58% for lumbar vertebra (L5), 0.90% for left femur, and 0.86% for right femur, respectively. The long-term CVs were 2.22% for lumbar vertebra (L5), 1.09% for left femur, and 1.20% for right femur. (2) The BMD values in 90 Wistar rats were (127.5 +/- 12.3) in lumbar vertebra (L5), (82.6 +/- 11.3) in corpus vertebra (L5'), (150.7 +/- 10.6) in left femur and (149.9 +/- 10.6) mg/cm2 in right femur, respectively. The correlation coefficient of BMD measurements between left and right femurs was 0.792 (P < 0.001). (3) In Ovx group, the BMD values of corpus vertebra (L5') and distal femurs were significantly decreased, that was 10.0%-17.5% lower in comparison with sham group (P < 0.001). CONCLUSIONS: Measurement of rat BMD in vitro by Norland Excellplus DXA is a useful method, and it can reflect the changes in rat bone masses with good precision.