Bone mineral determination using dual photon absorptiometry

为了定量测定椎体骨密度（BMD），研制了基于伽玛相机的高精度双光子吸收仪（DPA），并进行了临床研究。正常女性的骨密度随年龄增长而下降，尤其是绝经后，以皮质骨（第2掌骨和1/3桡骨远端）为主的尾骨和以小梁骨（腰椎整体骨或小梁骨）为主的中轴骨。此外，与男性相比，女性的骨质流失发生得更早，程度也更严重。轴骨的骨丢失发生时间和速率比尾骨更早、更突出。骨密度值与甲状旁腺激素浓度之间没有高相关性。骨密度低的少数病例骨组织形态测定显示为低翻转骨型。因此，可以预期，骨矿物质测定在早期诊断、骨折风险预测和骨质疏松症的治疗反应方面是有用的，骨质疏松症在日本的发病率将在未来增加。慢性肾衰竭时，椎体骨密度值由低到高分布，1 ~ 5年出现高骨密度。-透析史或轻度继发性甲状旁腺功能亢进症（SHP），而在超过5年的病例中观察到低的桡骨骨密度。-有严重的SHP病史。此外，桡骨和椎体骨密度值的差异，例如。桡骨低椎体高，已被确认。这些结果表明，为了阐明肾性骨营养不良的骨病理生理，测量皮质骨和小梁骨的骨密度是必要的。

In order to quantifying the vertebral bone mineral density(BMD), highly accurate and precise dual photon absorptionmetry(DPA) system using gamma camera was developed, and clinical study was done. In normal females the BMDs in both appendicular bone, mainly consisted of cortical bone(2nd metacarpal bone and 1/3 distal radius), and axial bone, mainly composed of trabecular bone(integral or trabecular bone of lumbar betebra), decreased with aging, especially in post-menopause. Furthermore, the bone loss in females occurred earlier in life and more severe in its grade than that in males. Also, the initiation and the rate of bone loss in axial bone were earlier and more prominent than appendicular bone. No high relation between BMD values and PTH concentrations was observed. The bone histomorphometry wich was performed in few cases with low BMD values showed the low turn-over bone type. Thus, it would be expected that the bone mineral determination was useful in the early diagnosis, the anticipation of fracture risk and the therapeutical response of osteoporosis, which would be increasing in the incidence in Japan in future.In chronic renal failure, the vertebral BMD values distributed from low to high, and high vertebral BMDs were observed in cases with 1-5 yrs.-history of dialysis or mild secondary hyperparathyroidism(SHP), while the low radial BMDs were observed in cases with more than 5 yrs.-history or severe SHP. Furthermore, the discrepancy of radial and vertebral BMD values, eg. low in radius and high in vertebra, was recognised. These results indicate that, to clarify the bone pathophysiology in renal osteodystrophy, the measurement of BMD in both cortical and trabecular bone is essential.