Department of Nuclear Medicine, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY 10467, USA.
Semin Nucl Med. 2011 May;41(3):220-8. doi: 10.1053/j.semnuclmed.2010.12.002.
Conventional radiographic methods allow physicians to visualize bone structure. However, they do not offer information on the bone mineral density (BMD), which can facilitate early diagnosis and treatment of osteoporosis. Bone densitometry, by contrast, helps to detect bone mineral loss at an early stage because it provides accurate quantitative measurement of BMD. With an emphasis on quantification, shorter scanning time and precision, scientists have been developing BMD measurement devices that use absorption technique. They first developed single-energy absorptiometry (single-photon absorptiometry) by using I-125, which could measure BMD of peripheral bones. Single-photon absorptiometry was replaced by dual-energy absorptiometry (dual photon absorptiometry [DPA]) that used gadolinium-153. DPA had greater accuracy in measuring the BMD of central skeletal bones. Single-energy x-ray absorptiometry was also developed but it had limitations in measuring central skeletal BMD. In the mid-1980s, dual-energy x-ray absorptiometry (DXA) was introduced and widely accepted for the early detection, treatment, and follow-up study of osteoporosis. There are several reasons for the popularity. DXA can measure BMD of posteroanterior spine and hip in a much shorter time than DPA while being capable of measuring BMD of peripheral bones. Other advantages include very low radiation doses to the patients, high image resolution, precision, and stable calibration of the instruments. In recent years, DXA has also been applied to lateral spine for the density of trabecular bone, to the whole body for the measurement of total body bone density and for the body composition, and to the spine for the vertebral fracture assessment. Still, posteroanterior spine and hip scans remain the most common applications of DXA because data on the normal range of BMD of the skeletal sites for different age, sex, and ethnic groups are compiled and made available with the devices, which gives the physician the advantage of an immediate diagnosis.
传统的放射学方法可以使医生观察到骨骼结构。然而，它们并不能提供有关骨矿物质密度（BMD）的信息，而 BMD 有助于早期诊断和治疗骨质疏松症。相比之下，骨密度测定有助于在早期发现骨矿物质流失，因为它可以对 BMD 进行准确的定量测量。由于强调定量、缩短扫描时间和提高精度，科学家们一直在开发使用吸收技术的 BMD 测量设备。他们首先开发了单能吸收法（单光子吸收法），使用 I-125 测量外周骨骼的 BMD。单光子吸收法被双能吸收法（双光子吸收法[DPA]）取代，后者使用钆-153。DPA 在测量中央骨骼 BMD 方面具有更高的准确性。单能 X 射线吸收法也得到了发展，但在测量中央骨骼 BMD 方面存在局限性。20 世纪 80 年代中期，双能 X 射线吸收法（DXA）问世并得到广泛应用，可用于早期发现、治疗和随访骨质疏松症。它之所以如此受欢迎，有几个原因。DXA 可以在比 DPA 短得多的时间内测量前后脊柱和臀部的 BMD，同时还可以测量外周骨骼的 BMD。其他优点包括对患者的辐射剂量非常低、图像分辨率高、仪器精度高且校准稳定。近年来，DXA 还被应用于侧位脊柱的小梁骨密度、全身的总体骨密度和身体成分以及脊柱的椎体骨折评估。然而，前后位脊柱和髋关节扫描仍然是 DXA 最常见的应用，因为设备中编译并提供了不同年龄、性别和种族人群骨骼部位 BMD 的正常范围数据，这使医生能够立即进行诊断。
