Table 8.

Additional bone densitometry technologies

CT-based absorptiometry: Quantitative computed tomography (QCT) measures volumetric integral, trabecular, and cortical bone density at the spine and hip and can be used to determine bone strength, whereas pQCT measures the same at the forearm or tibia. High-resolution pQCT (HR-pQCT) at the radius and tibia provides measures of volumetric density, bone structure, and microarchitecture. In postmenopausal women, QCT measurement of spine trabecular BMD can predict vertebral fractures, whereas pQCT of the forearm at the ultradistal radius predicts hip but not vertebral fractures. There is insufficient evidence for fracture prediction in men. QCT and pQCT are associated with greater amounts of radiation exposure than central DXA or pDXA.

Trabecular Bone Score (TBS) is an FDA-approved technique which is available on some densitometers. It may measure the microarchitectural structure of bone tissue and may improve the ability to predict the risk of fracture.

The following technologies are often used for community-based screening programs because of the portability of the equipment. Results are not equivalent to DXA and abnormal results should be confirmed by physical examination, risk assessment, and central DXA.

Peripheral dual-energy x-ray absorptiometry (pDXA) measures areal bone density of the forearm, finger, or heel. Measurement by validated pDXA devices can be used to assess vertebral and overall fracture risk in postmenopausal women. There is insufficient evidence for fracture prediction in men. pDXA is associated with exposure to trivial amounts of radiation. pDXA is not appropriate for monitoring BMD after treatment.

Quantitative ultrasound densitometry (QUS) does not measure BMD directly but rather speed of sound (SOS) and/or broadband ultrasound attenuation (BUA) at the heel, tibia, patella, and other peripheral skeletal sites. A composite parameter using SOS and BUA may be used clinically. Validated heel QUS devices predict fractures in postmenopausal women (vertebral, hip, and overall fracture risk) and in men 65 and older (hip and nonvertebral fractures). QUS is not associated with any radiation exposure.