Innovative approaches to noninvasive bone densitometry

In conclusion, this review has endeavored to familiarize the practicing radiologist with some of the newer approaches to noninvasive bone densitometry that are currently being explored as potential improvements over existing techniques. Three-dimensional volumetric CT is a practical means of measuring bone density in the proximal femur, owing to the widespread availability of the necessary scanning equipment, and affords enhanced prediction of biomechanical parameters in the spine and hip, but suffers from limitations similar to those of conventional quantitative CT. Dual-energy projection radiography offers significant potential advantages over dual-photon absorptiometry from the standpoint of precision, radiation dose, image quality, and examination time, but remains to be thoroughly tested. Compton scattering appears to be a viable alternative to single-photon absorptiometry for bone density determinations in the peripheral skeleton. Neutron and proton activation analysis are unlikely to achieve widespread application, owing to their cyclotron-dependent nature, although the former will probably remain the optimal means for determining total body calcium. Experience with scanning-slit fluorography and magnetic resonance as applied to noninvasive bone densitometry is currently too limited to permit prediction of their ultimate role in this respect. As a final point, it should be noted that major incentives for mobilization of bone densitometric equipment currently exist: on Earth, as a means of facilitating patient access and saving money via joint ventures, and in space for monitoring the adverse effects of weightlessness on skeletal mass and the ability to function following return to a gravity environment.