When and why

Dual-energy X-ray Absorptiometry (DEXA) technology works by measuring the amount of x-rays that are absorbed by the bones and tissue. Through the use of two x-ray energies an accurate estimation of bone density and tissue type can be made.

The DEXA is one of several imaging procedures widely deployed in contemporary medicine. In particular, it is commonly used in to identify people with thinning bones or osteoporosis.

Antiretroviral therapy is believed to contribute to body fat changes known as lipodystrophy and may contribute to higher than average rates of thinning bones among people with HIV. In the context of HIV infection, DEXA is used to monitor changes in body composition in people taking antiretroviral therapy. When a case definition of lipodystrophy has been established, it may be an important tool in the diagnosis of this condition.

When having a DEXA scan, the scanner will pass over the part of your body being imaged. An energy beam of very low dose x-rays passes through your body. You do not feel anything during the DEXA scan. The x-rays are measured by a detector and an image is then produced.

How it will help

Diagnosis of lipodystrophy may lead to review of antiretroviral therapy, as some drugs have been particularly associated with fat loss. Diagnosis of thinning bones can lead to interventions to prevent further bone deterioration. DEXA scans may also help doctors better understand these conditions in people with HIV infection.