Densitometriaa

Densitometry, in the medical context, refers to the measurement of tissue density with imaging techniques, most notably bone mineral density (BMD). Bone densitometry is used to diagnose osteoporosis, assess fracture risk, and monitor responses to treatment. It can also be applied to estimate density in other tissues or to evaluate body composition with some devices.

The most widely used method is dual-energy X-ray absorptiometry (DXA), which provides areal BMD measurements at sites such as the lumbar spine and hip, and is also used for peripheral sites like the forearm or heel. Other approaches include quantitative computed tomography (QCT), which yields volumetric BMD, and quantitative ultrasound (QUS), which estimates bone properties at peripheral sites without using X-ray dose. Some densitometry assessments are used for research or specialized clinical purposes, including measurements of non-bone tissues or body composition.

Interpretation relies on reference values. A T-score compares an individual’s BMD with that of a young healthy reference population, while a Z-score compares with an age- and sex-matched population. Osteoporosis is defined by a T-score of -2.5 or lower; osteopenia falls between -1.0 and -2.5. In children and adolescents, Z-scores are emphasized. Fracture risk can be further refined by incorporating clinical risk factors, sometimes via tools like FRAX alongside DXA results.

Procedure considerations include the technique’s low radiation exposure, rapid and noninvasive nature, and the influence of artifacts such as degenerative changes, vascular calcifications, obesity, or scoliosis on measurement accuracy. Regular quality control and site-specific reference databases are essential for reliable reporting.