Which statement accurately describes DEXA?

Which statement accurately describes DEXA?

• A. It requires intravenous contrast containing iodine.
• B. It is noninvasive and uses no iodine-containing dyes.
• C. It always requires fasting prior to the test.
• D. It measures bone density using ultrasound.

Answer: (B)

DEXA measures bone mineral density using dual-energy X-ray absorptiometry, a noninvasive test that uses no iodine-containing dyes. It sends low-dose X-ray beams at two energies to distinguish bone from soft tissue, allowing accurate density measurements at sites like the spine and hip. Because no contrast is needed and no fasting is required, it’s a quick, routine screening tool for osteoporosis risk with very low radiation exposure. The statements about intravenous iodine contrast and fasting are inaccurate because DEXA doesn’t use dyes or require fasting, and the statement about ultrasound is incorrect because DEXA relies on X-ray attenuation, not ultrasound.

DEXA measures bone mineral density using dual-energy X-ray absorptiometry, a noninvasive test that uses no iodine-containing dyes. It sends low-dose X-ray beams at two energies to distinguish bone from soft tissue, allowing accurate density measurements at sites like the spine and hip. Because no contrast is needed and no fasting is required, it’s a quick, routine screening tool for osteoporosis risk with very low radiation exposure. The statements about intravenous iodine contrast and fasting are inaccurate because DEXA doesn’t use dyes or require fasting, and the statement about ultrasound is incorrect because DEXA relies on X-ray attenuation, not ultrasound.