What is the purpose of a bone scan in nuclear medicine?

• A. Detects areas of increased osteoblastic activity such as fractures, infections, or metastases.
• B. Measures cardiomyocyte metabolism.
• C. Images soft tissues of the limbs exclusively.
• D. Directly visualizes bone mineral density.

Answer: (A)

A bone scan uses a radiotracer that localizes to bone where osteoblasts are active, so it highlights areas of increased bone turnover. When the tracer (often technetium-99m–labeled phosphate) is taken up at sites of new or ongoing bone formation, those regions appear as hot spots on the scan. This makes the test especially good for detecting fractures (including occult or healing fractures), infections like osteomyelitis, and metastases, as these conditions trigger higher osteoblastic activity and thus greater tracer uptake. The scan is very sensitive for bone metabolism and can reveal issues before structural changes are visible on X-rays.

It doesn’t measure cardiomyocyte metabolism—that would involve cardiac-specific metabolic imaging. It isn’t limited to soft tissues, though soft-tissue uptake can occur, and its primary purpose isn’t to image soft tissues exclusively. It also doesn’t directly visualize bone mineral density—that’s what DEXA scans are for.