Which radiotracer is commonly used in bone scintigraphy?

Which radiotracer is commonly used in bone scintigraphy?

• A. Iodine-123
• B. Thallium-201
• C. Technetium-99m
• D. Fluorine-18 fluorodeoxyglucose

Answer: (C)

In bone scintigraphy the tracer needs to localize in bone in areas of increased osteoblastic activity and blood flow. Technetium-99m labeled diphosphonates (such as Tc-99m MDP) fit this need perfectly. After injection, these compounds circulate and are taken up by bone along hydroxyapatite crystals, with uptake rising where bone turnover is high. The physical properties of Tc-99m are ideal for imaging: it emits gamma photons at an energy that gamma cameras detect well, has a practical 6-hour half-life, and gives a high bone-to-background signal. This makes it excellent for whole-body surveys to detect metastases, fractures, or infections. The other tracers serve different purposes: iodine-123 targets thyroid tissue, thallium-201 is used mainly for myocardial imaging (and some tumor studies), and fluorine-18 fluorodeoxyglucose is a PET tracer that highlights metabolic activity rather than specifically bone turnover.

In bone scintigraphy the tracer needs to localize in bone in areas of increased osteoblastic activity and blood flow. Technetium-99m labeled diphosphonates (such as Tc-99m MDP) fit this need perfectly. After injection, these compounds circulate and are taken up by bone along hydroxyapatite crystals, with uptake rising where bone turnover is high. The physical properties of Tc-99m are ideal for imaging: it emits gamma photons at an energy that gamma cameras detect well, has a practical 6-hour half-life, and gives a high bone-to-background signal. This makes it excellent for whole-body surveys to detect metastases, fractures, or infections.

The other tracers serve different purposes: iodine-123 targets thyroid tissue, thallium-201 is used mainly for myocardial imaging (and some tumor studies), and fluorine-18 fluorodeoxyglucose is a PET tracer that highlights metabolic activity rather than specifically bone turnover.