Which nuclear medicine test determines if a thyroid mass is hot or cold?

Which nuclear medicine test determines if a thyroid mass is hot or cold?

• A. Scintigraphy
• B. SPECT
• C. PET
• D. CT

Answer: (A)

Thyroid scintigraphy uses a radionuclide tracer to assess how different parts of the thyroid take up activity. After injecting a gamma-emitting tracer such as technetium-99m pertechnetate or iodine-131, the scan shows whether a nodule concentrates more tracer than surrounding tissue. A hot nodule, being hyperfunctioning, takes up more tracer and appears brighter on the scan, while a cold nodule takes up little tracer and appears darker. This functional information is exactly what distinguishes a hot from a cold nodule. SPECT can provide 3D localization when combined with scintigraphy, but the basic test for hot versus cold is the thyroid scintigraphy scan. CT is purely anatomical, and PET is not typically used for this specific functional distinction in thyroid nodules.

Thyroid scintigraphy uses a radionuclide tracer to assess how different parts of the thyroid take up activity. After injecting a gamma-emitting tracer such as technetium-99m pertechnetate or iodine-131, the scan shows whether a nodule concentrates more tracer than surrounding tissue. A hot nodule, being hyperfunctioning, takes up more tracer and appears brighter on the scan, while a cold nodule takes up little tracer and appears darker. This functional information is exactly what distinguishes a hot from a cold nodule. SPECT can provide 3D localization when combined with scintigraphy, but the basic test for hot versus cold is the thyroid scintigraphy scan. CT is purely anatomical, and PET is not typically used for this specific functional distinction in thyroid nodules.