What is the role of a thyroid sestamibi scan in detecting or to rule out thyroid malignancy?

Parathyroid: Sestamibi is more often used to evaluate the parathyroid glands for possible parathyroid adenoma. They cannot rule out thyroid malignancy. If you have questions, see an endocrinologist. You may need a biopsy if you have a questionable thyroid mass.

May prevent surgery: More commonly used for parathyroid scan. If a thyroid nodule is indeterminate on biopsy, the test may be useful. If the nodule does not take up the sestamibi radiotracer, it is very likely benign and the scan may prevent an unnecessary surgery. If the nodule lights up with the scan, this can help with decision making regarding possible surgery.

Not for thyroid CA: Sestamibi scans are not indicated for thyroid cancer evaluation. It will very rarely reveal a thyroid cancer. It would only be indicated if your doctor suspected a very rare neuroendocrine tumor or a parathyroid tumor (after checking calcium and PTH and confirming they are both elevated).

No role: Sestamibi scanning is for HYPERparathyroidism. NOT thyroid nodule diagnosis. Iodine scanning used to be done for this but is no longer valid for that purpose. The most direct path to thyroid nodule diagnosis is ultrasound with fine needle aspiration. Incidental cancers of the breasts, lymph nodes, etc. have been diagnosed by sestamibi.