What is the role of thyroid scintigraphy in the workup of papillary thyroid carcinoma (PTC)?

Updated: Jun 18, 2020
  • Author: Ponnandai S Somasundar, MD, MPH, FACS; Chief Editor: Neetu Radhakrishnan, MD  more...
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Answer

Before the advent of fine-needle aspiration biopsy (FNAB), thyroid scintigraphy (or thyroid scanning) performed with technetium Tc 99m pertechnetate (99mTc) or radioactive iodine (I131 or I123) was the initial diagnostic procedure of choice for a thyroid evaluation. The procedure is not as sensitive or specific as FNAB for distinguishing benign nodules from malignant nodules. Iodine-containing compounds and seafood interfere with any tests using radioactive iodine.

Scintigraphic images of the thyroid are acquired 20-40 minutes after intravenous administration of the radionuclide. In more than 90% of cases, clearly benign nodules appear as hot nodules because they are hyperfunctioning and have a high captation rate of radionuclide and, physiologically, of iodine. Malignant nodules usually appear as cold because they are not functioning.

Findings from thyroid scanning are helpful and specific in the preoperative and immediate postoperative periods for localization of cancer or residual thyroid tissue and in observing for tumor recurrence or metastasis. Thyroid scanning can also be useful for diagnosing benign lesions (by FNAB) or solid lesions (by ultrasound).


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