Role of scintigraphy with tumor-seeking agents in the diagnosis and preoperative staging of malignant thyroid nodules.

The commonly used procedure for the diagnosis of thyroid nodule malignancy is based on high resolution thyroid ultrasonography (US) combined with US-guided fine needle aspiration cytology (FNAC). The other imaging procedures have a limited role in malignancy diagnosis. However, nuclear medicine procedures, particularly scintigraphy with tumor-seeking agents such as 201-thallium (201-TI), 99mTc-methoxy-isobutyl-isonitrile (99mTc-MIBI) and 99mTc-tetrofosmin may play an important role in the differential diagnosis between benign and malignant thyroid nodules in cases of non-diagnostic or inadequate FNAC. This type of scintigraphy can also be used in the follow-up of patients with cytologically 'high'-risk thyroid nodules such as Hurtle cell adenomas and follicular adenomas. Furthermore, scans with tumor-seeking agents can be helpful in determining the preoperative staging of thyroid carcinoma patients with locally advanced disease, and in accurately evaluating the extent, and consequently, the surgical management of the disease.