Table 1. Summary of indications for different tracers in thyroid nodules according to current guidelines.

Tracer	Indication
Iodine-123	Indicated in clinically or incidentally discovered thyroid nodule if the serum TSH is subnormal (2)
Technetium-99m-pertechnetate	Indicated in clinically or incidentally discovered thyroid nodule if the serum TSH is subnormal and if iodine-123 is not available (2)
Technetium-99m-MIBI	No recommendation according to current guidelines. It can be used in cold nodules (based on iodine-123 or technetium-99m-pertechnetate scintigraphy) (23-25,29)
Fluorine-18-FDG	Fluorine-18-FDG is not routinely recommended for the evaluation of thyroid nodules with indeterminate cytology (2)