99mTc Sodium Pertechnetate Uptake in Ectopic Mediastinal Thyroid Tissue on Hybrid Thyroid Scintigraphy

Ectopic thyroid is a rare/incidental imaging finding. When discovered, 90% of ectopic thyroid is found typically along the pathway of embryologic migration of thyroid tissue, whereas around 10% have been discovered in other anatomical locations including the mediastinum and the heart. Thyroid scintigraphy with Tc-99m sodium pertechnetate (TcO4) is peculiar for thyroid tissue uptake. The current case, clinically euthyroid, had heterogeneous uptake in multinodular goiter with uptake in the ectopic thyroid tissue in right paratracheal location on functional imaging with TcO4. Subsequent single photon emission computed tomography/computed tomography (SPECT/CT) imaging confirmed the ectopic thyroid tissue.