Accessory Thyroid Tissue Detected Using 131 I SPECT/CT Imaging.

Thyroid ectopia has been described as a rare congenital anomaly, characterized by the presence of a thyroid gland in locations other than the orthotopic pretracheal location. The prevalence of accessory thyroid tissue in patients undergoing postablative radioiodine therapy in a 12-month period at a tertiary hospital nuclear medicine department was assessed. Fifty-seven patients were treated between September 2020 and September 2021. Retrospective analysis identified the presence and location of all accessory thyroid tissue separate from the orthotopic pretracheal thyroid gland. Accessory thyroid tissue was present in 21.1% (12/57) of the patients. Accessory thyroid tissue was most commonly located in the lingual region.