131 I Accumulation Due to an Intrauterine Device in a Papillary Thyroid Carcinoma Patient.

A 46-year-old woman underwent 131 I radiotherapy following thyroidectomy for papillary thyroid carcinoma. Posttherapeutic 131 I scintigraphy was performed 4 days later. Both attenuation-corrected and non-attenuation-corrected 131 I tomography images elucidated an intrauterine device with avid 131 I uptake in her uterus. This case illustrated that an intrauterine device should be considered as a potential cause of false-positive results in posttherapeutic 131 I scintigraphy, highlighting the need for accurate image interpretation to avoid unnecessary treatment.