68 Ga-FAPI PET/MR for Active Thyroid Eye Disease Following Thyroidectomy: A Case Supporting Its Dual Role in Clinical Management.

A 30-year-old man experienced ocular motility impairment and exophthalmos immediately after a total thyroidectomy for papillary thyroid carcinoma at an external hospital. Two months later, 131 I therapy exacerbated his ocular symptoms. He presented to our ophthalmology department for evaluation, where a 68 Ga-FAPI PET/MR scan revealed active thyroid eye disease (TED) and residual tumor lesions. Based on these findings and clinical evaluation, a multidisciplinary team formulated and implemented an effective treatment plan. This case highlights the dual role of 68 Ga-FAPI PET/MR in assessing TED activity and postoperative tumor status, providing critical insights for managing TED in the context of recent thyroidectomy.