Challenging pre-surgical localization of hyperfunctioning parathyroid glands in primary hyperparathyroidism: the added value of ¹⁸F-Fluorocholine PET/CT

Purpose: To evaluate the added value of ¹⁸F-Fluorocholine (¹⁸F-FCH) PET/CT in presurgical imaging of patients with primary hyperparathyroidism (HPT) and challenging localization of the hyper-functioning parathyroid glands. Methods: We included 27 consecutive patients with primary HPT (19 F; median age: 58 years), with either (i) non-conclusive pre-surgical localization with ⁹⁹mTc-sestaMIBI scintigraphy and neck ultrasonography (US), (ii) recurrence of previously operated HPT, or (iii) familiar HPT with a suspicion of multiple gland disease. Histological findings and resolution of HPT were considered as the gold standard. Results: ¹⁸F-FCH PET/CT was positive in 24/27 patients. Twenty-one patients underwent surgery with 27 resected lesions (14 adenomas, 11 hyperplastic glands, two hyper-functioning histologically normal glands), with resolution of HPT in 19/21 patients (90%). ¹⁸F-FCH PET/CT localized 22 lesions in 17/21 patients (per patient: sensitivity 81%, positive predictive value (PPV) 94%; per gland: sensitivity 76%, PPV 85%, specificity 91%, negative predictive value (NPV) 86%). ¹⁸F-FCH PET/CT found eight lesions which were undetectable on both ⁹⁹mTc-sestaMIBI scintigraphy and US. In patients with a familial HPT and/or a multiple gland disease, sensitivity was 100 and 79% on a per-patient and a per-gland analysis respectively, while NPV was 63%. In six patients with a persistence or recurrence of previously treated HPT, ¹⁸F-FCH PET/CT localized all lesions, both in sporadic and familiar disease. Conclusions: ¹⁸F-FCH PET/CT is a promising modality in challenging pre-surgical localization of hyper-functioning parathyroid glands, such as inconclusive standard imaging, recurrence after surgery, or suspected multiple gland disease.