MON-755 C11 Choline-PET/CT Is A Localization Standard For Re-operative Parathyroidectomy In Primary Hyperparathyroidism

Abstract Disclosure: P. Hopmann: None. S. Lund: None. T. Foster: None. B. Dy: None. T. McKenzie: None. G. Johnson: None. R.A. Wermers: None. M. Lyden: None. Background: Previous studies have demonstrated that C11 choline positron emission tomography/computed tomography (Choline-PET/CT) can localize abnormal parathyroid glands in the re-operative setting. This study assesses a large volume of patients with primary hyperparathyroidism (1HPT) who underwent Choline-PET/CT to confirm its utility in the setting of negative or equivocal conventional imaging. Methods: All patients who underwent Choline-PET/CT for evaluation of 1HPT from July 2017 to July 2024 at a single institution were reviewed. Inclusion criteria were patients who underwent parathyroidectomy and had lab testing to assess for cure (defined as >50% drop from baseline PTH and into normal range, or resolution of hypercalcemia at follow-up). Sensitivity, positive predictive value (PPV), false negative rate (FNR), and accuracy were compared to conventional imaging (neck ultrasound, parathyroid scan, and parathyroid four-dimensional CT (4D-CT)). Subgroup analysis was conducted comparing sensitivity of modalities among index operations, and separately in re-operations. Results: 176 patients were identified. 85 underwent parathyroidectomy, 1 patient was excluded due to lacking data to evaluate for cure. Of 91 patients who did not undergo parathyroidectomy, 45 were non-localizing on all imaging, and 46 had positive Choline-PET/CT findings but opted against surgery due to mild disease or prohibitive re-operative risk. Of the included 84 parathyroidectomy patients, 61 failed to localize on at least one conventional modality, and 15 failed to localize on all conventional studies. 67 patients (80%) achieved cure, of whom 53 were re-operations (range of 1-4 prior operations, average 1.5). Choline-PET/CT outperformed conventional modalities across sensitivity, PPV, FNR, and accuracy. Among index operations, Choline-PET/CT had significantly higher sensitivity than conventional modalities (100% vs 27% for ultrasound, 30% for parathyroid scan, 29% for 4D-CT; p values ≤0.01). This was also true in re-operations (95% for Choline-PET/CT vs 13% for ultrasound, 30% for parathyroid scan, 32% for 4D-CT; p values <0.01). Conclusion: C11 choline-PET/CT is a valuable imaging modality in the re-operative setting and demonstrates utility for index operations. It provides localization when other modalities fail and allows for a high surgical cure rate. Further investigation into its utility as a primary imaging modality is warranted. Presentation: Monday, July 14, 2025