18 F-Fluorocholine PET/CT Is More Sensitive Than 11 C-Methionine PET/CT for the Localization of Hyperfunctioning Parathyroid Tissue in Primary Hyperparathyroidism.

Preoperative molecular imaging is paramount to direct surgery in primary hyperparathyroidism (pHPT). We investigated the diagnostic performance of ¹⁸ F-fluorocholine ( ¹⁸ F-FCH) PET/CT compared with ¹¹ C-methionine ( ¹¹ C-MET) PET/CT for localization of hyperfunctioning parathyroid tissue in patients with pHPT and negative or inconclusive ^99m Tc-sestaMIBI ( ^99m Tc-MIBI) SPECT findings. Methods: Fifty-eight patients with biochemical evidence of pHPT and negative or inconclusive ^99m Tc-MIBI SPECT findings were referred for presurgical detection and localization of hyperfunctioning parathyroid tissue by ¹¹ C-MET and ¹⁸ F-FCH PET/CT. The PET/CT results were classified into 3 categories (positive, inconclusive, or negative) based on the nodular aspect of tracer uptake and the visualization of corresponding nodules on CT. The PET/CT results were correlated with the surgical and histopathologic findings, which were used as the gold standard. Results: Fifty-three patients were included for analysis. ¹⁸ F-FCH PET/CT was positive in 39 patients (74%), inconclusive in 5 (9%), and negative in 9 (17%), compared with 25 (47%), 12 (23%), and 16 (30%), respectively, for ¹¹ C-MET PET/CT. ¹⁸ F-FCH localized 11 additional foci (6 positive and 5 inconclusive), compared with ¹¹ C-MET. Twenty-six patients (sex ratio, 10/16 M/F) underwent surgery, with resection of 31 lesions (22 adenomas, 6 hyperplastic glands, and 3 carcinomas) and 1 normal gland. At follow-up, 21 patients (81%) were considered cured after surgery, whereas 3 patients (12%) had persistence of hypercalcemia. With inconclusive cases being considered negative, ¹⁸ F-FCH PET/CT correctly localized 26 lesions in 24 of 26 patients (92%), compared with 16 lesions in 15 of 26 patients (58%) localized by ¹¹ C-MET PET/CT. Per-patient-based sensitivity and positive predictive value were 96% and 96%, respectively, for ¹⁸ F-FCH and 60% and 94%, respectively, for ¹¹ C-MET ( P < 0.0001). Per-lesion-based sensitivity and positive predictive value were 84% and 90%, respectively, for ¹⁸ F-FCH and 52% and 94%, respectively, for ¹¹ C-MET ( P < 0.0001). Conclusion: In the presence of biochemical evidence of pHPT with negative or inconclusive ^99m Tc-MIBI SPECT findings, ¹⁸ F-FCH PET/CT performs better than ¹¹ C-MET PET/CT for the detection of pathologic parathyroid tissue, allowing localization of parathyroid adenoma or hyperplasia in 96% of patients.
(© 2022 by the Society of Nuclear Medicine and Molecular Imaging.)