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

Abstract

Preoperative molecular imaging is paramount to direct surgery in primary hyperparathyroidism (pHPT). We investigated the diagnostic performance of 18F-fluorocholine (18F-FCH) PET/CT compared with 11C-methionine (11C-MET) PET/CT for localization of hyperfunctioning parathyroid tissue in patients with pHPT and negative or inconclusive 99mTc-sestaMIBI (99mTc-MIBI) SPECT findings. Methods: Fifty-eight patients with biochemical evidence of pHPT and negative or inconclusive 99mTc-MIBI SPECT findings were referred for presurgical detection and localization of hyperfunctioning parathyroid tissue by 11C-MET and 18F-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. 18F-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 11C-MET PET/CT. 18F-FCH localized 11 additional foci (6 positive and 5 inconclusive), compared with 11C-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 followup, 21 patients (81%) were considered cured after surgery, whereas 3 patients (12%) had persistence of hypercalcemia. With inconclusive cases being considered negative, 18F-FCH PET/CT correctly localized 26 lesions in 24 of 26 patients (92%), comparedwith 16 lesions in 15 of 26 patients (58%) localized by 11C-MET PET/CT. Per-patient-based sensitivity and positive predictive value were 96% and 96%, respectively, for 18F-FCH and 60% and 94%, respectively, for 11C-MET (P < 0.0001). Per-lesion-based sensitivity and positive predictive value were 84% and 90%, respectively, for 18F-FCH and 52% and 94%, respectively, for 11C-MET (P < 0.0001). Conclusion: In the presence of biochemical evidence of pHPT with negative or inconclusive 99mTc-MIBI SPECT findings, 18F-FCH PET/CT performs better than 11C-MET PET/ CT for the detection of pathologic parathyroid tissue, allowing localization of parathyroid adenoma or hyperplasia in 96%of patients.