Head-to-head comparison of [11C]methionine PET, [11C]choline PET, and 4-dimensional CT as second-line scans for detection of parathyroid adenomas in primary hyperparathyroidism

Purpose Accurate preoperative localization is imperative to guide surgery in primary hyperparathyroidism (pHPT). It remains unclear which second-line imaging technique is most effective after negative first-line imaging. In this study, we compare the diagnostic effectiveness of [ 11 C]methionine PET/CT, [ 11 C]choline PET/CT, and four dimensional (4D)-CT head-to-head in patients with pHPT, to explore which of these imaging techniques to use as a second-line scan. Methods We conducted a powered, prospective, blinded cohort study in patients with biochemically proven pHPT and prior negative or discordant first-line imaging consisting of ultrasonography and 99m Tc-sestamibi. All patients underwent [ 11 C]methionine PET/CT, [ 11 C]choline PET/CT, and 4D-CT. At first, all scans were interpreted by a nuclear medicine physician, and a radiologist who were blinded from patient data and all imaging results. Next, a non-blinded scan reading was performed. The scan results were correlated with surgical and histopathological findings. Serum calcium values at least 6 months after surgery were used as gold standard for curation of HPT. Results A total of 32 patients were included in the study. With blinded evaluation, [ 11 C]choline PET/CT was positive in 28 patients (88%), [ 11 C]methionine PET/CT in 23 (72%), and 4D-CT in 15 patients (47%), respectively. In total, 30 patients have undergone surgery and 32 parathyroid lesions were histologically confirmed as parathyroid adenomas. Based on the blinded evaluation, lesion-based sensitivity of [ 11 C]choline PET/CT, [ 11 C]methionine PET/CT, and 4D-CT was respectively 85%, 67%, and 39%. The sensitivity of [ 11 C]choline PET/CT differed significantly from that of [ 11 C]methionine PET/CT and 4D-CT ( p = 0.031 and p