[18F]Fluorocholine PET/MRI and [18F]Fluorocholine PET/CT as first- and second-line imaging in primary hyperparathyroidism – who takes the lead?

Accurate preoperative localization of hyperfunctioning parathyroid glands is essential for enabling a focused surgical approach in patients with primary hyperparathyroidism (pHPT). Our study aims to determine the diagnostic value of 18F-fluorocholine positron emission tomography/magnetic resonance imaging ([18F]FCH PET/MRI) and [18F]FCH PET/computed tomography (PET/CT) in identifying parathyroid adenomas. We conducted a retrospective study to assess the diagnostic accuracy of [18F]FCH PET/MRI and [18F]FCH PET/CT as first- and second-line methods for detecting parathyroid adenomas in patients with pHPT. The primary endpoints included patient-based sensitivity, specificity, and positive predictive value (PPV), with intraoperative surgical localization and histopathological analysis serving as reference, i.e., gold standard. The study included 322 patients. A total of 264 patients underwent [18F]FCH PET/MRI, thereof 155 and 109 as a second- and first-line method, respectively. [18F]FCH PET/CT was performed in 58 patients, thereof 44 and 14 in a second- and first-line setting, respectively. Total sensitivity, specificity, PPV, negative predictive value (NPV), and diagnostic accuracy of [18F]FCH PET/MRI were 0.967, 0.818, 0.983, 0.692, and 0.955, respectively, while the same parameters for [18F]FCH PET/CT were 0.980, 0.875, 0.980, 0.875, and 0.966, respectively (all p > 0.05). There was also no difference between the two methods in the first- or second-line imaging scenarios. Both [18F]FCH PET/MRI and [18F]FCH PET/CT are highly accurate imaging modalities for localizing parathyroid adenomas in both first- and second-line settings. They can be regarded as “top-scoring” or “one-stop-shop” techniques for preoperative assessment.