18F-Fluorocholine PET and Multiphase CT Integrated in Dual Modality PET/4D-CT for Preoperative Evaluation of Primary Hyperparathyroidism

The present retrospective study evaluates the diagnostic value of integrated 18F-Fluorocholine positron emission tomography/four-dimensional contrast-enhanced computed tomography (18F-FCH PET/4D-CT) as second-line imaging in preoperative work-up of primary hyperparathyroidism (pHPT), and compares 18F-FCH PET with 4D-CT. Patients with pHPT and negative/discordant first-line imaging addressed for integrated 18F-FCH PET/4D-CT were retrospectively selected. Sensitivity and detection rate (DR%) of 18F-FCH PET/CT, 4D-CT, and PET/4D-CT were calculated according to the per patient and per lesion analyses, and afterwards compared. Histology associated with a decrease more than 50% of perioperative parathyroid hormone (PTH) blood level was used as a gold standard. Persistent high serum PTH and calcium levels during a 6-month follow-up was considered as presence of pHPT in both operated and non-operated patients. 50 patients (55 glands) were included. 44/50 patients (88%) were surgically treated. On a per patient analysis, sensitivity was 93%, 80%, and 95%, and DR% was 82%, 68%, and 84%, respectively for PET/CT, 4D-CT, and PET/4D-CT. PET/CT was more sensitive than 4D-CT (p = 0.046). PET/4D-CT performed better than 4D-CT (p = 0.013) but was equivalent to PET/CT alone. On a per gland analysis, sensitivity PET/CT, 4D-CT, and PET/4D-CT was 88%, 66%, and 92%, and DR% was 79%, 57%, and 83%, respectively. PET/CT and PET/4D-CT were more sensitive than 4D-CT alone (p = 0.01, p < 0.001, respectively). However, PET/CT and PET/4D-CT performed similarly. In conclusion, 18F-FCH PET provides better identification of hyperfunctioning parathyroids than 4D-CT and the combination of both did not significantly improve diagnostic sensitivity. Further investigations involving larger populations are necessary to define the role of 18F-FCH PET/4D-CT as a “one-stop shop” second-line imaging in preoperative work-up of pHPT, especially considering the additional patient radiation exposure due to multi-phase CT.