MEN1 and glycogen storage disease VI: Several studies have proposed preoperative localization procedures that are more sensitive to detect multiglandular disease, small lesions, or possible ectopic parathyroid tissue in MEN1-related PHPT, such as 18F-fluorocholine PET/CT (FCH-PET/CT), with or without enhanced arterial imaging, and four-dimensional computed tomography (4D-CT), especially when conventional preoperative imaging before the first intervention is inconclusive [19,20,21,22].