11C-Hydroxyephedrine PET/CT for preoperative surgical planning in large pheochromocytoma and paraganglioma.

Early detection of metastases and timely surgical intervention play a crucial role in the management of neuroendocrine tumors. In large-sized pheochromocytomas and sympathetic paragangliomas (PPGL), functional imaging with positron emission tomography (PET) is recommended, as it improves the detection of metastases, which may go undetected on conventional radiologic imaging. 11C-hydroxyephedrine binds to the norepinephrine transporter receptor and is detected by PET/CT (HED-PET/CT). It has previously demonstrated high accuracy in detecting primary and metastatic PPGL; however, its impact on preoperative staging is unclear. In this study, we retrospectively analyzed a selected cohort of 44 patients with large PPGL to evaluate whether HED-PET/CT influences preoperative clinical decision-making. All patients who underwent HED-PET/CT at Uppsala University Hospital between 2004 and 2024 were screened for inclusion. In total, 44 patients with pheochromocytomas >5 cm and paragangliomas >4 cm were included. HED-PET/CT results were compared with CT/MR findings, and a final consensus was reached on whether preoperative HED-PET/CT would have altered clinical decision-making. HED-PET/CT identified previously undetected metastatic disease in three patients (6.8%), which had not been visualized on CT/MR. Additionally, two patients had discordant findings, where HED-PET/CT revealed additional metastases. In one case, a liver metastasis was identified postoperatively with HED-PET/CT, leading to a metastasectomy that could have potentially been avoided. These findings suggest that HED-PET/CT is highly accurate in detecting metastases; however, its routine preoperative use may be limited and appears to provide significant clinical benefit only in selected patients.