<scp> ¹¹ C </scp> ‐Hydroxyephedrine <scp>PET</scp> / <scp>CT</scp> 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.