# 11C‐Hydroxyephedrine PET/CT for preoperative surgical planning in large pheochromocytoma and paraganglioma

## TL;DR

This study evaluates the use of 11C-hydroxyephedrine PET/CT in preoperative planning for large pheochromocytoma and paraganglioma, finding it detects metastases missed by conventional imaging.

## Contribution

The study provides new evidence on the clinical utility of HED-PET/CT in preoperative staging of large PPGL tumors.

## Key findings

- HED-PET/CT identified metastatic disease in 3 out of 44 patients not detected by CT/MR.
- Two patients had additional metastases revealed by HED-PET/CT.
- In one case, HED-PET/CT detected a liver metastasis post-surgery, potentially avoiding unnecessary surgery.

## Abstract

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.