Use of MIBG scanning in the diagnostic pathway for phaeochromocytoma and paragangliomas; experience of a uk tertiary centre

Zen Lim; Hafsa Tahir; Rebecca Sagar; Jong Mechteld De; Afroze Abbas

doi:10.1530/endoabs.109.P26

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Endocrine Abstracts (2025) 109 P26 | DOI: 10.1530/endoabs.109.P26

SFEBES2025 Poster Presentations Adrenal and Cardiovascular (61 abstracts)

Use of MIBG scanning in the diagnostic pathway for phaeochromocytoma and paragangliomas; experience of a uk tertiary centre

Zen Lim ¹ , Hafsa Tahir ¹ , Rebecca Sagar ² , Mechteld De Jong ² & Afroze Abbas ²

Author affiliations

¹University of Leeds, School of Medicine, Leeds, United Kingdom; ²Leeds Regional Adrenal Tumour Service, Leeds Teaching Hospitals NHS Trust, Leeds, United Kingdom

Background: Phaeochromocytomas and paragangliomas (PPGLs) are often identified incidentally, with a high proportion being asymptomatic. Screening, typically with unenhanced CT scan, and biochemistry is often inconclusive. Therefore, many patients have additional I-123 metaiodobenzylguanidine scintigraphy (MIBG) which may help with diagnosis and staging. Sensitivity/specificity of MIBG in PPGLs vary depending on lesion characteristics and genetics. This study aimed to evaluate the role of MIBG in PPGL management in a large UK cohort.

Method: Retrospective data were collected on patients with probable PPGLs at Leeds Teaching Hospitals between 2018-2023. Data collected included demographics, lesion properties, screening biochemistry +/- MIBG and histological diagnosis.

Results: Of 99 patients (56.6% male), 90 (91.8%) had secretory biochemistry. 73 (91.2%) of those with available histology were consistent with PPGl. 72 (72.7%) underwent an MIBG scan. Patients who did not have MIBG scans tended to have larger lesions (mean 4.9 cm versus 3.7 cm). 66 (91.7%) of MIBG scans showed avidity. Of those with secretory biochemistry, 68 (75.6%) had MIBG, 63 of these (92.6%) showed avidity. Management changed as a result in only 3 cases. In the non-avid group, 4 (80.0%) were PPGL histologically. In 8 patients with non-secretory biochemistry, 4 (50.0%) had MIBG and 3 of these showed avidity. One case although MIBG-avid, histologically was not a PPGl. One case was a non-avid, non-secretory PPGl. Of 6 patients within the whole cohort who had non-avidity on MIBG, 3 had further imaging.

Conclusion: Use of MIBG in initial characterisation of PPGLs in patients with secretory biochemistry does not appear to alter diagnosis or management in the vast majority of cases. In patients with non-secretory biochemistry but radiological suspicion of PPGL, MIBG was useful in guiding diagnosis in 75% of cases. These data suggest that MIBG use should be targeted to patients with diagnostic uncertainty, particularly in those with non-secretory biochemistry.