A review of the role of functional imaging in the evaluation of pheochromocytoma exemplified in a case of metastatic pheochromocytoma revealed by [18-F]-FDG PET/CT after normal [123-I]-MIBG scintigraphy

1066 Learning Objectives 1. Understand the diagnostic strategy of pheochromocytoma and the role functional imaging modalities play in the initial evaluation and follow up of pheochromocytoma. 2. Discuss the advantages and limitations of the different functional imaging modalities in diagnostic localization of pheochromocytoma. 3. Illustrate the role of [18-F]-FDG PET/CT in identifying metastatic pheochromocytoma by presenting a case of metastatic pheochromocytoma revealed by [18-F]-FDG PET/CT after two normal [123-I]-metaiodobenzylguanidine (MIBG) scintigraphy studies in a patient with biochemical evidence of disease. 4. Discuss the most likely reasons for discordant results between functional imaging modalities in evaluation of pheochromocytoma. Functional imaging plays a vital role in confirming the diagnosis of pheochromocytoma in the presence of biochemical markers of disease and suspicious findings on anatomical imaging (CT/MRI) as well as excluding metastatic disease. To that end it is important to carefully consider each functional imaging modality’s strengths and limitations in determining the most appropriate modality to recommend in any given clinical scenario. We present a case of metastatic pheochromocytoma identified on [18-F]-FDG PET/CT after two normal [123-I]-MIBG scintigraphy studies which exemplifies this point. Discordant results between functional imaging modalities may be due to the unique radioligand receptor of each modality with respect to tumor cell properties. The relative roles of commonly available functional imaging modalities in the evaluation of suspicious adrenal tumors, paragangliomas, and metastatic pheochromocytoma are debated in current literature. This educational exhibit will provide residents, nuclear medicine physicians, and other practitioners with an up to date review of the literature of the advantages and limitations of available functional imaging modalities in the evaluation of pheochromocytoma