Functional Imaging Signature of Patients Presenting with Polycythemia/Paraganglioma Syndromes

Pheochromocytoma/paraganglioma (PPGL) syndromes associated with polycythemia have previously been described in association with mutations in the von Hippel-Lindau gene. Recently, mutations in the prolyl hydroxylase gene (PHD) 1 and 2 and in the hypoxiainducible factor 2 alpha (HIF2A) were also found to be associated with multiple and recurrent PPGL. Such patients also presented with PPGL and polycythemia, and later on, some presented with duodenal somatostatinoma. In additional patients presenting with PPGL and polycythemia, no further mutations have been discovered. Because the functional imaging signature of patients with PPGLpolycythemia syndromes is still unknown, and because these tumors (in most patients) are multiple, recurrent, and metastatic, the goal of our study was to assess the optimal imaging approach using 4 different PET radiopharmaceuticals and CT/MRI in these patients. Methods: Fourteen patients (10 women, 4 men) with confirmed PPGL and polycythemia prospectively underwent Ga-68-DOTATATE (13 patients), F-18-FDG (13 patients), F-18-fluorodihydroxyphenylalanine (F-18-FDOPA) (14 patients), F-18-fluorodopamine (F-18-FDA) (11 patients), and CT/MRI (14 patients). Detection rates of PPGL lesions were compared between all imaging studies and stratified between the underlying mutations. Results: F-18-FDOPA and F-18-FDA PET/CT showed similar combined lesion-based detection rates of 98.7% (95% confidence interval [CI], 92.7%-99.8%) and 98.3% (95% CI, 90.9%-99.7%), respectively. The detection rates for Ga-68-DOTATATE (35.3%; 95% CI, 25.0%-47.2%), F-18-FDG (42.3; 95% CI, 29.9%-55.8%), and CT/MRI (60.3%; 95% CI, 48.8%-70.7%) were significantly lower (P < 0.01), irrespective of the mutation status. Conclusion: F-18-FDOPA and F-18-FDA are superior to F-18-FDG, Ga-68-DOTATATE, and CT/MRI and should be the radiopharmaceuticals of choice in this rare group of patients.