F-18-FDOPA PET/CT Imaging of MAX-Related Pheochromocytoma
Résumé
Context: MYC-associated factor X (MAX) has been recently described as a new susceptibility pheochromocytoma (PHEO) gene with a total of similar to 40 reported cases. At present, no study has specifically described the functional imaging phenotype of MAX-related PHEO. Objective, Patients, and Design: The objective of the present study was to present our experience with contrast-enhanced computed tomography (CT) and F-18-fluorodihydroxyphenylalanine (F-18-FDOPA) positron emission tomography (PET)/CT in six consecutive patients (four at the initial diagnosis and two at the follow-up evaluation) with rare, but clinically important, MAX-related PHEOs. In five patients, F-18-FDOPA was also compared with other radiopharmaceutical agents. Results: The patients had five different mutations in the MAX gene that caused disruption of Max/Myc interaction and/or abolished interaction with DNA based on in silico analyses. All but one patient developed bilateral PHEOs during their lifetime. In all cases, F-18-FDOPA PET/CT accurately visualized PHEOs that were often multiple within the same gland or bilaterally and detected more adrenal and extra-adrenal lesions than did CT (per-lesion sensitivity, 90.9% vs 52.4% for CT/magnetic resonance imaging). The two PHEOs missed on F-18-FDOPA PET/CT were,1 cm, corresponding to nodular adrenomedullary hyperplasia. Ga-68-DOTA, Tyr3-octreotate PET/CT detected fewer lesions than did F-18-FDOPA PET/CT in one of three patients, and F-18-fluorodeoxyglucose PET/CT was only faintly positive in two of four patients with underestimation of extra-adrenal lesions in one patient. Conclusions: MAX-related PHEOs exhibit a marked F-18-FDOPA uptake, a finding that illustrates the common well-differentiated chromaffin pattern of PHEOs associated with activation of kinase signaling pathways. F-18-FDOPA PET/CT should be considered as the first-line functional imaging modality for diagnostic or follow-up evaluations for these patients.