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La PET con 18F-fluoro-L-dihidroxifenilalanina (18F-DOPA) ofrece alta sensibilidad y especificidad en el diagnóstico del paraganglioma extraadrenal no maligno (PGL) y el feocromocitoma (FEO), pero menor sensibilidad en la enfermedad metastásica. Estos tumores son de origen neuroendocrino y pueden detectarse mediante PET con 68Ga-DOTA-Tyr3-octreótido (68Ga-DOTA-TOC). Por tanto, comparamos 68Ga-DOTA-TOC y 18F-DOPA como radiotrazadores para PET/TC para el diagnóstico de PGL extradrenal metastásico y FEO. Las imágenes tomográficas anatómicas y funcionales fusionadas se utilizaron como estándar de referencia.

El feocromocitoma es poco frecuente, y se enmarca en el grupo de los tumores neuroendocrinos. Dichos tumores pueden encontrarse en cualquier parte, desde el cuello a la pelvis, asociados a los ganglios simpáticos. La imagen morfológica, como en el caso de la TC, aporta un detalle anatómico excelente y una elevada sensibilidad, pero carece de especificidad, dado que pueden producirse dificultades a la hora de distinguir entre los tumores derivados del sistema nervioso simpático y otros tipos de tumores. A diferencia de la imagen anatómica, la imagen funcional (PET con 123I-MIBG, 68Ga-DOTA-TOC) aporta una alta sensibilidad y especificidad para la detección de tumores neuroendocrinos.

BackgroundTo our knowledge, data are lacking on the role of 18F-FDG PET/CT in the localization and prediction of neuroendocrine tumors, in particular the pheochromocytoma/paraganglioma (PCC/PGL) group.PurposeTo evaluate the role of 18F-FDG PET/CT in localizing and predicting the malignant potential of PCC/PGL.Material and MethodsTwenty-three consecutive patients with a history of PCC/PGL, presenting with symptoms related to catecholamine excess, underwent 18F-FDG PET/CT. Final confirmation of the diagnosis was made using the composite references. PET/CT findings were analyzed on a per-lesion basis and a per-patient basis. Tumor SUVmax was analyzed to predict the dichotomization of patient endpoints for the local disease and metastatic groups.ResultsWe investigated 23 patients (10 men, 13 women) with a mean age of 46.43 ± 3.70 years. Serum catecholamine levels were elevated in 82.60% of these patients. There were 136 sites (mean SUVmax: 16.39 ± 3.47) of validated disease recurrence. The overall sensitivities for diagnostic CT, FDG PET, and FDG PET/CT were 86.02%, 87.50%, and 98.59%, respectively. Based on the composite references, 39.10% of patients had local disease. There were significant differences in the SUVmax distribution between the local disease and metastatic groups; a significant correlation was noted when a SUVmax cut-off was set at 9.2 (P < 0.05).ConclusionIn recurrent PCC/PGL, diagnostic 18F-FDG PET/CT is a superior tool in the localization of recurrent tumors. Tumor SUVmax is a potentially useful predictor of malignant tumor potential.