La TEP-TDM à la 18F-Dopa aurait-elle un rôle dans le suivi postopératoire des patients atteints de carcinome médullaire de la thyroïde ? Résultats préliminaires de l’expérience strasbourgeoise et revue de la littérature

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Aim Retrospective study to assess the value of fluorine-18 dihydroxyphenylalanine ( 18F-Dopa) positron emission tomography (PET)/computed tomography (CT) in the post-surgical follow-up of patients with history of medullary thyroid carcinoma (MTC) and biological suspicion of disease relapse. A review of the literature was also performed. Patients and methods Ten patients (23–71 years) with MTC previously treated by surgery were examined by at least one 18F-Dopa PET/CT. All patients presented with elevated serum calcitonin (130–9076 ng/l) and/or CEA (1.2–518 ng/ml) levels. 3D whole body PET/CT was performed 45 and 120 minutes after intravenous injection of 4 MBq/kg of 18F-Dopa. Scintigraphic images were visually interpreted. For quantitative analysis, maximum standardized uptake value (SUV max) per focus was employed. PET results were compared with histological findings and/or with the results of all other imaging procedures. Results Seven patients (70%) had a positive 18F-Dopa PET/CT. Twenty-five focal tracer accumulations were described. Histopathological confirmation of metastatic disease was obtained in four of the seven patients with pathologic 18F-Dopa PET/CT. No scintigraphic abnormalities were evidenced in the three other patients, whose conventional morphological imaging procedures were also negatives. Delayed PET/CT examinations didn’t increase sensitivity. No correlation between 18F-Dopa PET/CT results and both serum calcitonin and CEA levels was achieved. Conclusion Our results are in accordance with the existing literature, showing the potential role of 18F-Dopa PET/CT in the clinical management of patients with history of MTC and biological suspicion of relapse during post-surgical follow-up. Prospective studies including larger patient series are necessary to confirm the future place of 18F-Dopa PET/CT in follow-up of MTC.