Prospective Study Evaluating the Medullary Thyroid Cancer Management's Care Using PET F-DOPA in Patients With a High Level of Postoperative Residual Thyrocalcitonin

Inclusion Criteria: 1. Age \> or = 18 years. 2. Patient with medullary thyroid cancer (sporadic or hereditary form). 3. Patient treated by total thyroidectomy with uni or bi-lateral lymph node dissection (in the central and/or lateral neck compartment). 4. Patient with elevated thyrocalcitonin rate \> or = 150 pg/ml assessed within 6 weeks or more after surgery. 5. Patient with standard imaging assessment performed during 3 months before PET 18-FDOPA. 6. Standard imaging assessment including at least a cervical ultra-sound, a cervico-thoracic CT-scan and/or a cervico-thoraco-abdomino-pelvic CT-scan and a liver MRI. 7. Patient able to be followed at least 6 months after PET 18-FDOPA. 8. If women are breastfeeding, nursing should be discontinued during 24 hours after PET 18-FDOPA. 9. Patient must provide written informed consent prior to any specific procedure or assessment. 10. Patient must be affiliated to the French Social Security System. Exclusion Criteria: 1. Pregnant patient. 2. Post-operative radiotherapy initiated before PET 18-FDOPA. 3. Patient with PET 18-FDG performed within 24 hours before PET 18-FDOPA. 4. Participation in any other clinical trial for therapeutic use. 5. Patient with PET / CT-scan exam contra-indication. 6. Any serious and/or unstable pre-existing psychological, familial, geographic or social condition that could interfere with medical follow-up and compliance to study procedures. 7. Patient protected by law.