The aim of the trial is to study a radiating diagnosis agent used in post surgery when the biological assessment highlighted a residual disease.

This is an inter-regional multicentric, prospective study evaluating the benefit of PET F-DOPA imaging in involved node detection compared to standard imaging assessment in patient with medullary thyroid cancer.

The purpose of the study is to evaluate the impact and performance of a new PET / CT (computerized tomography ) tracer targeting dopamine receptor in patient with residual ganglionar biological disease after initial surgery of medullary thyroid cancer compared to standard imaging.

Obtained data will be compared to the "gold standard" based on :

• nodes cytology when they could be punctured
• histology when a new surgery will be recommended
• surveillance when the 2 first cases will be not applicable (imaging monitoring, evolution of 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.