Inclusion Criteria:  patient> 18 years old Healthy volunteer Social insured in France Patient who signed the informed consent of the study  Exclusion Criteria:  Medical or surgical history of disease that may affect the central nervous system, or the spine History of spine or spinal cord trauma. Spinal osteoarthritis which can lead to a medullary hyper signal. Contraindication to MRI: claustrophobia, pace-maker, defibrillator, metallic foreign bodies, etc. Subjects benefiting from legal protection (curatorship, guardianship or safeguard of justice). Pregnant and / or breastfeeding woman.