Inclusion Criteria:  Patient over 18 years old To benefit from a medullary exploration planned by 3T MRI as part of a first evaluation or a reassessment of inflammatory involvement of the nevrax Express consent to participate in the study Affiliate or beneficiary of a social security scheme  Exclusion Criteria:  Patient benefiting from a legal protection measure Pregnant, parturient or breastfeeding woman Absolute or relative contraindication to MRI