The development of in vivo biomarkers sensitive to myelin disruption represents a major clinical need to be able to monitor the demyelination processes as well as the effect of remyelinating therapies in multiple sclerosis. The investigators recently proposed a technique, derived from the conventional magnetisation transfer (MT): inhomogeneous Magnetisation Transfer (ihMT). In preliminary studies, this simple-to-implement and robust technique has shown great sensitivity for evaluating the demyelination processes. The goal of the project is to evaluate the ability of ihMT to measure and describe the spontaneous demyelination and remyelination processes involved in active lesions in a population of patients with MS at the the disease onset.

The development of in vivo biomarkers sensitive to myelin disruption (demyelination and remyelination) represents a major clinical need to be able to monitor the demyelination processes as well as the effect of remyelinating therapies in multiple sclerosis. The investigators recently proposed a technique, derived from the conventional magnetisation transfer (MT): inhomogeneous Magnetisation Transfer (ihMT). In preliminary studies, this simple-to-implement and robust technique has shown great sensitivity for evaluating the demyelination processes. The goal of the project is to evaluate the ability of ihMT to measure and describe the spontaneous demyelination and remyelination processes involved in active lesions in a population of patients with MS at the the disease onset.

Inclusion Criteria:

• For Patients and Controls :

  • Adult patient, male and female, age 18 to 45
  • Patient affiliated with health insurance coverage,
  • Patient who signed a free and informed consent after receiving detailed, understandable and honest information,

• For patients only :

  • Patient with relapsing-remitting multiple sclerosis according to the McDonald 2010 criteria
  • Disease duration of less than 5 years
  • Patients treated or not treated with first-line disease modifying therapy
  • Detection of at least one post-Gadolinium injection active lesion identified on the initial brain MRI (T0)

Exclusion Criteria:

• For patients only :

  • Patients with a progressive form of MS other than the early relapsing-remitting form (primary progressive or secondary progressive)

• For Patients and Controls :

  • Patients with the usual contraindications for MRI (pacemaker, agitation, metal shards, claustrophobia)
  • Patients at risk of non-compliance to the exam: basic problems with understanding, confusion, involuntary movements, poor tolerance of prolonged supine position
  • Patients who are unable to give their consent: problems with understanding, lack of vigilance, confusion
  • Woman who is pregnant and breastfeeding
  • Patients with a history of neurological or psychiatric condition
  • Patients under guardianship or trusteeship