It is difficult to determinate prognostic criteria of Multiple Sclerosis with conventional MRI insofar as physiopathology is not well-known: the precise sequences of events leading to plaque formation and axonal injury are still not completely understood.

Some elements involved in plaque formation can be studied thanks to MR techniques (cerebrospinal fluid and periveinular spaces, neuronal injury, microglia, and cerebral microcirculation's dysfunction).

This study aims at giving a better understanding of MS plaques' physiopathology, using data from modern MRI through a longitudinal followed up with weakly MR 3T examination.

The objective of this work are:

• study weakly development of the active MS plaque with multimodal MRI parameters using advanced MRI techniques: Veinography/3D FLAIR, Diffusion (CDA), Perfusion (CBV, CBF, MTT) MR Spectroscopy (NAA, myo-inositol, choline, lactate…) and enhanced 3DT1 sequences.
• define prognostic markers of MS aggressiveness ("black holes")
• Study development of MS plaque around venous structures.

Inclusion Criteria:

• Age between 18 and 50 years.
• Health coverage.
• Any form of MS defined by Mc Donald's criteria (2005).
• Patients having shown an enhanced plaque on a less than six month MRI examination.

Exclusion Criteria:

• Patients with an immunomodulating therapy like natalizumab (Tysabri) and intravenous immunosuppressive therapies. Other therapies will not be excluded from this study. For patients treated by systemic corticotherapy, a one-month delay will be necessary before a MRI examination.
• Cerebral microangiopathy (diabetes, arterial hypertension, vascularitis…)
• Patient with classical MRI contraindication like pace-maker, cardiac valvulosis, claustrophobia, allergy to contrast agent …
• Pregnancy or pregnancy desire.
• Patient with a low creatinine clearance <60 ml/mn