Our study aims to measure metabolic and functional parameters of the infarcted territory by multimodal cerebral MRI in patients diagnosed with unilateral proximal occlusion of the middle cerebral artery and treated by thrombectomy in order to correlate those parameters to clinical outcome (evaluated by modified Rankin score) at 3 months.

We aim to find early radiologic predictive factors for favorable clinical outcome in this population of patients.

The treatment of acute ischemic stroke in the setting of intracranial large artery occlusion and especially middle cerebral artery occlusion (MCAO) with intravenous tissue plasminogen activator (IV-tPA) is associated with low rates of recanalization and high rates of neurological morbidity and functional dependence.

In the last few years, endovascular intervention (mechanical thrombectomy) has proven its safety and its efficacy on clinical outcome in patients diagnosed with MCAO and is now commonly recommended.

However, in this population of patients treated by thrombectomy, very few predictive factors, except for the post-procedural recanalization score (TICI), do exist to foresee the variability of clinical outcome.

Tissue viability of the infarcted territory can be approached by the measure of metabolic and morphological parameters (Na+, H+, phosphore, diffusion imaging) which can be non-invasively done by multimodal MRI, as suggest by recently published studies.

Our study plans to measure these parameters between 12 and 24 hours after acute ischemic stroke in patients with MCAO treated by thrombectomy in order to correlate those parameters to clinical outcome at 3 months (modifier Rankin Score).

Inclusion Criteria:

• Patients aged ≥ 18 years old
• Hospitalized at the Poitiers University Hospital
• Acute middle cerebral artery occlusion diagnosed by CT-scan or MRI
• NIHSS score ≥ 6 at admission
• To be treated by thrombectomy with or without fibrinolysis
• Written information delivered to the patient or his relatives concerning the study and its benefit and risk

Exclusion Criteria:

• Patients or relatives whom a loyal information about the study cannot be given
• Patient with cognitive impairments before MRI.
• Patients who cannot undergo MRI because of contraindications
• Patients too deteriorated to tolerate one hour long exam