Diffusion Weighted Imaging Evaluation for Understanding Stroke Evolution Study-2 (DEFUSE-2)

Inclusion Criteria:

   1. Age 18 years and older

   2. Clinical diagnosis of ischemic stroke and a score of 5 or more points in the NIHSS.

   3. Planned to undergo intra-arterial (IA) therapy for acute hemispheric stroke (Either as
   primary therapy or as adjuvant therapy following intravenous tPA treatment)

   4. Planned to have a standard MRI including perfusion imaging and MR angiography of the
   circle of Willis (MRA) prior to IA therapy

   5. Intra-arterial thrombectomy can be started within 90 minutes of completion of MRI scan
   and within 12 hours of symptom onset. (Start of IA therapy is defined as the time of
   insertion of the femoral artery sheath; Time of brain scan is defined as the time that
   the scan is completed)

   6. Able to obtain informed consent (informed consent should be obtained prior to the
   baseline MRI scan).

Exclusion Criteria:

   1. Any pre-existing neurological illness resulting in a modified Rankin Scale Score of 3
   or higher prior to the qualifying stroke

   2. Pregnancy