The objective of this trial is to visualize blood brain barrier function and metabolic changes in the first days after ischemic stroke with new investigational MRI sequences.

In this study the investigators will be examining acute ischemic stroke patients on the first and second day after symptom onset using repetitive MRI examinations to visualize blood brain barrier function and metabolic changes of the brain in 5 sub-projects, each containing a specific MRI protocol with one of the following new MRI sequences:

1. T1-Dynamics (measuring disruptions of the blood-brain barrier)
2. pH-imaging (measuring metabolic changes, acidosis)
3. Resting-state MRI (measuring changes in the cerebral perfusion)
4. Quantitative MRI-Angiography (quantification of blood flow in single vessels)
5. Diffusion Tensor Imaging (DTI) for patients with Anterior Choroidal Artery (AChA)-Infarcts (quantification of damage of white matter tracts)

Each sub-projects will be conducted in blocks of a specific time span. Morphological outcome will be assessed at day 5-7. Clinical outcome will be assessed at day 5-7 and day 90. The association of the new imaging parameter with the clinical and morphological outcome measures will be analysed. No specific intervention is assigned to the subjects by the investigators of the study.

Inclusion Criteria:

• Suspected stroke or transient ischemic attack (TIA) within 24h from symptom onset

Exclusion Criteria:

• MRI contraindication, age < 18 years, intracranial hemorrhages

Primary care clinic. Patients presenting with acute (<24h) transient ischemic attack or stroke at the emergency ward, Charité Campus Benjamin Franklin