This study is a blinded randomized study. Randomization for treatment/not treatment with remote perconditioning takes place during transportation to the hospital. This is because the investigators' hypothesis states that remote perconditioning is neuro-protective and the effect is proportionally larger with early treatment. As the size of the effect is unknown, the investigators will use multiple magnetic resonance imaging (MRI) scans to determine the size of a potential neuro-protective effect.

The aims of this study are:

1. To describe method of remote perconditioning in clinical practice regarding feasibility. Pros and cons and potential limitations.
2. To estimate the size of the effect of remote perconditioning in combination with recombinant tissue plasminogen activator (rtPa) treatment within four and a half hours of onset of symptoms.

Final inclusion and informed consent takes place after first MRI in patients eligible for rtPA.

Follow-up MRI after 24h and 1 month. Clinical outcome at 3 months.

Inclusion Criteria:

• Significant ischemic stroke suspicion (NIHSS 1-24) and paresis of an extremity.
• Treatment with rtPa within 4.5 hours from debut of symptoms.
• Age above 18 (changed from 01.01.2010 to no upper age limit)
• Independent in daily living before the acute onset of symptoms. (mrs</=2)
• MR scan showing DWI lesion, consistent with acute ischemic stroke.

Exclusion Criteria:

• Contraindications for iv rtPA
• Onset of symptoms older than 4.5 hours
• Previous diseases of the brain: Intracranial aneurisms or arteriovenous malformations. Brain surgery or hemorrhagic stroke. Former ischemic stroke within the last 3 months.
• Heart diseases: Infectious endocarditis or suspicion of septic emboli, pericarditis, ventricular thrombosis, aneurisms of the heart wall or major heart failure.
• Serious diseases: Cancer, AIDS, dementia, significant abuse, renal failure, liver diseases such as liver failure, cirrhosis, portal hypertension, active hepatitis.
• Pregnancy
• Major ischemic stroke where the patient is unconscious.(NIHSS > 25).
• Symptoms suspect for migraine, Multiple sclerosis, TIA or another neurological disease than ischemic stroke.

MR scan:

• Contraindications for MRI scans
• Tumor cerebri, cerebral abscesses
• Known hypersensitivity to Gadovist or any of its ingredients, acute or chronic severe renal impairment (GFR < 30 ml/min/1.73m2), acute renal insufficiency of any severity due to the hepato-renal syndrome or in the perioperative liver transplantation period.
• Caution with using Gadovist to patients with severe cardiovascular disease, and only to be used after a risk-benefit assessment.
• Caution with using Gadovist in patients with low threshold for seizures.

Lab data:

• Blood glucose < 2, 8 mmol/l or > 22 mmol/l