The aim of this study is to establish diagnostic and predictive biomarkers for patients with suspected acute stroke, that are transported by EMS as candidates for thrombolytic treatment. The study focuses on the ultra acute phase, <4.5 hours from symptom onset, including the prehospital setting. Analyses will include known biomarkers (e.g. GFAP, NR2 peptide) and a discovery phase for novel markers. Patient outcome will be evaluated at 3 month using the modified Rankin Scale (mRS).