Acute stroke occurs in approximately 13.000 persons every year in Denmark, 10 - 15 % now receives intervenous thrombolytic therapy, which remains the most important acute treatment in ischaemic stroke. For more than a decade there has been an ongoing discussion if Computerized Tomography (CT) or Magnetic Resonance Imaging (MRI) were best before thrombolysis: Magnetic Resonance Imaging is superior in visualising ischaemia, but Computerized Tomography is quicker and more easily applicable.