Evidence based classification of recommendations
| Class I | An imaging modality for which there is evidence for and/or general agreement that it is beneficial, useful, and effective in the management of acute stroke |
| Class II | An imaging modality for which there is conflicting evidence and/or divergence of opinion about the usefulness/efficacy in the management of acute stroke |
| Class IIa | Weight of evidence or opinion is in favor of the usefulness or efficacy of this imaging modality |
| Class IIb | The usefulness or efficacy is less well established by the evidence or expert opinion |
| Class III | An imaging test for which there is evidence and/or general agreement that it is not useful or effective, and in some cases may be harmful, in the management of acute stroke patients |