"There are 2 important radiologic variables that must be reported to help identify those patients that should be transferred: The ASPECT score and the volume of core ischemic injury.
I'm attaching an image that will aid you in calculating the ASPECT score on the non-contrast head CT.
Calculating the core ischemic volume is done off the DWI sequence and is straight forward: multiply the AP, transverse and SI dimensions of the stroke and divide by 2 (ABC/2).
Note that this does NOT mean that all acute stroke patients should get an emergent MRI, just those who are candidates for IA therapy (high ASPECT score and clot in a large vessel as seen on CTA) and the MRI should NOT delay administration of IV tPA which can be given prior to or on the way to MR."
Stroke protocol includes
Based on: Barber PA, Demchuk AM, Zhang J, Buchan AM, for the ASPECTS Study Group.
The validity and reliability of a novel quantitative CT score in predicting outcome in hyperacute stroke prior to thrombolytic therapy. Lancet 2000; 355:1670–1674.