Are CT Angiography Source Images Accurate for Evaluating Infarct Volume?

Noncontrast computed tomography (NCCT) has been considered the standard test for determining eligibility for thrombolysis from the beginning of the thrombolytic era. CT angiography (CTA) reveals the cranio-cervical vessel and the occlusion site. Furthermore, the source image (SI) of the CTA (CTA-SI) reflects cerebral blood volume and can detect the infarct core as hypoattenuated areas with higher sensitivity than ischemic changes on NCCT. However, it was recently reported that the CTA-SI using fast acquisition protocol significantly overestimated the infarct core mostly on the basis of the poor collaterals. On the other hand, CTA-SI using standardized protocol was reported to be good predictor for final infarct extension. Imaging used in the setting of acute stroke should accurately address the presence and size of an irreversible ischemic core. Further studies are required to confirm whether another measure or adjustment in CTA-SI values can be more reliable for evaluating the infarct core.