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Background and Purpose— The Alberta Stroke Program Early CT Score (ASPECTS) is a grading system to assess ischemic changes on CT in acute ischemic stroke. CT angiography–source images (CTA-SI) predict final infarct volume. We examined whether the final infarct ASPECTS and clinical outcome were more related to acute CTA-SI ASPECTS than to the acute noncontrast CT (NCCT) ASPECTS. Methods— ASPECTS was assigned by 2 raters on the acute NCCT, CTA-SI, and follow-up imaging. The mean baseline ASPECTS of acute NCCT and CTA-SI was compared with the follow-up ASPECTS. Rate ratios (RRs) were used to quantify the relationship between the dichotomized baseline ASPECTS (categorized as 0 to 7 versus 8 to 10) and favorable patient outcome. Results— Thirty-nine patients were recruited. Proximal occlusion (internal carotid artery or middle cerebral artery) was seen in 62%, M2 occlusion in 18%, and no occlusion was seen in 20% of patients. The median time between symptom onset and imaging was 1.9 (1.2 to 2.5) hours. There was a significantly larger difference of 1.4 between the mean baseline NCCT and CTA-SI ASPECTS in patients who had more ischemic changes (follow-up ASPECTS=0 to 3) than a difference of 0.6 in patients who had near-to-normal CT scans (follow-up ASPECTS=8 to 10). The rate of favorable outcome for acute NCCT ASPECTS of 8 to 10 was 51.8% versus 25.0% for 0 to 7 (RR, 2.1, 95% CI: 0.7 to 5.9, P =0.12). For acute CTA-SI ASPECTS of 8 to 10, the rate of favorable outcome was 58.8% versus 31.8% for 0 to 7 (RR, 1.8, 95% CI: 0.9 to 3.8, P =0.09). Conclusions— CTA-SI ASPECTS provides added information in the prediction of final infarct size.

To the Editor: In their abstract, Schramm et al, describe lesions seen on CT angiography source images (CTA-SI) as “demarcation of irreversible infarct.”1 We believe this description is inaccurate and have several comments regarding the utility and future study of CTA-SI. First, CTA-SI gives direct information about flow of contrast into the tissues and not about the viability of tissue. The inference that hypointense tissue is “irreversible infarct” may be time dependent. Irreversible damage may have occurred in most cases with clear hypointensity on CTA-SI at late time points after stroke onset, but this may not necessarily be true in the very early phase of infarct evolution. In Table 1, the authors report six cases in which the size of the area of CTA-SI hypointensity is bigger than the abnormal area of hyperintensity seen on the MR diffusion weighted image which was obtained following the CT. It has yet to be proven that volumes delineated on CTA-SI imply irreversibly damaged tissue in all cases and the relationship with time from stroke onset has not been clarified. Second, in the displayed examples, …