Background and objectives: Controversy exists about the optimal imaging technique in acute stroke. It was hypothesised that CT is comparable with DWI, when both are read systematically using quantitative scoring. Methods: Ischaemic stroke patients who had CT within six hours and DWI within seven hours of onset were included. Five readers used a quantitative scoring system (ASPECTS) to read the baseline (b) and follow up CT and DWI. Use of MRI in acute stroke was also assessed in patients treated with tissue plasminogen activator (tPA) by prospectively recording reasons for exclusion. Patients were followed clinically at three months.Results: bDWI and bCT were available for 100 consecutive patients (admission median NIHSS = 9). The mean bDWI and bCT ASPECTS were positively related (p,0.001). The level of interrater agreement ranged from good to excellent across all modalities and time periods. Bland-Altman plots showed more variability between bCT and bDWI than at 24 hours. The difference between bCT and bDWI was (2 ASPECTS points. Of bCT scans with ASPECTS 8-10, 81% had DWI ASPECTS 8-10. Patients with bCT ASPECTS of 8-10 were 1.9 times more likely to have a favourable outcome at 90 days than those with a score of 0-7 (95% CI 1.1 to 3.1, p = 0.002). The relative likelihood of favourable outcome with a bDWI ASPECTS 8-10 was 1.4 (95% CI 1.0 to 1.9, p = 0.10). Of patients receiving tPA 45% had contraindications to urgent MRI. Conclusion: The differences between CT and DWI in visualising early infarction are small when using ASPECTS. CT is faster and more accessible than MRI, and therefore is the better neuroimaging modality for the treatment of acute stroke.

The quantification of intracranial thrombus extent with the clot burden score predicts functional outcome, final infarct size and parenchymal hematoma risk acutely. The score needs external validation and could be useful for patient stratification in stroke trials.

Background Among asymptomatic patients with severe carotid artery stenosis but no recent stroke or transient cerebral ischaemia, either carotid artery stenting (CAS) or carotid endarterectomy (CEA) can restore patency and reduce long-term stroke risks. However, from recent national registry data, each option causes about 1% procedural risk of disabling stroke or death. Comparison of their long-term protective effects requires large-scale randomised evidence.Methods ACST-2 is an international multicentre randomised trial of CAS versus CEA among asymptomatic patients with severe stenosis thought to require intervention, interpreted with all other relevant trials. Patients were eligible if they had severe unilateral or bilateral carotid artery stenosis and both doctor and patient agreed that a carotid procedure should be undertaken, but they were substantially uncertain which one to choose. Patients were randomly allocated to CAS or CEA and followed up at 1 month and then annually, for a mean 5 years. Procedural events were those within 30 days of the intervention. Intention-to-treat analyses are provided. Analyses including procedural hazards use tabular methods. Analyses and meta-analyses of non-procedural strokes use Kaplan-Meier and log-rank methods. The trial is registered with the ISRCTN registry, ISRCTN21144362.

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 ASPECTSϭ0 to 3) than a difference of 0.6 in patients who had near-to-normal CT scans (follow-up ASPECTSϭ8 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, Pϭ0.12). 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, Pϭ0.09). Key Words: computed tomography Ⅲ stroke, acute Ⅲ thrombolysis C T is currently the modality of first choice for imaging patients with acute stroke. Although MRI has uncovered considerable information on the process of ischemic infarction, most patients with a stroke present to community hospitals without readily available MRI. 1 Although noncontrast CT (NCCT) was initially used to exclude intracranial hemorrhage and other nonstroke pathologies, advanced CT techniques are increasingly recognized as a modality to characterize early signs of ischemia. 2,3 With the use of multislice CT scanners, the potential information available from a CT scan has increased. 4 CT angiography and CT perfusion techniques can refine the current clinical criteria for patient selection for thrombolysis. 5 Source images from CT angiography (CTA-SI) can be rapidly obtained with minimal delays after a NCCT in the emergency room. 6,7,8 Although CTA has been shown to have value in identifying vessel occlusion, CTA-SI may also aid in the assessment of tissue status. Schramm et al found that the combination of CT, CTA, and CTA-SI was comparable to that of a magnetic resonance diffusion-weighted imaging. 9 CTA-SI can also be useful in predicting final infarct volume. 10,11 Brain tissue with a low cerebral blood volume appears as a region without enhancement on CTA-SI, effectively delineating the regions of ischemia. 11 The Alberta Stroke Program Early CT Score (ASPECTS) was developed as a grading instrument to assess e...