BACKGROUND AND PURPOSE: SHT and ME are feared complications in patients with acute ischemic stroke. They occur Ͼ10 times more frequently in tPA-treated versus placebo-treated patients. Our goal was to evaluate the sensitivity and specificity of admission BBBP measurements derived from PCT in predicting the development of SHT and ME in patients with acute ischemic stroke.

BACKGROUND AND PURPOSE:The Patlak model has been applied to first-pass perfusion CT (PCT) data to extract information on blood-brain barrier permeability (BBBP) to predict hemorrhagic transformation in patients with acute stroke. However, the Patlak model was originally described for the delayed steady-state phase of contrast circulation. The goal of this study was to assess whether the first pass or the delayed phase of a contrast bolus injection better respects the assumptions of the Patlak model for the assessment of BBBP in patients with acute stroke by using PCT.

OBJECTIVE-To identify a set of computed tomography (CT) features of carotid atherosclerotic plaques that is significantly associated with ischemic stroke.METHODS-In a cross-sectional study, we retrospectively identified 136 consecutive patients admitted to our emergency department with suspected stroke who underwent a CT-angiogram (CTA) of the cervical and intracranial carotid arteries. CTA studies of the carotid arteries were processed automatically using a custom, CT-based automated computer classifier algorithm that quantitatively assesses a battery of carotid CT features. Acute stroke patients were categorized into "acute carotid stroke patients" and "non-acute carotid stroke patients" independent of carotid wall CT features, using the Causative Classification System for Ischemic Stroke, which includes the neuroradiologist's review of the imaging studies of the brain parenchyma and of the degree of carotid stenosis, and charted test results (such as EKG and Holter). Univariate followed by multivariate analyses were used to build models to differentiate between these patient groups and to differentiate between the infarct and unaffected sides in the "acute carotid stroke patients". A receiver operating characteristic curve analysis determined which model was most accurate.RESULTS-Forty "acute carotid stroke" patients and 50 "non-acute carotid stroke" patients were identified. Multivariate modeling identified a small number of the carotid wall CT features that were significantly associated with acute carotid stroke, including: wall volume, fibrous cap thickness, number and location of lipid clusters, and number of calcium clusters. INTERPRETATION-Patientswith acute carotid stroke demonstrate significant differences in the appearance of their carotid wall ipsilateral to the side of their infarct, when compared with either non-acute carotid stroke patients or the carotid wall contralateral to the infarct side. ObjectiveLuminal narrowing is the standard parameter used to report the extent and severity of carotid artery stenosis due to atherosclerosis. The widespread use of this measure is based primarily on the results of several randomized clinical trials that demonstrated a reduction in the risk of ischemic stroke in patients with luminal stenosis of ≥50% (assessed on conventional angiograms) after carotid endarterectomy compared with medical treatment alone.1 -4 However, ≥50%-carotid stenosis occurs in fewer than 5% of patients, whereas <50%-carotid stenosis is extremely frequent in the general population (70% in men and 60% in women over 64 years of age).5 , 6 In patients with <50% carotid stenosis, high-resolution lumenography provides limited insight into the associated risk of stroke because The goal of our retrospective study was to identify CT features of carotid atherosclerotic plaques that are significantly associated with the occurrence of ischemic stroke using this standardized, computerized assessment of CTA studies. Material and Methods Study DesignClinical and imaging data, obtained as par...

Use of dose-modulation techniques for neuroradiology CT examinations affords significant dose reduction while image quality is maintained.