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      The Prognostic Value of CT Angiography and CT Perfusion in Acute Ischemic Stroke

      a , b , b , a , a , a , a , a , d , h , i , j , k , l , m , e , f , n , o , q , r , s , t , u , v , g , w , p , a , c , a

      Cerebrovascular Diseases

      S. Karger AG

      Clinical outcome, CT angiography, CT perfusion, Prognosis, Ischemic stroke, Prediction

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          Abstract

          Background: CT angiography (CTA) and CT perfusion (CTP) are important diagnostic tools in acute ischemic stroke. We investigated the prognostic value of CTA and CTP for clinical outcome and determined whether they have additional prognostic value over patient characteristics and non-contrast CT (NCCT). Methods: We included 1,374 patients with suspected acute ischemic stroke in the prospective multicenter Dutch acute stroke study. Sixty percent of the cohort was used for deriving the predictors and the remaining 40% for validating them. We calculated the predictive values of CTA and CTP predictors for poor clinical outcome (modified Rankin Scale score 3-6). Associations between CTA and CTP predictors and poor clinical outcome were assessed with odds ratios (OR). Multivariable logistic regression models were developed based on patient characteristics and NCCT predictors, and subsequently CTA and CTP predictors were added. The increase in area under the curve (AUC) value was determined to assess the additional prognostic value of CTA and CTP. Model validation was performed by assessing discrimination and calibration. Results: Poor outcome occurred in 501 patients (36.5%). Each of the evaluated CTA measures strongly predicted outcome in univariable analyses: the positive predictive value (PPV) was 59% for Alberta Stroke Program Early CT Score (ASPECTS) ≤7 on CTA source images (OR 3.3; 95% CI 2.3-4.8), 63% for presence of a proximal intracranial occlusion (OR 5.1; 95% CI 3.7-7.1), 66% for poor leptomeningeal collaterals (OR 4.3; 95% CI 2.8-6.6), and 58% for a >70% carotid or vertebrobasilar stenosis/occlusion (OR 3.2; 95% CI 2.2-4.6). The same applied to the CTP measures, as the PPVs were 65% for ASPECTS ≤7 on cerebral blood volume maps (OR 5.1; 95% CI 3.7-7.2) and 53% for ASPECTS ≤7 on mean transit time maps (OR 3.9; 95% CI 2.9-5.3). The prognostic model based on patient characteristics and NCCT measures was highly predictive for poor clinical outcome (AUC 0.84; 95% CI 0.81-0.86). Adding CTA and CTP predictors to this model did not improve the predictive value (AUC 0.85; 95% CI 0.83-0.88). In the validation cohort, the AUC values were 0.78 (95% CI 0.73-0.82) and 0.79 (95% CI 0.75-0.83), respectively. Calibration of the models was satisfactory. Conclusions: In patients with suspected acute ischemic stroke, admission CTA and CTP parameters are strong predictors of poor outcome and can be used to predict long-term clinical outcome. In multivariable prediction models, however, their additional prognostic value over patient characteristics and NCCT is limited in an unselected stroke population.

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          Most cited references 34

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          Perfusion-CT assessment of infarct core and penumbra: receiver operating characteristic curve analysis in 130 patients suspected of acute hemispheric stroke.

          Different definitions have been proposed to define the ischemic penumbra from perfusion-CT (PCT) data, based on parameters and thresholds tested only in small pilot studies. The purpose of this study was to perform a systematic evaluation of all PCT parameters (cerebral blood flow, volume [CBV], mean transit time [MTT], time-to-peak) in a large series of acute stroke patients, to determine which (combination of) parameters most accurately predicts infarct and penumbra. One hundred and thirty patients with symptoms suggesting hemispheric stroke < or =12 hours from onset were enrolled in a prospective multicenter trial. They all underwent admission PCT and follow-up diffusion-weighted imaging/fluid-attenuated inversion recovery (DWI/FLAIR); 25 patients also underwent admission DWI/FLAIR. PCT maps were assessed for absolute and relative reduced CBV, reduced cerebral blood flow, increased MTT, and increased time-to-peak. Receiver-operating characteristic curve analysis was performed to determine the most accurate PCT parameter, and the optimal threshold for each parameter, using DWI/FLAIR as the gold standard. The PCT parameter that most accurately describes the tissue at risk of infarction in case of persistent arterial occlusion is the relative MTT (area under the curve=0.962), with an optimal threshold of 145%. The PCT parameter that most accurately describes the infarct core on admission is the absolute CBV (area under the curve=0.927), with an optimal threshold at 2.0 ml x 100 g(-1). In a large series of 130 patients, the optimal approach to define the infarct and the penumbra is a combined approach using 2 PCT parameters: relative MTT and absolute CBV, with dedicated thresholds.
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            Analysis of pooled data from the randomised controlled trials of endarterectomy for symptomatic carotid stenosis

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              The independent predictive utility of computed tomography angiographic collateral status in acute ischaemic stroke.

              It is unknown whether collateral vessel status, as seen on computed tomography angiography, can predict the fate of penumbral tissue identified on perfusion computed tomography and thereby influence clinical outcome. We tested this hypothesis in consecutive patients who underwent perfusion computed tomography/computed tomography angiography within 6 h of anterior circulation stroke, who also had repeat perfusion/infarct volume imaging at 24 h, and modified Rankin Scale at 3 months. Collateral status was graded as good or reduced depending on the extent of contrast visualized distal to the occlusion on computed tomography angiography. 'Perfusion computed tomography mismatch' ratio was calculated from the ratio of the mean transit time lesion/cerebral blood volume lesion. Of 92 patients with proximal intracranial vessel occlusion, good collateral status (51/92) was significantly associated with reduced infarct expansion and more favourable functional outcomes (modified Rankin Scale 0-2). Significant univariate predictors of favourable outcome were good collateral status, major reperfusion at 24 h, presence of perfusion computed tomography mismatch (for a range of ratios: > or = 1.2, > or = 2, > or = 3, > or = 3.5) and baseline National Institutes of Health Stroke Scale score. Notably, none of the 37 patients with a perfusion computed tomography mismatch ratio < 3.0 had a favourable outcome. In patients with perfusion computed tomography mismatch, significant independent predictors of favourable outcome were good collateral status, major reperfusion and baseline National Institutes of Health Stroke Scale score. There was also a strong interaction between major reperfusion and good collateral status in the regression models. In patients with proximal vessel occlusion, perfusion computed tomography mismatch is a prerequisite for a favourable clinical response, but good collateral status appears a critical determinant of ultimate outcome, particularly if major reperfusion occurs.
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                Author and article information

                Journal
                CED
                Cerebrovasc Dis
                10.1159/issn.1015-9770
                Cerebrovascular Diseases
                Cerebrovasc Dis
                S. Karger AG (Basel, Switzerland karger@ 123456karger.com http://www.karger.com )
                1015-9770
                1421-9786
                November 2015
                21 October 2015
                : 40
                : 5-6
                : 258-269
                Affiliations
                aDepartment of Radiology, bDepartment of Neurology, Brain Center Rudolf Magnus, and cJulius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, dDepartment of Radiology, Academic Medical Center, Departments of eRadiology and fNeurology, VU University Medical Center, gDepartment of Neurology, Academic Medical Center, Amsterdam, Departments of hRadiology and iNeurology, St. Antonius Hospital, Nieuwegein, Departments of jRadiology and kNeurology, Leiden University Medical Center, Leiden, Departments of lRadiology and mNeurology, Catharina Hospital, Eindhoven, Departments of nRadiology and oNeurology, Erasmus MC University Medical Center, pDepartment of Radiology, St. Franciscus Hospital, Rotterdam, Departments of qRadiology and rNeurology, Rijnstate Hospital, Arnhem, Departments of sRadiology and tNeurology, Medical Center Haaglanden, The Hague, Departments of uRadiology and vNeurology, St. Elisabeth Hospital, Tilburg, wDepartment of Neurology, Radboud University Medical Center, Nijmegen, The Netherlands
                Article
                CED20150405-6258 Cerebrovasc Dis 2015;40:258-269
                10.1159/000441088
                26484857
                © 2015 S. Karger AG, Basel

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                Page count
                Figures: 2, Tables: 4, References: 60, Pages: 12
                Categories
                Original Paper

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