Standardizing the estimation of ischemic regions can harmonize CT perfusion stroke imaging

OBJECTIVES: We aimed to evaluate the real-world variation in CT perfusion (CTP) imaging protocols among stroke centers and to explore the potential for standardizing vendor software to harmonize CTP images. METHODS: Stroke centers participating in a nationwide multicenter healthcare evaluation were requested to share their CTP scan and processing protocol. The impact of these protocols on CTP imaging was assessed by analyzing data from an anthropomorphic phantom with center-specific vendor software with default settings from one of three vendors (A-C): IntelliSpace Portal, syngoVIA, and Vitrea. Additionally, standardized infarct maps were obtained using a logistic model. RESULTS: Eighteen scan protocols were studied, all varying in acquisition settings. Of these protocols, seven, eight, and three were analyzed with center-specific vendor software A, B, and C respectively. The perfusion maps were visually dissimilar between the vendor software but were relatively unaffected by the acquisition settings. The median error [interquartile range] of the infarct core volumes (mL) estimated by the vendor software was - 2.5 [6.5] (A)/ - 18.2 [1.2] (B)/ - 8.0 [1.4] (C) when compared to the ground truth of the phantom (where a positive error indicates overestimation). Taken together, the median error [interquartile range] of the infarct core volumes (mL) was - 8.2 [14.6] before standardization and - 3.1 [2.5] after standardization. CONCLUSIONS: CTP imaging protocols varied substantially across different stroke centers, with the perfusion software being the primary source of differences in CTP images. Standardizing the estimation of ischemic regions harmonized these CTP images to a degree. CLINICAL RELEVANCE STATEMENT: The center that a stroke patient is admitted to can influence the patient's diagnosis extensively. Standardizing vendor software for CT perfusion imaging can improve the consistency and accuracy of results, enabling a more reliable diagnosis and treatment decision. KEY POINTS: • CT perfusion imaging is widely used for stroke evaluation, but variation in the acquisition and processing protocols between centers could cause varying patient diagnoses. • Variation in CT perfusion imaging mainly arises from differences in vendor software rather than acquisition settings, but these differences can be reconciled by standardizing the estimation of ischemic regions. • Standardizing the estimation of ischemic regions can improve CT perfusion imaging for stroke evaluation by facilitating reliable evaluations independent of the admission center

Patients with prior coronary artery bypass grafting have a poor outcome after myocardial infarction: an analysis of the VALsartan in acute myocardial iNfarcTion trial (VALIANT)

The number of patients presenting with an acute myocardial infarction (MI) and prior coronary artery bypass grafting (CABG) is increasing. We compared the baseline characteristics, treatment, and clinical outcomes of patients with and without prior CABG in the VALIANT trial. Of the 14 703 patients with heart failure (HF), left ventricular systolic dysfunction, or both enrolled in VALIANT, 1026 (7%) had prior CABG. Prior CABG patients were older [mean age (SD): 67 (10) vs. 65 (12) years; P less than 0.0001], had more comorbidity, and more frequent non-Q wave MI (66 vs. 30%; P less than 0.0001). At hospital presentation, prior CABG patients received less aspirin (82 vs. 90%; P less than 0.0001) and thrombolysis (21 vs. 36%; P less than 0.0001), but had a similar rate of primary percutaneous coronary intervention (14 vs. 15%; P = 0.2). Prior CABG patients were more likely to experience the composite outcome of cardiovascular death, MI, HF, resuscitated cardiac arrest, or stroke; 3 year Kaplan-Meier rate, 64 vs. 39% (adjusted hazard ratio 1.29, 95% confidence interval 1.17-1.43; P less than 0.0001). Patients with prior CABG had a worse clinical profile and experienced more fatal and non-fatal outcomes. Greater recognition is necessary for these high-risk patients including optimization of evidence-based secondary preventive therapy

Country specific cost comparisons from multinational clinical trials using empirical Bayesian shrinkage estimation: the Canadian ASSENT-3 economic analysis

The growing number of multinational clinical trials in which patient-level health care resource data are collected have raised the issue of which is the best approach for making inference for individual countries with respect to the between-treatment difference in mean cost. We describe and discuss the relative merits of three approaches. The first uses the random effects pooled estimate from all countries to estimate the difference for any particular country. The second approach estimates the difference using only the data from the specific country in question. Using empirical Bayes estimation a third approach estimates the country-specific difference using a variance-weighted linear sum of the estimates provided by the other two approaches. The approaches are illustrated and compared using the data from the ASSENT-3 trial. Copyright © 2005 John Wiley & Sons, Ltd.