title: Prevalence of Imaging Biomarkers to Guide the Planning of Acute Stroke Reperfusion Trials.
abstract: Imaging biomarkers are increasingly used as selection criteria for stroke clinical trials. The goal of our study was to determine the prevalence of commonly studied imaging biomarkers in different time windows after acute ischemic stroke onset to better facilitate the design of stroke clinical trials using such biomarkers for patient selection.
  
  
  
  This retrospective study included 612 patients admitted with a clinical suspicion of acute ischemic stroke with symptom onset no more than 24 hours before completing baseline imaging. Patients with subacute/chronic/remote infarcts and hemorrhage were excluded from this study. Imaging biomarkers were extracted from baseline imaging, which included a noncontrast head computed tomography (CT), perfusion CT, and CT angiography. The prevalence of dichotomized versions of each of the imaging biomarkers in several time windows (time since symptom onset) was assessed and statistically modeled to assess time dependence (not lack thereof).
  
  
  
  We created tables showing the prevalence of the imaging biomarkers pertaining to the core, the penumbra and the arterial occlusion for different time windows. All continuous imaging features vary over time. The dichotomized imaging features that vary significantly over time include: noncontrast head computed tomography Alberta Stroke Program Early CT (ASPECT) score and dense artery sign, perfusion CT infarct volume, and CT angiography collateral score and visible clot. The dichotomized imaging features that did not vary significantly over time include the thresholded perfusion CT penumbra volumes.
  
  
  
  As part of the feasibility analysis in stroke clinical trials, this analysis and the resulting tables can help investigators determine sample size and the number needed to screen.
authors.affiliation: From the Neuroradiology Section, Department of Radiology (B.J., Z.N., M.W.) and Department of Medicine, Quantitative Sciences Unit (R.L.B., M.D.), Stanford University School of Medicine, Palo Alto, CA; Department of Neurology, Stroke Center, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland (P.M., A.E.); and Department of Neurology, University of Pittsburgh, PA (T.J.).
authors.forename: Bin
authors.initials: B
authors.lastname: Jiang
authors.affiliation: From the Neuroradiology Section, Department of Radiology (B.J., Z.N., M.W.) and Department of Medicine, Quantitative Sciences Unit (R.L.B., M.D.), Stanford University School of Medicine, Palo Alto, CA; Department of Neurology, Stroke Center, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland (P.M., A.E.); and Department of Neurology, University of Pittsburgh, PA (T.J.).
authors.forename: Robyn L
authors.initials: RL
authors.lastname: Ball
authors.affiliation: From the Neuroradiology Section, Department of Radiology (B.J., Z.N., M.W.) and Department of Medicine, Quantitative Sciences Unit (R.L.B., M.D.), Stanford University School of Medicine, Palo Alto, CA; Department of Neurology, Stroke Center, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland (P.M., A.E.); and Department of Neurology, University of Pittsburgh, PA (T.J.).
authors.forename: Patrik
authors.initials: P
authors.lastname: Michel
authors.affiliation: From the Neuroradiology Section, Department of Radiology (B.J., Z.N., M.W.) and Department of Medicine, Quantitative Sciences Unit (R.L.B., M.D.), Stanford University School of Medicine, Palo Alto, CA; Department of Neurology, Stroke Center, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland (P.M., A.E.); and Department of Neurology, University of Pittsburgh, PA (T.J.).
authors.forename: Tudor
authors.initials: T
authors.lastname: Jovin
authors.affiliation: From the Neuroradiology Section, Department of Radiology (B.J., Z.N., M.W.) and Department of Medicine, Quantitative Sciences Unit (R.L.B., M.D.), Stanford University School of Medicine, Palo Alto, CA; Department of Neurology, Stroke Center, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland (P.M., A.E.); and Department of Neurology, University of Pittsburgh, PA (T.J.).
authors.forename: Manisha
authors.initials: M
authors.lastname: Desai
authors.affiliation: From the Neuroradiology Section, Department of Radiology (B.J., Z.N., M.W.) and Department of Medicine, Quantitative Sciences Unit (R.L.B., M.D.), Stanford University School of Medicine, Palo Alto, CA; Department of Neurology, Stroke Center, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland (P.M., A.E.); and Department of Neurology, University of Pittsburgh, PA (T.J.).
authors.forename: Ashraf
authors.initials: A
authors.lastname: Eskandari
authors.affiliation: From the Neuroradiology Section, Department of Radiology (B.J., Z.N., M.W.) and Department of Medicine, Quantitative Sciences Unit (R.L.B., M.D.), Stanford University School of Medicine, Palo Alto, CA; Department of Neurology, Stroke Center, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland (P.M., A.E.); and Department of Neurology, University of Pittsburgh, PA (T.J.).
authors.forename: Zack
authors.initials: Z
authors.lastname: Naqvi
authors.affiliation: From the Neuroradiology Section, Department of Radiology (B.J., Z.N., M.W.) and Department of Medicine, Quantitative Sciences Unit (R.L.B., M.D.), Stanford University School of Medicine, Palo Alto, CA; Department of Neurology, Stroke Center, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland (P.M., A.E.); and Department of Neurology, University of Pittsburgh, PA (T.J.). max.wintermark@gmail.com.
authors.forename: Max
authors.initials: M
authors.lastname: Wintermark
mesh_terms: D015415:Biomarkers; D002545:Brain Ischemia / Q000000981:diagnostic imaging*; D002986:Clinical Trials as Topic; D000072226:Computed Tomography Angiography / Q000379:methods*; D005240:Feasibility Studies; D006801:Humans; D015995:Prevalence; D015424:Reperfusion / Q000379:methods*; D012107:Research Design; D012189:Retrospective Studies; D020521:Stroke / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed
chemical_list: D015415:Biomarkers
keywords: biomarkers; computed tomographic angiography; hemorrhage; patient selection; stroke