title: Nonstenotic carotid plaque on CT angiography in patients with cryptogenic stroke.
abstract: OBJECTIVE
  To determine whether large (≥3 mm thick) but nonstenotic (<50%) carotid artery atherosclerotic plaque predominantly occurs ipsilateral rather than contralateral to cryptogenic stroke.
  
  
  METHODS
  This was a cross-sectional observational study. Using a stroke registry, we identified consecutive patients with anterior circulation embolic stroke of undetermined source (ESUS). Using CT angiography, we measured carotid plaque size (thickness, mm) and carotid artery stenosis (North American Symptomatic Carotid Endarterectomy Trial method) for each patient. We dichotomized plaque size at several predefined thresholds and calculated the frequency of plaque size above each threshold ipsilateral vs contralateral to stroke.
  
  
  RESULTS
  We included 85 patients with ESUS. Plaque with thickness ≥5 mm was present ipsilateral to stroke in 11% of patients, and contralateral in 1% (9/85 vs 1/85; p = 0.008). Plaque with thickness ≥4 mm was present ipsilateral to stroke in 19% of patients, and contralateral in 5% (16/85 vs 4/85; p = 0.002). Plaque with thickness ≥3 mm was present ipsilateral to stroke in 35% of patients, and contralateral in 15% (30/85 vs 13/85; p = 0.001). There was no difference in percentage stenosis ipsilateral vs contralateral to stroke (p = 0.98), and weak correlation between plaque size and stenosis (R(2) = 0.26, p < 0.001).
  
  
  CONCLUSIONS
  Large but nonstenotic carotid artery plaque is considerably more common ipsilateral than contralateral to cryptogenic stroke, suggesting that nonstenotic plaque is an underrecognized cause of stroke. We measured plaque size using CT angiography, a method that could be easily implemented in clinical practice.
authors.affiliation: From the Division of Neuroradiology, Department of Medical Imaging (J.M.C., S.D., D.M.M.), Division of Neurology, Department of Medicine (A.R.J.P., F.L.S.), and Department of Pathology (T.-R.K.), University Health Network and the University of Toronto; Dalla Lana School of Public Health (G.T.), University of Toronto; and Department of Medicine (G.T.), University Health Network and Mount Sinai Hospital, Toronto, Canada.
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Coutinho
authors.affiliation: From the Division of Neuroradiology, Department of Medical Imaging (J.M.C., S.D., D.M.M.), Division of Neurology, Department of Medicine (A.R.J.P., F.L.S.), and Department of Pathology (T.-R.K.), University Health Network and the University of Toronto; Dalla Lana School of Public Health (G.T.), University of Toronto; and Department of Medicine (G.T.), University Health Network and Mount Sinai Hospital, Toronto, Canada.
authors.forename: Sheldon
authors.initials: S
authors.lastname: Derkatch
authors.affiliation: From the Division of Neuroradiology, Department of Medical Imaging (J.M.C., S.D., D.M.M.), Division of Neurology, Department of Medicine (A.R.J.P., F.L.S.), and Department of Pathology (T.-R.K.), University Health Network and the University of Toronto; Dalla Lana School of Public Health (G.T.), University of Toronto; and Department of Medicine (G.T.), University Health Network and Mount Sinai Hospital, Toronto, Canada.
authors.forename: Alphonse R J
authors.initials: AR
authors.lastname: Potvin
authors.affiliation: From the Division of Neuroradiology, Department of Medical Imaging (J.M.C., S.D., D.M.M.), Division of Neurology, Department of Medicine (A.R.J.P., F.L.S.), and Department of Pathology (T.-R.K.), University Health Network and the University of Toronto; Dalla Lana School of Public Health (G.T.), University of Toronto; and Department of Medicine (G.T.), University Health Network and Mount Sinai Hospital, Toronto, Canada.
authors.forename: George
authors.initials: G
authors.lastname: Tomlinson
authors.affiliation: From the Division of Neuroradiology, Department of Medical Imaging (J.M.C., S.D., D.M.M.), Division of Neurology, Department of Medicine (A.R.J.P., F.L.S.), and Department of Pathology (T.-R.K.), University Health Network and the University of Toronto; Dalla Lana School of Public Health (G.T.), University of Toronto; and Department of Medicine (G.T.), University Health Network and Mount Sinai Hospital, Toronto, Canada.
authors.forename: Tim-Rasmus
authors.initials: TR
authors.lastname: Kiehl
authors.affiliation: From the Division of Neuroradiology, Department of Medical Imaging (J.M.C., S.D., D.M.M.), Division of Neurology, Department of Medicine (A.R.J.P., F.L.S.), and Department of Pathology (T.-R.K.), University Health Network and the University of Toronto; Dalla Lana School of Public Health (G.T.), University of Toronto; and Department of Medicine (G.T.), University Health Network and Mount Sinai Hospital, Toronto, Canada.
authors.forename: Frank L
authors.initials: FL
authors.lastname: Silver
authors.affiliation: From the Division of Neuroradiology, Department of Medical Imaging (J.M.C., S.D., D.M.M.), Division of Neurology, Department of Medicine (A.R.J.P., F.L.S.), and Department of Pathology (T.-R.K.), University Health Network and the University of Toronto; Dalla Lana School of Public Health (G.T.), University of Toronto; and Department of Medicine (G.T.), University Health Network and Mount Sinai Hospital, Toronto, Canada. danny.mandell@uhn.ca.
authors.forename: Daniel M
authors.initials: DM
authors.lastname: Mandell
mesh_terms: D000368:Aged; D002340:Carotid Artery Diseases / Q000000981:diagnostic imaging*; D016893:Carotid Stenosis / Q000000981:diagnostic imaging; D000072226:Computed Tomography Angiography; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D058226:Plaque, Atherosclerotic / Q000000981:diagnostic imaging*; D012042:Registries; D020521:Stroke / Q000000981:diagnostic imaging*