title: Effect of image normalization on carotid plaque classification and the risk of ipsilateral hemispheric ischemic events: results from the asymptomatic carotid stenosis and risk of stroke study.
abstract: The aim of this study was to determine the effect of image normalization on plaque classification and the risk of ipsilateral ischemic neurologic events in patients with asymptomatic carotid stenosis. The first 1,115 patients recruited to the Asymptomatic Carotid Stenosis and Risk of Stroke (ACSRS) study with a follow-up of 6 to 84 months (mean 37.1 months) were included in this study. Duplex ultrasonography was used for grading the degree of internal carotid artery stenosis and for plaque characterization (types 1-5), which was performed before and after image normalization. One hundred sixteen ipsilateral ischemic hemispheric events occurred. Image normalization resulted in 60% of plaques being reclassified. Before image normalization, a high event rate was associated with all types of plaque. After image normalization, 109 (94%) of the events occurred in patients with plaque types 1 to 3. For patients with European Carotid Stenosis Trial (ECST) 70 to 99% diameter stenosis (equivalent to North American Symptomatic Carotid Endarterectomy Trial [NASCET] 50-99%) with plaque types 1 to 3, the cumulative stroke rate was 14% at 7 years (2% per year), and for patients with plaque types 4 and 5, the cumulative stroke rate was 0.9% at 7 years (0.14% per year). The results suggest that asymptomatic patients with plaque types 4 and 5 classified as such after image normalization are at low risk irrespective of the degree of stenosis.
authors.affiliation: Department of Vascular Surgery, Imperial College, London, UK. anicolai@cing.ac.cy
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Nicolaides
authors.forename: Stavros K
authors.initials: SK
authors.lastname: Kakkos
authors.forename: Maura
authors.initials: M
authors.lastname: Griffin
authors.forename: Michael
authors.initials: M
authors.lastname: Sabetai
authors.forename: Surinder
authors.initials: S
authors.lastname: Dhanjil
authors.forename: Daffyd J
authors.initials: DJ
authors.lastname: Thomas
authors.forename: George
authors.initials: G
authors.lastname: Geroulakos
authors.forename: Niki
authors.initials: N
authors.lastname: Georgiou
authors.forename: Susan
authors.initials: S
authors.lastname: Francis
authors.forename: Elena
authors.initials: E
authors.lastname: Ioannidou
authors.forename: Caroline J
authors.initials: CJ
authors.lastname: Doré
mesh_terms: D002343:Carotid Artery, Internal / Q000000981:diagnostic imaging*; D016893:Carotid Stenosis / Q000145:classification / Q000000981:diagnostic imaging*; D002544:Cerebral Infarction / Q000517:prevention & control; D005260:Female; D006801:Humans; D002546:Ischemic Attack, Transient / Q000517:prevention & control; D008297:Male; D012307:Risk Factors; D018608:Ultrasonography, Doppler / Q000592:standards*