title: Prevalence of American Heart Association type VI carotid atherosclerotic lesions identified by magnetic resonance imaging for different levels of stenosis as measured by duplex ultrasound.
abstract: OBJECTIVE
  Via magnetic resonance imaging (MRI), we sought to determine the prevalence of atherosclerotic American Heart Association type VI lesions (AHA-LT6) (lesions with luminal surface defect, hemorrhage/thrombus, or calcified nodule) in carotid arteries that represented all categories of stenosis as measured by duplex ultrasound.
  
  
  BACKGROUND
  Arterial stenosis alone has been shown to be a poor predictor of cardiovascular events. Autopsy studies suggest that features associated with AHA-LT6 lesions, rather than the degree of luminal narrowing, characterize the high-risk plaque.
  
  
  METHODS
  A total of 192 subjects underwent bilateral carotid artery magnetic resonance imaging (MRI) scans at 1.5T after evaluation with ultrasound to determine stenosis. After excluding arteries with a previous endarterectomy, poor image quality, or missing ultrasound data, there were 175 patients with 260 arteries available for analysis. The AHA lesion type was determined by the consensus opinion of 2 experienced carotid MRI reviewers.
  
  
  RESULTS
  In total, 96 of 260 (37.0%) arteries had >or=1 location with AHA-LT6. Of the arteries with AHA-LT6, 84.4% had hemorrhage, 45.8% had a ruptured fibrous cap, and 14.6% showed other type of complications. Prevalence of AHA-LT6 was an increasing sequence of 8.1% in the 37 arteries with 1% to 15% stenosis, 21.7% in the 60 arteries with 16% to 49% stenosis, 36.8% in the 114 arteries with 50% to 79% stenosis, and 77.6% in the 49 arteries with 80% to 99% stenosis.
  
  
  CONCLUSIONS
  Complicated AHA-LT6 are frequently found in arteries with <or=50% stenosis. These findings indicate that complex lesions develop in a substantial number of arteries in the absence of high-grade stenosis. Ongoing prospective studies will determine the predictive value of vulnerable plaque features, as visualized by MRI, for risk of subsequent ischemic events.
authors.affiliation: Department of Clinical Radiology, University of Munich, Grosshadern Campus, Munich, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Saam
authors.forename: Hunter R
authors.initials: HR
authors.lastname: Underhill
authors.forename: Baocheng
authors.initials: B
authors.lastname: Chu
authors.forename: Norihide
authors.initials: N
authors.lastname: Takaya
authors.forename: Jianming
authors.initials: J
authors.lastname: Cai
authors.forename: Nayak L
authors.initials: NL
authors.lastname: Polissar
authors.forename: Chun
authors.initials: C
authors.lastname: Yuan
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Hatsukami
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D050197:Atherosclerosis / Q000175:diagnosis* / Q000453:epidemiology; D002340:Carotid Artery Diseases / Q000150:complications / Q000175:diagnosis* / Q000453:epidemiology; D016893:Carotid Stenosis / Q000000981:diagnostic imaging; D003430:Cross-Sectional Studies; D005260:Female; D006470:Hemorrhage / Q000209:etiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D018616:Ultrasonography, Doppler, Duplex; D018084:Ultrasonography, Interventional