title: Characterization of carotid plaque hemorrhage: a CT angiography and MR intraplaque hemorrhage study.
abstract: OBJECTIVE
  The main objective of this study was to evaluate CT angiographic (CTA) features that are able to predict the presence of intraplaque hemorrhage (IPH) as defined by MR-IPH.
  
  
  METHODS
  One hundred sixty-seven consecutive patients (mean age 69 years, SD 12.8; 58 females) underwent both MR-IPH and CTA within 3 weeks. MR-IPH, the gold standard, was performed at 1.5 T using a neurovascular phased-array coil as a coronal T1-weighted 3-dimensional fat-suppressed acquisition. CTA was performed using a 4-slice or a 64-slice CT machine and evaluated, blinded to MR-IPH findings, for carotid stenosis, plaque density, and plaque ulceration. Plaque density was defined as the mean attenuation of plaque at the site of maximum stenosis and 2 sections above and below. Plaque ulceration was defined as outpouching of contrast into the plaque at least 2 mm deep on any single plane.
  
  
  RESULTS
  Prevalence of IPH increased at higher degrees of carotid stenosis. Mean CT plaque density was higher for plaques with MRI-defined IPH (47 Hounsfield units) compared with without IPH (43 Hounsfield units; P=0.02). However, significant overlap between distributions of plaque densities limited the value of mean plaque density for prediction of IPH. CTA plaque ulceration had high sensitivity (80.0% to 91.4%), specificity (93.0% to 92.3%), positive predictive value (72.0% to 71.8%), and negative predictive value (95.0% to 97.9%) for prediction of IPH. Interobserver agreement for presence/absence of CTA plaque ulceration was excellent (kappa=0.80).
  
  
  CONCLUSIONS
  CTA plaque ulceration, but not mean CTA plaque density, was useful for prediction of IPH as defined by the MR-IPH technique.
authors.affiliation: Division of Neuroradiology, Department of Medical Imaging, Sunnybrook Health Sciences Centre, Toronto, Ontario, Canada.
authors.forename: Jean Marie
authors.initials: JM
authors.lastname: U-King-Im
authors.forename: Allan J
authors.initials: AJ
authors.lastname: Fox
authors.forename: Richard I
authors.initials: RI
authors.lastname: Aviv
authors.forename: Peter
authors.initials: P
authors.lastname: Howard
authors.forename: Robert
authors.initials: R
authors.lastname: Yeung
authors.forename: Alan R
authors.initials: AR
authors.lastname: Moody
authors.forename: Sean P
authors.initials: SP
authors.lastname: Symons
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography; D002339:Carotid Arteries / Q000000981:diagnostic imaging*; D016893:Carotid Stenosis / Q000000981:diagnostic imaging*; D005260:Female; D006470:Hemorrhage / Q000000981:diagnostic imaging*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D018709:Statistics, Nonparametric