title: Carotid MRI Detection of Intraplaque Hemorrhage at 3T and 1.5T.
abstract: OBJECTIVE
  Carotid intraplaque hemorrhage leads to plaque progression and ischemic events. Detection can be accomplished with 3T T1w sequences, but may be limited by false-positive lipid/necrosis. The purpose of this study was threefold: (1) to determine if magnetization-prepared rapid acquisition with gradient-echo (MPRAGE) detects intraplaque hemorrhage versus lipid/necrosis; (2) if 3T MPRAGE image quality is retained at 1.5T; and (3) to determine observer agreement.
  
  
  METHODS
  MPRAGE positive areas were compared to hemorrhage and lipid/necrosis areas from 100 carotid endarterectomy slides in 12 subjects using multivariable linear regression. Image quality was determined between 3T and 1.5T in 716 carotid arteries using t-tests and multivariable linear regression. Kappa analysis was used to determine agreement.
  
  
  RESULTS
  Intraplaque hemorrhage, not lipid/necrosis, was a significant predictor of MPRAGE positive area before and after adjusting for confounders (slope = .52 vs. .51, P < .001). Image quality at 3T was slightly lower than 1.5T (mean 3.87 vs. 4.34, P < .0001). 3T image quality remained slightly decreased before and after adjusting for confounders (slope = -.46 vs. -.41, P < .001). Kappa values for inter-/intraobserver agreement were .807/.919 at 3T and .803/.871 at 1.5T.
  
  
  CONCLUSIONS
  Carotid MPRAGE detects intraplaque hemorrhage, not lipid/necrosis. 3T image quality was retained at 1.5T with very good observer agreement.
authors.affiliation: Utah Center for Advanced Imaging Research, Department of Radiology, University of Utah School of Medicine, Salt Lake City, UT.
authors.forename: J
authors.initials: J
authors.lastname: Scott McNally
authors.forename: Hyo-Chun
authors.initials: HC
authors.lastname: Yoon
authors.forename: Seong-Eun
authors.initials: SE
authors.lastname: Kim
authors.forename: Krishna K
authors.initials: KK
authors.lastname: Narra
authors.forename: Michael S
authors.initials: MS
authors.lastname: McLaughlin
authors.forename: Dennis L
authors.initials: DL
authors.lastname: Parker
authors.forename: Gerald S
authors.initials: GS
authors.lastname: Treiman
mesh_terms: D002339:Carotid Arteries / Q000473:pathology*; D016893:Carotid Stenosis / Q000150:complications* / Q000473:pathology*; D002543:Cerebral Hemorrhage / Q000209:etiology* / Q000473:pathology*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D018810:Magnetic Resonance Angiography / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009336:Necrosis / Q000473:pathology; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: Carotid; Intraplaque Hemorrhage; MRI