title: Intra- and interreader reproducibility of magnetic resonance imaging for quantifying the lipid-rich necrotic core is improved with gadolinium contrast enhancement.
abstract: OBJECTIVE
  To test the hypothesis that intra- and interreader reproducibility for measuring the lipid-rich necrotic core (LR-NC) size is significantly improved with gadolinium (Gd) contrast-enhanced magnetic resonance imaging (CEMRI) compared to non-CEMRI.
  
  
  METHODS
  Thirty-seven individuals with >50% carotid artery stenosis underwent carotid MRI at 1.5T (pre- and postcontrast T1-weighted (T1W), T2-weighted (T2W), proton density-weighted (PDW), and three-dimensional time-of-flight (TOF) sequences). Two independent readers measured the mean area of the LR-NC from the precontrast images only, followed by a second measurement using the additional postcontrast images. One reader repeated the measurements after an interval of five months. Intra- and interreader reproducibility was analyzed by means of the intraclass correlation coefficient (ICC), coefficient of variation (CV), and standard deviation (SD).
  
  
  RESULTS
  The CV decreased from 33.7% to 8.8% for intrareader measurements of the LR-NC, and from 33.5% to 17.6% for interreader measurements. The SD was significantly smaller with CEMRI than with non-CEMRI (P = 0.003 and P = 0.006, respectively). The ICC increased from 0.94 to 0.99 and from 0.85 to 0.93 for the intra- and interreader measurements, respectively.
  
  
  CONCLUSIONS
  Reader reproducibility for in vivo MRI quantification of LR-NC size is significantly improved by the addition of Gd contrast in individuals with >50% carotid stenosis.
authors.affiliation: Department of Radiology, University of Washington, Seattle, Washington, USA.
authors.forename: Norihide
authors.initials: N
authors.lastname: Takaya
authors.forename: Jianming
authors.initials: J
authors.lastname: Cai
authors.forename: Marina S
authors.initials: MS
authors.lastname: Ferguson
authors.forename: Vasily L
authors.initials: VL
authors.lastname: Yarnykh
authors.forename: Baocheng
authors.initials: B
authors.lastname: Chu
authors.forename: Tobias
authors.initials: T
authors.lastname: Saam
authors.forename: Nayak L
authors.initials: NL
authors.lastname: Polissar
authors.forename: Jane
authors.initials: J
authors.lastname: Sherwood
authors.forename: Ricardo C
authors.initials: RC
authors.lastname: Cury
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Anders
authors.forename: Kay O
authors.initials: KO
authors.lastname: Broschat
authors.forename: Denise
authors.initials: D
authors.lastname: Hinton
authors.forename: Karen L
authors.initials: KL
authors.lastname: Furie
authors.forename: Thomas S
authors.initials: TS
authors.lastname: Hatsukami
authors.forename: Chun
authors.initials: C
authors.lastname: Yuan
mesh_terms: D001158:Arteries / Q000473:pathology; D016893:Carotid Stenosis / Q000473:pathology; D003287:Contrast Media / Q000494:pharmacology*; D005682:Gadolinium / Q000494:pharmacology*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008055:Lipids / Q000737:chemistry*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009336:Necrosis; D015588:Observer Variation; D015203:Reproducibility of Results
chemical_list: D003287:Contrast Media; D008055:Lipids; D005682:Gadolinium