title: Inter- and Intra-Observer Variability Assessment of in Vivo Carotid Plaque Burden Quantification Using Multi-Contrast Dark Blood MR Images.
abstract: The chapter presents the research to test the hypotheses that (1) vessel wall volume measurements from dark blood MR images with multiple contrast-weightings (T1W, T2W and PDW) are highly reproducible, and that (2) the intra-observer and inter-observer variability of carotid wall volume measurements will be less than those obtained with maximum wall area (MaxWA) measurements.
  
  
  METHODS
  Sixteen patients (aged 72 +/- 7years) with carotid stenosis documented by duplex ultrasound were recruited for the study. Dark blood T1W, PDW and T2W MR images were used to measure carotid wall volume and MaxWA by two independent observers for inter-observer and intra-observer variability assessment.
  
  
  RESULTS
  The intra-observer absolute difference of carotid wall volume for T1W, T2W and PDW images were 67.3 +/- 47.5 mm(3) (2.3 +/- 1.8%), 63.2 +/- 52.2 mm(3) (2.0 +/- 1.3%), and 69.8 +/- 45.2 mm(3) (2.4 +/- 1.7%) respectively. The inter-observer absolute difference of carotid wall volume for T1W, T2W and PDW images were 103.5 +/- 141.8 mm(3) (3.0 +/- 3.1%), 95.9 +/- 102.1 mm(3) (3.1 +/- 2.6%), and 132.1 +/- 87.8 mm(3) (4.3 +/- 2.7%) respectively. The intra-observer absolute difference of carotid MaxWA for T1W, T2W and PDW images were 6.9 +/- 5.0 mm(2) (4.2 +/- 2.9%), 5.1 +/- 4.2 mm(2) (3.1 +/- 2.3%) and 7.5 +/- 4.7 mm(2) (4.2 +/- 2.7%) respectively. The inter-observer absolute difference of carotid MaxWA for T1W, T2W and PDW images were 9.5 +/- 4.2 mm(2) (5.8 +/- 2.3%), 6.4 +/- 6.1 mm(2) (3.8 +/- 3.1%) and 10.8 +/- 7.3 mm(2) (6.1 +/- 3.7%) respectively. Both intra- and inter-observer variability in carotid volume measurement tend to be smaller than that in carotid MaxWA measurement with intraclass correlation coefficients ranged 0.932 to 0.987 for volume measurement and 0.822 to 0.946 for MaxWA measurement.
authors.affiliation: Case Western Reserve University, Cleveland, OH.
authors.forename: Shaoxiong
authors.initials: S
authors.lastname: Zhang
authors.forename: Jasjit S
authors.initials: JS
authors.lastname: Suri
authors.forename: Olivier
authors.initials: O
authors.lastname: Salvado
authors.forename: Yiping
authors.initials: Y
authors.lastname: Chen
authors.forename: Frank K
authors.initials: FK
authors.lastname: Wacker
authors.forename: David L
authors.initials: DL
authors.lastname: Wilson
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Duerk
authors.forename: Jonathan S
authors.initials: JS
authors.lastname: Lewin
mesh_terms: D002340:Carotid Artery Diseases; D016893:Carotid Stenosis; D006801:Humans; D015588:Observer Variation; D015203:Reproducibility of Results; D012720:Severity of Illness Index