title: Carotid artery intima-media thickness measurements in the youth: reproducibility and technical considerations.
abstract: BACKGROUND
  Carotid artery intima-media thickness (CIMT), a marker of atherosclerosis, is increased in youth at risk for future cardiovascular disease. Some pediatric studies have used CIMT as a primary outcome in clinical trials, yet data are limited on the standardization of methodology in children. The goal of this study was to evaluate reproducibility of CIMT measurements using two different measurement techniques.
  
  
  METHODS
  Carotid artery ultrasound studies of children and adolescents obtained as a component of a research study in Kawasaki syndrome were retrospectively analyzed. The CIMTs of both common carotid arteries (CCAs) were measured by one of two sonographers at the time in the cardiac cycle when resolution subjectively was determined to be optimal (Opt-CIMT). These sonographers blindly remeasured a random sample of studies of their own and each other's, using the same method. Another observer made CIMT measurements using exclusively frames on the R wave (R-CIMT). A fourth observer independently measured a random sample of studies twice with the R-CIMT method.
  
  
  RESULTS
  Carotid artery images from 184 subjects (mean age, 14.7 ± 2.2 years) were analyzed. The intraclass correlation coefficient for interobserver variability was 0.86 (95% confidence interval [CI], 0.69-0.94) compared with 0.85 (95% CI, 0.65-0.93) for the right and 0.86 (95% CI, 0.67-0.94) versus 0.95 (95% CI, 0.87-0.98) for the left CCA for Opt-CIMT and R-CIMT, respectively. R-CIMT was significantly thicker than Opt-CIMT (right CCA, 0.439 ± 0.030 vs 0.428 ± 0.024 mm, P < .001; left CCA, 0.446 ± 0.030 vs 0.434 ± 0.025 mm, P < .001).
  
  
  CONCLUSIONS
  Pediatric CIMT measurements have excellent reproducibility when the same methodology is applied but vary significantly throughout the cardiac cycle. This report highlights the need to standardize CIMT measurements in the youth and supports the use of electrocardiographic timing, as recommended in adults, in pediatric longitudinal studies.
authors.affiliation: Department of Cardiology, Children's Hospital Boston, Boston, Massachusetts; Department of Pediatrics, Harvard Medical School, Boston, Massachusetts; Division of Pediatric Cardiology, Department of Pediatrics, Stanford University, Palo Alto, California. Electronic address: tierneys@stanford.edu.
authors.forename: Elif Seda
authors.initials: ES
authors.lastname: Selamet Tierney
authors.affiliation: Department of Cardiology, Children's Hospital Boston, Boston, Massachusetts; Department of Pediatrics, Harvard Medical School, Boston, Massachusetts.
authors.forename: Kimberlee
authors.initials: K
authors.lastname: Gauvreau
authors.affiliation: Department of Cardiology, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts.
authors.forename: Michael R
authors.initials: MR
authors.lastname: Jaff
authors.affiliation: Department of Cardiology, Children's Hospital Boston, Boston, Massachusetts; Department of Pediatrics, Harvard Medical School, Boston, Massachusetts.
authors.forename: Dana
authors.initials: D
authors.lastname: Gal
authors.affiliation: Division of Pediatric Cardiology, Department of Pediatrics, Stanford University, Palo Alto, California.
authors.forename: Susan E
authors.initials: SE
authors.lastname: Nourse
authors.affiliation: Department of Cardiology, Children's Hospital Boston, Boston, Massachusetts; Department of Pediatrics, Harvard Medical School, Boston, Massachusetts.
authors.forename: Shari
authors.initials: S
authors.lastname: Trevey
authors.affiliation: Department of Cardiology, Children's Hospital Boston, Boston, Massachusetts; Department of Pediatrics, Harvard Medical School, Boston, Massachusetts.
authors.forename: Stephen
authors.initials: S
authors.lastname: O'Neill
authors.affiliation: Department of Cardiology, Children's Hospital Boston, Boston, Massachusetts; Department of Pediatrics, Harvard Medical School, Boston, Massachusetts.
authors.forename: Annette
authors.initials: A
authors.lastname: Baker
authors.affiliation: Department of Cardiology, Children's Hospital Boston, Boston, Massachusetts; Department of Pediatrics, Harvard Medical School, Boston, Massachusetts.
authors.forename: Jane W
authors.initials: JW
authors.lastname: Newburger
authors.affiliation: Department of Cardiology, Children's Hospital Boston, Boston, Massachusetts; Department of Pediatrics, Harvard Medical School, Boston, Massachusetts.
authors.forename: Steven D
authors.initials: SD
authors.lastname: Colan
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D002339:Carotid Arteries / Q000000981:diagnostic imaging*; D059168:Carotid Intima-Media Thickness; D002648:Child; D004452:Echocardiography / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D015588:Observer Variation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D055815:Young Adult
keywords: Atherosclerosis; Carotid artery IMT; Carotid artery ultrasound; Reproducibility; Variability; Youth