title: Use of B-mode ultrasound to examine preclinical markers of atherosclerosis: image quality may bias associations between adiposity and measures of vascular structure and function.
abstract: OBJECTIVE
  The purpose of this study was to examine the association between adiposity measures, ultrasound image quality, and preclinical markers of atherosclerosis in young adults.
  
  
  METHODS
  B-mode ultrasound was used to obtain common carotid intima-media thickness and common carotid artery distensibility of 2265 and 1313 adults aged 24 to 39 years in two population-based studies: the Cardiovascular Risk in Young Finns and Childhood Determinants of Adult Health studies. Qualitative assessments of ultrasound image quality were obtained from each study (scored as 1, excellent; 2, average; and 3, poor) based on the ability to detect arterial interfaces and the amount of noise present in the image.
  
  
  RESULTS
  Increased adiposity was associated with significantly increased odds (all P < .05) of average or poor carotid ultrasound image quality. Reduced image quality was associated with lower intima-media thickness in Young Finns (regression coefficient = -0.029; P = .01) and higher intima-media thickness in Childhood Determinants of Adult Health (regression coefficient = 0.013; P = .03) and lower distensibility levels in both studies (Young Finns, β = -.494; P < .01; Childhood Determinants of Adult Health: β = -.195; P < .01). We observed no differences (bias) in the association between adiposity measures and carotid intima-media thickness by image quality, but there was some evidence suggesting that the association between adiposity measures and carotid distensibility differed by image quality.
  
  
  CONCLUSIONS
  Adiposity affects ultrasound image quality and has the potential to bias associations between adiposity and preclinical markers of atherosclerosis. Studies examining adiposity and ultrasound-derived measures of atherosclerosis should consider taking steps during the design and analysis phase to adequately account for variations in image quality to avoid any potential bias.
authors.affiliation: Menzies Reserach Institute Tasmania, University of Tasmania, Hobart, Tasmania, Australia; Research Center of Applied and Preventive Cardiovascualr Medicine, University of Turku and Turku University Hospital, Turku, Finland; and Murdoch Children's Research Institute, Melbourne, Victoria, Australia. cmagnuss@utas.edu.au
authors.forename: Costan G
authors.initials: CG
authors.lastname: Magnussen
authors.forename: Russell
authors.initials: R
authors.lastname: Thomson
authors.forename: Markus
authors.initials: M
authors.lastname: Juonala
authors.forename: Jorma S A
authors.initials: JS
authors.lastname: Viikari
authors.forename: Terence
authors.initials: T
authors.lastname: Dwyer
authors.forename: Olli T
authors.initials: OT
authors.lastname: Raitakari
authors.forename: Alison
authors.initials: A
authors.lastname: Venn
mesh_terms: D000273:Adipose Tissue / Q000000981:diagnostic imaging*; D050154:Adiposity; D000328:Adult; D016477:Artifacts; D002339:Carotid Arteries / Q000000981:diagnostic imaging*; D002340:Carotid Artery Diseases / Q000000981:diagnostic imaging*; D059168:Carotid Intima-Media Thickness; D005260:Female; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D014463:Ultrasonography / Q000379:methods*; D055815:Young Adult