title: MRI measurements of carotid plaque in the atherosclerosis risk in communities (ARIC) study: methods, reliability and descriptive statistics.
abstract: OBJECTIVE
  To measure carotid plaque components using MRI and estimate reliability in the population-based Atherosclerosis Risk in Communities (ARIC) study.
  
  
  METHODS
  Contrast-enhanced high-resolution (0.51 x 0.58 x 2 mm(3)) MRI images were acquired through internal (ICA) and common carotid arteries (CCA) of 2066 ARIC participants at four sites. Sixty-one exams were repeated and 164 pairs had repeated interpretations. Plaque component thicknesses, areas and volumes over eight slices (1.6-cm segment) were measured. Intraplaque hemorrhage was recorded. Reliability was evaluated by intraclass correlations and kappa statistics.
  
  
  RESULTS
  There were 1769 successful MRI exams (mean age 71 years; 57% females; 81% white; 19% African-Americans). Repeat scan reliability was highest for CCA lumen area (0.94) and maximum wall thickness (0.89), ICA lumen area (0.89) and maximum wall thickness (0.77) and total wall volume (0.79), and lowest for small structures-core volume (0.30) and mean cap thickness (0.38). Overall reliability was primarily related to reader variability rather than scan acquisition. K's for presence of core, calcification and hemorrhage were fair to good. White men had the thickest plaques (average maximum ICA wall thickness = 2.3 mm) and the most cores (34%).
  
  
  CONCLUSIONS
  The most important limiting factor for MRI measurements of plaque components is reader variability. Measurement error depends largely on the analyzed structure's size.
authors.affiliation: The Russell H. Morgan Department of Radiology and Radiological Sciences, The Johns Hopkins University School of Medicine, Baltimore, MD, USA. bwasser@jhmi.edu
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Wasserman
authors.forename: Brad C
authors.initials: BC
authors.lastname: Astor
authors.forename: A Richey
authors.initials: AR
authors.lastname: Sharrett
authors.forename: Cory
authors.initials: C
authors.lastname: Swingen
authors.forename: Diane
authors.initials: D
authors.lastname: Catellier
mesh_terms: D016893:Carotid Stenosis / Q000175:diagnosis* / Q000453:epidemiology*; D015897:Comorbidity; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D015994:Incidence; D002537:Intracranial Arteriosclerosis / Q000175:diagnosis* / Q000453:epidemiology*; D018810:Magnetic Resonance Angiography / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D018570:Risk Assessment; D012307:Risk Factors; D012680:Sensitivity and Specificity