title: Carotid bifurcation geometry is an independent predictor of early wall thickening at the carotid bulb.
abstract: OBJECTIVE
  Lumen geometry has long been suspected as a risk factor for atherosclerosis by virtue of its influence on blood flow disturbances. Confirmation of this geometric risk hypothesis has, however, proved challenging owing to possible effects of wall thickening on geometry and unproven links between candidate geometric variables and disturbed flow. The purpose of this study was to overcome these challenges.
  
  
  METHODS
  The study relied on imaging and risk factor data from progressively refined subsets of the Atherosclerosis Risk in Communities (ARIC) Carotid MRI study. Group 1 (n=467) included only nonstenotic cases having sufficient quality angiography for 3-dimensional analysis. Group 2 (n=346) excluded cases from group 1 having common and internal carotid artery wall thickness above previously identified thresholds for inward remodeling. Group 3 (n=294) excluded cases from group 2 having lumen irregularities and thus was least likely to include lumen geometries influenced by wall thickening.
  
  
  RESULTS
  Multiple linear regressions showed that for group 3, bifurcation flare and proximal curvature were independent predictors of internal carotid artery wall thickness, consistent with their previously demonstrated roles in predicting disturbed flow. For the broadest group 1, flare was an independent predictor of internal carotid artery wall thickness but with a sign change in regression coefficient reflecting effects of wall thickening on lumen geometry.
  
  
  CONCLUSIONS
  Carotid bifurcation geometry is an independent, albeit weak, predictor of its early wall thickening, but only when assumptions about geometric factors, and the influence of disease on them, are confronted. This highlights pitfalls of previous attempts to confirm geometric risk of atherosclerosis.
authors.affiliation: From the Biomedical Simulation Laboratory, Department of Mechanical and Industrial Engineering and Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada (P.B.B., D.A.S.); and Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University School of Medicine, Baltimore, MD (B.A.W.).
authors.forename: Payam B
authors.initials: PB
authors.lastname: Bijari
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Wasserman
authors.forename: David A
authors.initials: DA
authors.lastname: Steinman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000792:Angiography; D050197:Atherosclerosis / Q000453:epidemiology; D002339:Carotid Arteries / Q000473:pathology*; D002340:Carotid Artery Diseases / Q000473:pathology*; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D006801:Humans; D016014:Linear Models; D018810:Magnetic Resonance Angiography; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012307:Risk Factors
keywords: atherosclerosis; carotid arteries; hemodynamics; magnetic resonance imaging; risk factors