title: Preliminary study of hemodynamics in human carotid bifurcation by computational fluid dynamics combined with magnetic resonance angiography.
abstract: BACKGROUND
  A longstanding hypothesis that correlates fluid dynamic forces and atherosclerotic disease has led to numerous analytical, numerical, and experimental studies over the years because it is very difficult to measure the hemodynamic variables of blood in vivo.
  
  
  OBJECTIVE
  To investigate the technique of visualization and quantitation of hemodynamic variables at carotid artery bifurcation in vivo by combining computational fluid dynamics (CFD) and vascular imaging.
  
  
  METHODS
  Twenty-six healthy volunteers underwent magnetic resonance (MR) angiography of the bilateral carotid artery by a 3.0T whole-body scanner. Hemodynamic variables at these carotid bifurcations were calculated and visualized by combining vascular imaging post-processing and CFD.
  
  
  RESULTS
  The average velocity of the carotid bifurcation in the systolic phase and the diastolic phase was 0.46+/-0.24 m/s and 0.23+/-0.05 m/s, respectively. Eddy current and back flows were observed at bifurcation and the lateral part of the proximal internal carotid arteries (ICA) and external carotid arteries (ECA), and the shapes of them changed with phases of the cardiac cycle, which were significant at the middle of the systolic phase and faded out quickly downstream of the ICA and ECA. The average range of wall shear stress (WSS) at the bifurcation was 4.36+/-1.32 Pa, and the maximum WSS was 18.02+/-4.11 Pa. The WSS map revealed a large region of low WSS at the carotid bulb and extended to the outer wall in the proximal end of the ICA (the lowest value was below 0.5 Pa), and there was also a small region of low WSS at the outer wall in the proximal end of the ECA.
  
  
  CONCLUSIONS
  CFD combined with vascular imaging can calculate and visualize hemodynamic variables at carotid bifurcation in vivo individually.
authors.affiliation: Department of Neuroradiology, Beijing Neurosurgical Institute, Beijing Tian Tan Hospital, Capital Medical University, Beijing, China.
authors.forename: Yunjing
authors.initials: Y
authors.lastname: Xue
authors.forename: Peyi
authors.initials: P
authors.lastname: Gao
authors.forename: Yan
authors.initials: Y
authors.lastname: Lin
authors.forename: Chengbo
authors.initials: C
authors.lastname: Dai
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001783:Blood Flow Velocity / Q000502:physiology*; D002339:Carotid Arteries / Q000502:physiology*; D005260:Female; D018056:Hemorheology; D006801:Humans; D018810:Magnetic Resonance Angiography; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D012039:Regional Blood Flow / Q000502:physiology*; D033081:Shear Strength; D014655:Vascular Resistance / Q000502:physiology