title: The influence of computational strategy on prediction of mechanical stress in carotid atherosclerotic plaques: comparison of 2D structure-only, 3D structure-only, one-way and fully coupled fluid-structure interaction analyses.
abstract: BACKGROUND
  Compositional and morphological features of carotid atherosclerotic plaques provide complementary information to luminal stenosis in predicting clinical presentations. However, they alone cannot predict cerebrovascular risk. Mechanical stress within the plaque induced by cyclical changes in blood pressure has potential to assess plaque vulnerability. Various modeling strategies have been employed to predict stress, including 2D and 3D structure-only, 3D one-way and fully coupled fluid-structure interaction (FSI) simulations. However, differences in stress predictions using different strategies have not been assessed.
  
  
  METHODS
  Maximum principal stress (Stress-P1) within 8 human carotid atherosclerotic plaques was calculated based on geometry reconstructed from in vivo computerized tomography and high resolution, multi-sequence magnetic resonance images. Stress-P1 within the diseased region predicted by 2D and 3D structure-only, and 3D one-way FSI simulations were compared to 3D fully coupled FSI analysis.
  
  
  RESULTS
  Compared to 3D fully coupled FSI, 2D structure-only simulation significantly overestimated stress level (94.1 kPa [65.2, 117.3] vs. 85.5 kPa [64.4, 113.6]; median [inter-quartile range], p=0.0004). However, when slices around the bifurcation region were excluded, stresses predicted by 2D structure-only simulations showed a good correlation (R(2)=0.69) with values obtained from 3D fully coupled FSI analysis. 3D structure-only model produced a small yet statistically significant stress overestimation compared to 3D fully coupled FSI (86.8 kPa [66.3, 115.8] vs. 85.5 kPa [64.4, 113.6]; p<0.0001). In contrast, one-way FSI underestimated stress compared to 3D fully coupled FSI (78.8 kPa [61.1, 100.4] vs. 85.5 kPa [64.4, 113.7]; p<0.0001).
  
  
  CONCLUSIONS
  A 3D structure-only model seems to be a computationally inexpensive yet reasonably accurate approximation for stress within carotid atherosclerotic plaques with mild to moderate luminal stenosis as compared to fully coupled FSI analysis.
authors: University Departments of Radiology, University of Cambridge, UK.
authors: Yuan
authors: Y
authors: Huang
authors: University Departments of Radiology, University of Cambridge, UK; Department of Engineering, University of Cambridge, UK. Electronic address: zt215@cam.ac.uk.
authors: Zhongzhao
authors: Z
authors: Teng
authors: Department of Surgery, Cambridge University Hospitals NHS Foundation Trust, Cambridge, UK.
authors: Umar
authors: U
authors: Sadat
authors: University Departments of Radiology, University of Cambridge, UK.
authors: Martin J
authors: MJ
authors: Graves
authors: Division of Cardiovascular Medicine, University of Cambridge, UK.
authors: Martin R
authors: MR
authors: Bennett
authors: University Departments of Radiology, University of Cambridge, UK.
authors: Jonathan H
authors: JH
authors: Gillard
mesh_terms: D000368:Aged; D001794:Blood Pressure; D002339:Carotid Arteries / Q000503:physiopathology*; D003198:Computer Simulation; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D008955:Models, Cardiovascular; D058226:Plaque, Atherosclerotic / Q000503:physiopathology*; D012212:Rheology; D013314:Stress, Mechanical; D014057:Tomography, X-Ray Computed
keywords: Atherosclerosis; Carotid; Mechanics; Stress; Stroke