Biomechanics and Modeling in Mechanobiology

, Volume 16, Issue 1, pp 97–115 | Cite as

Wall shear stress at the initiation site of cerebral aneurysms

  • A. J. GeersEmail author
  • H. G. Morales
  • I. Larrabide
  • C. Butakoff
  • P. Bijlenga
  • A. F. Frangi
Original Paper


Hemodynamics are believed to play an important role in the initiation of cerebral aneurysms. In particular, studies have focused on wall shear stress (WSS), which is a key regulator of vascular biology and pathology. In line with the observation that aneurysms predominantly occur at regions of high WSS, such as bifurcation apices or outer walls of vascular bends, correlations have been found between the aneurysm initiation site and high WSS. The aim of our study was to analyze the WSS field at an aneurysm initiation site that was neither a bifurcation apex nor the outer wall of a vascular bend. Ten cases with aneurysms on the A1 segment of the anterior cerebral artery were analyzed and compared with ten controls. Aneurysms were virtually removed from the vascular models of the cases to mimic the pre-aneurysm geometry. Computational fluid dynamics (CFD) simulations were created to assess the magnitude, gradient, multidirectionality, and pulsatility of the WSS. To aid the inter-subject comparison of hemodynamic variables, we mapped the branch surfaces onto a two-dimensional parametric space. This approach made it possible to view the whole branch at once for qualitative evaluation. It also allowed us to empirically define a patch for quantitative analysis, which was consistent among subjects and encapsulated the aneurysm initiation sites in our dataset. To test the sensitivity of our results, CFD simulations were repeated with a second independent observer virtually removing the aneurysms and with a 20 % higher flow rate at the inlet. We found that branches harboring aneurysms were characterized by high WSS and high WSS gradients. Among all assessed variables, the aneurysm initiation site most consistently coincided with peaks of temporal variation in the WSS magnitude.


Aneurysm initiation Cerebral aneurysms Computational fluid dynamics Hemodynamics Image-based modeling Flow pulsatility Wall shear stress 



Financial support for this work was provided by the European Commission through the @neurIST project (FP6-IST-027703). We are very grateful to all collaborators within the @neurIST project. In particular, we would like to thank the following institutes for directly contributing to the construction of the @neurIST database (in alphabetical order): Advanced Simulation & Design GmbH, Rostock, Germany (C. Bludszuweit-Philipp); ANSYS Europe Ltd, Abingdon, UK (I. Jones, J. Penrose); BioComputing Competence Centre, Super Computing Solution s.r.l., Bologna, Italy (A. Chiarini, M. Viceconti); Hospital Clínic i Provincial de Barcelona, Barcelona, Spain (J. Blasco, J. Macho); Hospital General de Catalunya, Sant Cugat del Vallès, Spain (T. Sola, E. Vivas); Hôpitaux Universitaires de Genève, Geneva, Switzerland (P. Bijlenga, M. Jägersberg, K.O. Lovblad, A. Marcos-Gonzalez, V. Mendes-Pereira, A.P. Narata, A. Rogers, D.A. Rüfenacht, K. Schaller, B. Schatlo, P. Teta); Royal Hallamshire Hospital, Sheffield, UK (S. Coley, P. Lawford, U. Patel, P. Singh, A. Waterworth); Universitat Pompeu Fabra, Barcelona, Spain (M.L. Aguilar, H. Bogunovic, G. Engelbrecht, A.F. Frangi, A.J. Geers, M. Kim, I. Larrabide, H.G. Morales, C. Valencia-Muñoz, M.C. Villa-Uriol); University of Sheffield, Sheffield, UK (D.R. Hose, R. Lycett, A. Marzo). We would also like to thank Dr. Luca Antiga for his valuable technical advice and his support on the use of VMTK.

Conflict of interest



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Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  • A. J. Geers
    • 1
    Email author
  • H. G. Morales
    • 2
  • I. Larrabide
    • 3
  • C. Butakoff
    • 4
  • P. Bijlenga
    • 5
  • A. F. Frangi
    • 6
  1. 1.CISTIBUniversitat Pompeu FabraBarcelonaSpain
  2. 2.Medisys – Philips Research ParisParisFrance
  3. 3.PLADEMA-CONICET, UNICENTandilArgentina
  4. 4.PhySenseUniversitat Pompeu FabraBarcelonaSpain
  5. 5.Hôpitaux Universitaire de Genève et Faculté de Médecine de GenèveGenevaSwitzerland
  6. 6.CISTIBUniversity of SheffieldSheffieldUK

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