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Original research
4D-CT angiography versus 3D-rotational angiography as the imaging modality for computational fluid dynamics of cerebral aneurysms
  1. Nicole M Cancelliere1,
  2. Mehdi Najafi2,
  3. Olivier Brina3,
  4. Pierre Bouillot3,4,
  5. Maria I Vargas3,
  6. Karl-Olof Lovblad3,
  7. Timo Krings1,5,
  8. Vitor M Pereira1,5,
  9. David A Steinman2
  1. 1 Department of Medical Imaging, Toronto Western Hospital, Toronto, Ontario, Canada
  2. 2 Department of Mechanical & Industrial Engineering, University of Toronto, Toronto, Ontario, Canada
  3. 3 Department for Diagnostic and Interventional Neuroradiology, Hôpitaux Universitaires de Geneve, Geneva, Switzerland
  4. 4 École Polytechnique Fédérale de Lausanne (EPFL), EPFL Laboratory for Hydraulic Machines, Lausanne, Switzerland
  5. 5 Department of Neurosurgery, Toronto Western Hospital, Toronto, Ontario, Canada
  1. Correspondence to Professor David A Steinman; steinman{at}


Background and purpose Computational fluid dynamics (CFD) can provide valuable information regarding intracranial hemodynamics. Patient-specific models can be segmented from various imaging modalities, which may influence the geometric output and thus hemodynamic results. This study aims to compare CFD results from aneurysm models segmented from three-dimensional rotational angiography (3D-RA) versus novel four-dimensional CT angiography (4D-CTA).

Methods Fourteen patients with 16 cerebral aneurysms underwent novel 4D-CTA followed by 3D-RA. Endoluminal geometries were segmented from each modality using an identical workflow, blinded to the other modality, to produce 28 'original' models. Each was then minimally edited a second time to match length of branches, producing 28 additional 'matched' models. CFD simulations were performed using estimated flow rates for 'original' models (representing real-world experience) and patient-specific flow rates from 4D-CTA for 'matched' models (to control for influence of modality alone).

Results Overall, geometric and hemodynamic results were consistent between models segmented from 3D-RA and 4D-CTA, with correlations improving after matching to control for operator-introduced variability. Despite smaller 4D-CTA parent artery diameters (3.49±0.97 mm vs 3.78±0.92 mm for 3D-RA; p=0.005) and sac volumes (157 (37–750 mm3) vs 173 (53–770 mm3) for 3D-RA; p=0.0002), sac averages of time-averaged wall shear stress (TAWSS), oscillatory shear (OSI), and high frequency fluctuations (measured by spectral power index, SPI) were well correlated between 3D-RA and 4D-CTA 'matched' control models (TAWSS, R2=0.91; OSI, R2=0.79; SPI, R2=0.90).

Conclusions Our study shows that CFD performed using 4D-CTA models produces reliable geometric and hemodynamic information in the intracranial circulation. 4D-CTA may be considered as a follow-up imaging tool for hemodynamic assessment of cerebral aneurysms.

  • Brain
  • Aneurysm
  • Angiography
  • CT Angiography
  • Blood Flow
  • Computational Fluid Dynamics

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  • Twitter @NMCancelliere, @lovblad, @biomedsimlab

  • Contributors All authors contributed to the design of the study, the acquisition and/or analysis of the data, and the drafting and/or editing of the manuscript. All authors approved the final manuscript.

  • Funding This study was supported by grant G-16-00012564 from the Heart and Stroke Foundation of Canada. Computations were performed on Compute Ontario’s Niagara cluster, with priority core-hours provided by Compute Canada.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available upon reasonable request.