@article{GoubergritsOsmanMevertetal., author = {Goubergrits, Leonid and Osman, Jan and Mevert, Ricardo and Kertzscher, Ulrich and P{\"o}thkow, Kai and Hege, Hans-Christian}, title = {Turbulence in blood damage modeling}, series = {The International Journal of Artificial Organs}, volume = {39}, journal = {The International Journal of Artificial Organs}, number = {4}, doi = {10.5301/ijao.5000476}, pages = {147 -- 210}, abstract = {Purpose: To account for the impact of turbulence in blood damage modeling, a novel approach based on the generation of instantaneous flow fields from RANS simulations is proposed. Methods: Turbulent flow in a bileaflet mechanical heart valve was simulated using RANS-based (SST k-ω) flow solver using FLUENT 14.5. The calculated Reynolds shear stress (RSS) field is transformed into a set of divergence-free random vector fields representing turbulent velocity fluctuations using procedural noise functions. To consider the random path of the blood cells, instantaneous flow fields were computed for each time step by summation of RSS-based divergence-free random and mean velocity fields. Using those instantaneous flow fields, instantaneous pathlines and corresponding point-wise instantaneous shear stresses were calculated. For a comparison, averaged pathlines based on mean velocity field and respective viscous shear stresses together with RSS values were calculated. Finally, the blood damage index (hemolysis) was integrated along the averaged and instantaneous pathlines using a power law approach and then compared. Results: Using RSS in blood damage modeling without a correction factor overestimates damaging stress and thus the blood damage (hemolysis). Blood damage histograms based on both presented approaches differ. Conclusions: A novel approach to calculate blood damage without using RSS as a damaging parameter is established. The results of our numerical experiment support the hypothesis that the use of RSS as a damaging parameter should be avoided.}, language = {en} } @article{GoubergritsSchallerKertzscheretal.2012, author = {Goubergrits, Leonid and Schaller, Jens and Kertzscher, Ulrich and van den Bruck, Nils and P{\"o}thkow, Kai and Petz, Christoph and Hege, Hans-Christian and Spuler, Andreas}, title = {Statistical wall shear stress maps of ruptured and unruptured middle cerebral artery aneurysms}, series = {J. R. Soc. Interface}, volume = {9}, journal = {J. R. Soc. Interface}, number = {69}, doi = {10.1098/rsif.2011.0490}, pages = {677 -- 688}, year = {2012}, language = {en} } @article{GoubergritsSchallerKertzscheretal., author = {Goubergrits, Leonid and Schaller, Jens and Kertzscher, Ulrich and Petz, Christoph and Hege, Hans-Christian and Spuler, Andreas}, title = {Reproducibility of Image-Based Analysis of Cerebral Aneurysm Geometry and Hemodynamics: An In-Vitro Study of Magnetic Resonance Imaging, Computed Tomography, and Three-Dimensional Rotational Angiography}, series = {Journal of Neurological Surgery, Part A: Central European Neurosurgery}, volume = {74}, journal = {Journal of Neurological Surgery, Part A: Central European Neurosurgery}, number = {5}, doi = {10.1055/s-0033-1342937}, pages = {294 -- 302}, language = {en} } @article{GoubergritsKertzscherAffeldetal.2008, author = {Goubergrits, Leonid and Kertzscher, Ulrich and Affeld, Klaus and Petz, Christoph and Stalling, Detlev}, title = {Numerical Dye Washout Method as a Tool for Characterizing the Heart Valve Flow}, series = {ASAIO Journal}, volume = {54(1)}, journal = {ASAIO Journal}, doi = {10.1097/MAT.0b013e31815c5e38}, pages = {50 -- 57}, year = {2008}, language = {en} } @inproceedings{PetzProhaskaGoubergritsetal.2008, author = {Petz, Christoph and Prohaska, Steffen and Goubergrits, Leonid and Kertzscher, Ulrich and Hege, Hans-Christian}, title = {Near-Wall Flow Visualization in Flattened Surface Neighborhoods}, series = {Proc. Simulation and Visualization 2008}, booktitle = {Proc. Simulation and Visualization 2008}, address = {Magdeburg, Germany}, pages = {93 -- 105}, year = {2008}, language = {en} } @article{GoubergritsThamsenBertheetal.2010, author = {Goubergrits, Leonid and Thamsen, Bente and Berthe, Andr{\´e} and Poethke, Jens and Kertzscher, Ulrich and Affeld, Klaus and Petz, Christoph and Hege, Hans-Christian and Hoch, Heinrich and Spuler, Andreas}, title = {In Vitro Study of Near-Wall Flow in a Cerebral Aneurysm Model with and without Coils}, series = {American Journal of Neuroradiology}, volume = {31:8}, journal = {American Journal of Neuroradiology}, doi = {10.3174/ajnr.A2121}, pages = {1521 -- 1528}, year = {2010}, language = {en} } @article{GoubergritsSpulerSchalleretal.2014, author = {Goubergrits, Leonid and Spuler, Andreas and Schaller, Jens and Wiegmann, Nils and Berthe, Andre and Hege, Hans-Christian and Affeld, Klaus and Kertzscher, Ulrich}, title = {In vitro study of hemodynamic treatment improvement: Hunterian ligation of a fenestrated basilar artery aneurysm after coiling}, series = {The International Journal of Artificial Organs}, volume = {37}, journal = {The International Journal of Artificial Organs}, number = {4}, doi = {10.5301/ijao.5000314}, pages = {325 -- 335}, year = {2014}, abstract = {Hunterian ligation affecting hemodynamics in vessels was proposed to avoid rebleeding in a case of a fenestrated basilar artery aneurysm after incomplete coil occlusion. We studied the hemodynamics in vitro to predict the hemodynamic changes near the aneurysm remnant caused by Hunterian ligation. A transparent model was fabricated based on three-dimensional rotational angiography imaging. Arteries were segmented and reconstructed. Pulsatile flow in the artery segments near the partially occluded (coiled) aneurysm was investigated by means of particle image velocimetry. The hemodynamic situation was investigated before and after Hunterian ligation of either the left or the right vertebral artery (LVA/RVA). Since post-ligation flow rate in the basilar artery was unknown, reduced and retained flow rates were simulated for both ligation options. Flow in the RVA and in the corresponding fenestra vessel is characterized by a vortex at the vertebrobasilar junction, whereas the LVA exhibits undisturbed laminar flow. Both options (RVA or LVA ligation) cause a significant flow reduction near the aneurysm remnant with a retained flow rate. The impact of RVA ligation is, however, significantly higher. This in vitro case study shows that flow reduction near the aneurysm remnant can be achieved by Hunterian ligation and that this effect depends largely on the selection of the ligated vessel. Thus the ability of the proposed in vitro pipe-line to improve hemodynamic impact of the proposed therapy was successfully proved.}, language = {en} } @inproceedings{PoethkeGoubergritsKertzscheretal.2008, author = {Poethke, Jens and Goubergrits, Leonid and Kertzscher, Ulrich and Spuler, Andreas and Petz, Christoph and Hege, Hans-Christian}, title = {Impact of imaging modality for analysis of a cerebral aneurysm: Comparison between CT, MRI and 3DRA}, series = {Proceedings of the 4th European Conference of the International Federation for Medical and Biological Engineering}, booktitle = {Proceedings of the 4th European Conference of the International Federation for Medical and Biological Engineering}, editor = {Jos Vander Sloten, Pascal and Haueisen, Jens}, publisher = {Springer-Verlag}, address = {Antwerp, Belgium}, doi = {10.1007/978-3-540-89208-3}, pages = {1889 -- 1893}, year = {2008}, language = {en} } @article{GoubergritsWellnhoferKertzscheretal.2009, author = {Goubergrits, Leonid and Wellnhofer, Ernst and Kertzscher, Ulrich and Affeld, Klaus and Petz, Christoph and Hege, Hans-Christian}, title = {Coronary Artery WSS Profiling Using a Geometry Reconstruction Based on Biplane Angiography}, series = {Annals of Biomedical Engineering}, volume = {37}, journal = {Annals of Biomedical Engineering}, number = {4}, publisher = {Springer}, doi = {s10439-009-9656-7}, pages = {682 -- 691}, year = {2009}, language = {en} } @article{GoubergritsKertzscherSchoenebergetal.2008, author = {Goubergrits, Leonid and Kertzscher, Ulrich and Sch{\"o}neberg, Bastian and Wellnhofer, Ernst and Petz, Christoph}, title = {CFD analysis in an anatomically realistic coronary artery model based on non-invasive 3D imaging}, series = {Int. J. Cardiovasc. Imaging}, volume = {24(4)}, journal = {Int. J. Cardiovasc. Imaging}, doi = {10.1007/s10554-007-9275-z}, pages = {411 -- 421}, year = {2008}, language = {en} }