TY - JOUR A1 - Goubergrits, Leonid A1 - Osman, Jan A1 - Mevert, Ricardo A1 - Kertzscher, Ulrich A1 - Pöthkow, Kai A1 - Hege, Hans-Christian T1 - Turbulence in blood damage modeling JF - The International Journal of Artificial Organs N2 - 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. Y1 - 2016 U6 - https://doi.org/10.5301/ijao.5000476 VL - 39 IS - 4 SP - 147 EP - 210 ER - TY - JOUR A1 - Goubergrits, Leonid A1 - Schaller, Jens A1 - Kertzscher, Ulrich A1 - van den Bruck, Nils A1 - Pöthkow, Kai A1 - Petz, Christoph A1 - Hege, Hans-Christian A1 - Spuler, Andreas T1 - Statistical wall shear stress maps of ruptured and unruptured middle cerebral artery aneurysms JF - J. R. Soc. Interface Y1 - 2012 U6 - https://doi.org/10.1098/rsif.2011.0490 VL - 9 IS - 69 SP - 677 EP - 688 ER - TY - JOUR A1 - Goubergrits, Leonid A1 - Schaller, Jens A1 - Kertzscher, Ulrich A1 - Petz, Christoph A1 - Hege, Hans-Christian A1 - Spuler, Andreas T1 - 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 JF - Journal of Neurological Surgery, Part A: Central European Neurosurgery Y1 - 2013 U6 - https://doi.org/10.1055/s-0033-1342937 VL - 74 IS - 5 SP - 294 EP - 302 ER - TY - JOUR A1 - Goubergrits, Leonid A1 - Kertzscher, Ulrich A1 - Affeld, Klaus A1 - Petz, Christoph A1 - Stalling, Detlev T1 - Numerical Dye Washout Method as a Tool for Characterizing the Heart Valve Flow JF - ASAIO Journal Y1 - 2008 U6 - https://doi.org/10.1097/MAT.0b013e31815c5e38 VL - 54(1) SP - 50 EP - 57 ER - TY - CHAP A1 - Petz, Christoph A1 - Prohaska, Steffen A1 - Goubergrits, Leonid A1 - Kertzscher, Ulrich A1 - Hege, Hans-Christian T1 - Near-Wall Flow Visualization in Flattened Surface Neighborhoods T2 - Proc. Simulation and Visualization 2008 Y1 - 2008 UR - http://www.simvis.org/Tagung2008/sv-proceedings.html SP - 93 EP - 105 CY - Magdeburg, Germany ER - TY - JOUR A1 - Goubergrits, Leonid A1 - Thamsen, Bente A1 - Berthe, André A1 - Poethke, Jens A1 - Kertzscher, Ulrich A1 - Affeld, Klaus A1 - Petz, Christoph A1 - Hege, Hans-Christian A1 - Hoch, Heinrich A1 - Spuler, Andreas T1 - In Vitro Study of Near-Wall Flow in a Cerebral Aneurysm Model with and without Coils JF - American Journal of Neuroradiology Y1 - 2010 U6 - https://doi.org/10.3174/ajnr.A2121 VL - 31:8 SP - 1521 EP - 1528 ER - TY - JOUR A1 - Goubergrits, Leonid A1 - Spuler, Andreas A1 - Schaller, Jens A1 - Wiegmann, Nils A1 - Berthe, Andre A1 - Hege, Hans-Christian A1 - Affeld, Klaus A1 - Kertzscher, Ulrich T1 - In vitro study of hemodynamic treatment improvement: Hunterian ligation of a fenestrated basilar artery aneurysm after coiling JF - The International Journal of Artificial Organs N2 - 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. Y1 - 2014 U6 - https://doi.org/10.5301/ijao.5000314 VL - 37 IS - 4 SP - 325 EP - 335 ER - TY - CHAP A1 - Poethke, Jens A1 - Goubergrits, Leonid A1 - Kertzscher, Ulrich A1 - Spuler, Andreas A1 - Petz, Christoph A1 - Hege, Hans-Christian ED - Jos Vander Sloten, Pascal ED - Haueisen, Jens T1 - Impact of imaging modality for analysis of a cerebral aneurysm: Comparison between CT, MRI and 3DRA T2 - Proceedings of the 4th European Conference of the International Federation for Medical and Biological Engineering Y1 - 2008 U6 - https://doi.org/10.1007/978-3-540-89208-3 SP - 1889 EP - 1893 PB - Springer-Verlag CY - Antwerp, Belgium ER - TY - JOUR A1 - Goubergrits, Leonid A1 - Wellnhofer, Ernst A1 - Kertzscher, Ulrich A1 - Affeld, Klaus A1 - Petz, Christoph A1 - Hege, Hans-Christian T1 - Coronary Artery WSS Profiling Using a Geometry Reconstruction Based on Biplane Angiography JF - Annals of Biomedical Engineering Y1 - 2009 U6 - https://doi.org/s10439-009-9656-7 VL - 37 IS - 4 SP - 682 EP - 691 PB - Springer ER - TY - JOUR A1 - Goubergrits, Leonid A1 - Kertzscher, Ulrich A1 - Schöneberg, Bastian A1 - Wellnhofer, Ernst A1 - Petz, Christoph T1 - CFD analysis in an anatomically realistic coronary artery model based on non-invasive 3D imaging JF - Int. J. Cardiovasc. Imaging Y1 - 2008 U6 - https://doi.org/10.1007/s10554-007-9275-z VL - 24(4) SP - 411 EP - 421 ER -