@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}, volume = {31:8}, journal = {American Journal of Neuroradiology}, doi = {10.3174/ajnr.A2121}, pages = {1521 -- 1528}, year = {2010}, language = {en} } @inproceedings{GoubergritsPoethkePetzetal.2008, author = {Goubergrits, Leonid and P{\"o}thke, Jens and Petz, Christoph and Hege, Hans-Christian and Spuler, Andreas and Kertzscher, Ulrich}, title = {3D Bildgebung von zerebralen Aneurysmen}, booktitle = {Bildverarbeitung f{\"u}r die Medizin}, doi = {10.1007/978-3-540-78640-5_31}, pages = {153 -- 157}, year = {2008}, 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}, volume = {24(4)}, journal = {Int. J. Cardiovasc. Imaging}, doi = {10.1007/s10554-007-9275-z}, pages = {411 -- 421}, 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}, booktitle = {Proc. Simulation and Visualization 2008}, address = {Magdeburg, Germany}, pages = {93 -- 105}, year = {2008}, language = {en} } @article{GoubergritsTimmelAffeldetal.2006, author = {Goubergrits, Leonid and Timmel, Tobias and Affeld, Klaus and Petz, Christoph and Stalling, Detlev and Hege, Hans-Christian}, title = {Characterization of an artificial valve flow using the numerical dye washout visualization technique}, volume = {30(8)}, journal = {Artificial Organs}, pages = {642 -- 650}, year = {2006}, 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}, 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} } @article{GoubergritsSchallerKertzscheretal.2013, 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}, volume = {74}, journal = {Journal of Neurological Surgery, Part A: Central European Neurosurgery}, number = {5}, doi = {10.1055/s-0033-1342937}, pages = {294 -- 302}, year = {2013}, language = {en} } @article{HuttaryGoubergritsSchuetteetal.2017, author = {Huttary, Rudolf and Goubergrits, Leonid and Sch{\"u}tte, Christof and Bernhard, Stefan}, title = {Simulation, Identification and Statistical Variation in Cardiovascular Analysis (SISCA) - a Software Framework for Multi-compartment Lumped Modeling}, volume = {87}, journal = {Computers in Biology and Medicine}, doi = {10.1016/j.compbiomed.2017.05.021}, pages = {104 -- 123}, year = {2017}, language = {en} } @article{BrueningGoubergritsHepptetal.2017, author = {Br{\"u}ning, Jan and Goubergrits, Leonid and Heppt, Werner and Zachow, Stefan and Hildebrandt, Thomas}, title = {Numerical Analysis of Nasal Breathing - A Pilot Study}, volume = {33}, journal = {Facial Plastic Surgery}, number = {4}, doi = {doi:10.1055/s-0037-1603789}, pages = {388 -- 395}, year = {2017}, abstract = {Background: Currently, there is no fully sufficient way to differentiate between symptomatic and normal nasal breathing. Using the nose's total resistance is disputed as a valid means to objectify nasal airflow, and the need for a more comprehensive diagnostic method is increasing. This work's aim was to test a novel approach considering intranasal wall shear stress as well as static pressure maps obtained by computational fluid dynamics (CFD). Methods: X-ray computed tomography (CT) scan data of six symptom-free subjects and seven symptomatic patients were used. Patient-specific geometries of the nasal cavity were segmented from these data sets. Inspiratory and expiratory steady airflow simulations were performed using CFD. Calculated static pressures and wall shear stresses (WSS) were mapped onto a common template of the nasal septum, allowing for comparison of these parameters between the two patient groups. Results: Significant differences in wall shear stress distributions during the inspiratory phase could be identified between the two groups, whereas no differences were found for the expiratory phase. It is assumed that one essential feature of normal nasal breathing probably consists in distinctively different intranasal flow fields for inspiration and expiration. This is in accordance with previous investigations. Conclusion: The proposed method seems to be a promising tool for developing a new kind of patient-specific assessment of nasal breathing. However, more studies and a greater case number of data with an expanded focus, would be ideal.}, language = {en} } @article{GoubergritsOsmanMevertetal.2016, 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}, volume = {39}, journal = {The International Journal of Artificial Organs}, number = {4}, doi = {10.5301/ijao.5000476}, pages = {147 -- 210}, year = {2016}, 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} }