TY - CHAP A1 - Petz, Christoph A1 - Stalling, Detlev A1 - Goubergrits, Leonid A1 - Affeld, Klaus A1 - Spuler, Andreas ED - Tolxdorff, Thomas T1 - Validierung von Strömungssimulationen in kardiovaskulären Anwendungen T2 - Bildverabeitung für die Medizin 2004 Y1 - 2004 SP - 356 EP - 360 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 - Hildebrandt, Thomas A1 - Goubergrits, Leonid A1 - Heppt, Werner A1 - Bessler, Stefan A1 - Zachow, Stefan T1 - Evaluation of the Intranasal Flow Field through Computational Fluid Dynamics (CFD) JF - Journal of Facial and Plastic Surgery Y1 - 2013 UR - https://www.thieme-connect.de/DOI/DOI?10.1055/s-0033-1341591 U6 - https://doi.org/10.1055/s-0033-1341591 VL - 29 IS - 2 SP - 93 EP - 98 PB - Thieme ER - TY - JOUR A1 - Goubergrits, Leonid A1 - Weber, Sarah A1 - Petz, Christoph A1 - Spuler, Andreas A1 - Pöthke, Jens A1 - Berthe, André A1 - Hege, Hans-Christian T1 - Wall-PIV as a Near Wall Flow Validation Tool for CFD JF - Journal of Visualization Y1 - 2009 VL - 12 IS - 3 SP - 241 EP - 250 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 - Brüning, Jan A1 - Goubergrits, Leonid A1 - Heppt, Werner A1 - Zachow, Stefan A1 - Hildebrandt, Thomas T1 - Numerical Analysis of Nasal Breathing - A Pilot Study JF - Facial Plastic Surgery N2 - 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. Y1 - 2017 U6 - https://doi.org/doi:10.1055/s-0037-1603789 VL - 33 IS - 4 SP - 388 EP - 395 ER - TY - JOUR A1 - Huttary, Rudolf A1 - Goubergrits, Leonid A1 - Schütte, Christof A1 - Bernhard, Stefan T1 - Simulation, Identification and Statistical Variation in Cardiovascular Analysis (SISCA) - a Software Framework for Multi-compartment Lumped Modeling JF - Computers in Biology and Medicine Y1 - 2017 U6 - https://doi.org/10.1016/j.compbiomed.2017.05.021 VL - 87 SP - 104 EP - 123 ER - 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 - CHAP A1 - Goubergrits, Leonid A1 - Pöthke, Jens A1 - Petz, Christoph A1 - Hege, Hans-Christian A1 - Spuler, Andreas A1 - Kertzscher, Ulrich T1 - 3D Bildgebung von zerebralen Aneurysmen T2 - Bildverarbeitung für die Medizin Y1 - 2008 U6 - https://doi.org/10.1007/978-3-540-78640-5_31 SP - 153 EP - 157 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 - 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 - 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 - 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 - JOUR A1 - Goubergrits, Leonid A1 - Timmel, Tobias A1 - Affeld, Klaus A1 - Petz, Christoph A1 - Stalling, Detlev A1 - Hege, Hans-Christian T1 - Characterization of an artificial valve flow using the numerical dye washout visualization technique JF - Artificial Organs Y1 - 2006 VL - 30(8) SP - 642 EP - 650 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 - 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 - 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 - JOUR A1 - Goubergrits, Leonid A1 - Hellmeier, Florian A1 - Bruening, Jan Joris A1 - Spuler, Andreas A1 - Hege, Hans-Christian A1 - Voss, Samuel A1 - Janiga, Gábor A1 - Saalfeld, Sylvia A1 - Beuing, Oliver A1 - Berg, Philipp T1 - Multiple Aneurysms AnaTomy CHallenge 2018 (MATCH): Uncertainty Quantification of Geometric Rupture Risk Parameters JF - BioMedical Engineering OnLine N2 - Background Geometric parameters have been proposed for prediction of cerebral aneurysm rupture risk. Predicting the rupture risk for incidentally detected unruptured aneurysms could help clinicians in their treatment decision. However, assessment of geometric parameters depends on several factors, including the spatial resolution of the imaging modality used and the chosen reconstruction procedure. The aim of this study was to investigate the uncertainty of a variety of previously proposed geometric parameters for rupture risk assessment, caused by variability of reconstruction procedures. Materials 26 research groups provided segmentations and surface reconstructions of five cerebral aneurysms as part of the Multiple Aneurysms AnaTomy CHallenge (MATCH) 2018. 40 dimensional and non-dimensional geometric parameters, describing aneurysm size, neck size, and irregularity of aneurysm shape, were computed. The medians as well as the absolute and relative uncertainties of the parameters were calculated. Additionally, linear regression analysis was performed on the absolute uncertainties and the median parameter values. Results A large variability of relative uncertainties in the range between 3.9 and 179.8% was found. Linear regression analysis indicates that some parameters capture similar geometric aspects. The lowest uncertainties < 6% were found for the non-dimensional parameters isoperimetric ratio, convexity ratio, and ellipticity index. Uncertainty of 2D and 3D size parameters was significantly higher than uncertainty of 1D parameters. The most extreme uncertainties > 80% were found for some curvature parameters. Conclusions Uncertainty analysis is essential on the road to clinical translation and use of rupture risk prediction models. Uncertainty quantification of geometric rupture risk parameters provided by this study may help support development of future rupture risk prediction models. Y1 - 2019 U6 - https://doi.org/10.1186/s12938-019-0657-y VL - 18 IS - 35 ER - TY - JOUR A1 - Hildebrandt, Thomas A1 - Bruening, Jan Joris A1 - Schmidt, Nora Laura A1 - Lamecker, Hans A1 - Heppt, Werner A1 - Zachow, Stefan A1 - Goubergrits, Leonid T1 - The Healthy Nasal Cavity - Characteristics of Morphology and Related Airflow Based on a Statistical Shape Model Viewed from a Surgeon’s Perspective JF - Facial Plastic Surgery N2 - Functional surgery on the nasal framework requires referential criteria to objectively assess nasal breathing for indication and follow-up. Thismotivated us to generate amean geometry of the nasal cavity based on a statistical shape model. In this study, the authors could demonstrate that the introduced nasal cavity’s mean geometry features characteristics of the inner shape and airflow, which are commonly observed in symptom-free subjects. Therefore, the mean geometry might serve as a reference-like model when one considers qualitative aspects. However, to facilitate quantitative considerations and statistical inference, further research is necessary. Additionally, the authorswere able to obtain details about the importance of the isthmus nasi and the inferior turbinate for the intranasal airstream. KW - statistical shape model KW - nasal cavity KW - nasal breathing KW - nasal airflow KW - isthmus nasi KW - inferior turbinate Y1 - 2019 U6 - https://doi.org/10.1055/s-0039-1677721 VL - 35 IS - 1 SP - 9 EP - 13 ER - TY - JOUR A1 - Hildebrandt, Thomas A1 - Bruening, Jan Joris A1 - Lamecker, Hans A1 - Zachow, Stefan A1 - Heppt, Werner A1 - Schmidt, Nora A1 - Goubergrits, Leonid T1 - Digital Analysis of Nasal Airflow Facilitating Decision Support in Rhinosurgery JF - Facial Plastic Surgery N2 - Successful functional surgery on the nasal framework requires reliable and comprehensive diagnosis. In this regard, the authors introduce a new methodology: Digital Analysis of Nasal Airflow (diANA). It is based on computational fluid dynamics, a statistical shape model of the healthy nasal cavity and rhinologic expertise. diANA necessitates an anonymized tomographic dataset of the paranasal sinuses including the complete nasal cavity and, when available, clinical information. The principle of diANA is to compare the morphology and the respective airflow of an individual nose with those of a reference. This enablesmorphometric aberrations and consecutive flow field anomalies to localize and quantify within a patient’s nasal cavity. Finally, an elaborated expert opinion with instructive visualizations is provided. Using diANA might support surgeons in decision-making, avoiding unnecessary surgery, gaining more precision, and target-orientation for indicated operations. KW - nasal airflow simulation KW - nasal breathing KW - statistical shape model KW - diANA KW - nasal obstruction KW - rhinorespiratory homeostasis Y1 - 2019 U6 - https://doi.org/10.1055/s-0039-1677720 VL - 35 IS - 1 SP - 1 EP - 8 ER - TY - JOUR A1 - Brüning, Jan A1 - Hildebrandt, Thomas A1 - Heppt, Werner A1 - Schmidt, Nora A1 - Lamecker, Hans A1 - Szengel, Angelika A1 - Amiridze, Natalja A1 - Ramm, Heiko A1 - Bindernagel, Matthias A1 - Zachow, Stefan A1 - Goubergrits, Leonid T1 - Characterization of the Airflow within an Average Geometry of the Healthy Human Nasal Cavity JF - Scientific Reports N2 - This study’s objective was the generation of a standardized geometry of the healthy nasal cavity. An average geometry of the healthy nasal cavity was generated using a statistical shape model based on 25 symptom-free subjects. Airflow within the average geometry and these geometries was calculated using fluid simulations. Integral measures of the nasal resistance, wall shear stresses (WSS) and velocities were calculated as well as cross-sectional areas (CSA). Furthermore, individual WSS and static pressure distributions were mapped onto the average geometry. The average geometry featured an overall more regular shape that resulted in less resistance, reduced wall shear stresses and velocities compared to the median of the 25 geometries. Spatial distributions of WSS and pressure of average geometry agreed well compared to the average distributions of all individual geometries. The minimal CSA of the average geometry was larger than the median of all individual geometries (83.4 vs. 74.7 mm²). The airflow observed within the average geometry of the healthy nasal cavity did not equal the average airflow of the individual geometries. While differences observed for integral measures were notable, the calculated values for the average geometry lay within the distributions of the individual parameters. Spatially resolved parameters differed less prominently. Y1 - 2020 UR - https://rdcu.be/b2irD U6 - https://doi.org/10.1038/s41598-020-60755-3 VL - 3755 IS - 10 ER -