Publications

2022
Waldmann, Moritz; Rüttgers, Mario; Lintermann, Andreas; Schröder, Wolfgang Virtual Surgeries of Nasal Cavities Using a Coupled Lattice-Boltzmann–Level-Set Approach Journal Article In: Journal of Engineering and Science in Medical Diagnostics and Therapy, vol. 5, iss. 3, 2022, ISSN: 2572-7958. Abstract \| Links \| BibTeX \| Tags: CFD Applications, Geometry, Lattice-Boltzmann method, Medizin, nasal cavity, Pipes, Pressure, Respiratory Flow Computation, Strömungssimulation, surgical indication @article{Waldmann2022, title = {Virtual Surgeries of Nasal Cavities Using a Coupled Lattice-Boltzmann–Level-Set Approach}, author = {Waldmann, Moritz and Rüttgers, Mario and Lintermann, Andreas and Schröder, Wolfgang}, url = {https://asmedigitalcollection.asme.org/medicaldiagnostics/article/doi/10.1115/1.4054042/1139371/Virtual-Surgeries-of-Nasal-Cavities-Using-a}, doi = {10.1115/1.4054042}, issn = {2572-7958}, year = {2022}, date = {2022-03-31}, urldate = {2022-03-31}, journal = {Journal of Engineering and Science in Medical Diagnostics and Therapy}, volume = {5}, issue = {3}, abstract = {Fluid mechanical properties of respiratory flow such as pressure loss, temperature distribution, or wall-shear stress characterize the physics of a nasal cavity. Simulations based on computational fluid dynamics (CFD) methods are able to deliver in-depth details on respiration. Integrating such tools into virtual surgery environments may support physicians in their decision-making process. In this study, a lattice-Boltzmann (LB) flow solver is coupled to a level-set (LS) method to modify the shape of a nasal cavity at simulation run time in a virtual surgery. The geometry of a presurgical nasal cavity obtained from computer tomography (CT) datasets is smoothly adapted toward a postsurgical geometry given by the surgeon using an interpolation approach based on a LS method. The influence of the modification on the respiratory flow is analyzed in silico. The methods are evaluated by simulating a virtual surgery of a stenotic pipe and juxtaposing the results to cases using static geometries and by comparing them to literature findings. The results for both the stenotic pipe and the nasal cavity are in perfect agreement with the expected outcomes. For the nasal cavity, a shape is found that reduces the nasal resistance by 25.3% for inspiration at a volumetric flow rate of V˙=250 ml/s. The heating capability is retained despite the geometry modification. The simulation results support the surgeon in evaluating a planned surgery and in finding an improved surgery for the patient.}, keywords = {CFD Applications, Geometry, Lattice-Boltzmann method, Medizin, nasal cavity, Pipes, Pressure, Respiratory Flow Computation, Strömungssimulation, surgical indication}, pubstate = {published}, tppubtype = {article} } Close Fluid mechanical properties of respiratory flow such as pressure loss, temperature distribution, or wall-shear stress characterize the physics of a nasal cavity. Simulations based on computational fluid dynamics (CFD) methods are able to deliver in-depth details on respiration. Integrating such tools into virtual surgery environments may support physicians in their decision-making process. In this study, a lattice-Boltzmann (LB) flow solver is coupled to a level-set (LS) method to modify the shape of a nasal cavity at simulation run time in a virtual surgery. The geometry of a presurgical nasal cavity obtained from computer tomography (CT) datasets is smoothly adapted toward a postsurgical geometry given by the surgeon using an interpolation approach based on a LS method. The influence of the modification on the respiratory flow is analyzed in silico. The methods are evaluated by simulating a virtual surgery of a stenotic pipe and juxtaposing the results to cases using static geometries and by comparing them to literature findings. The results for both the stenotic pipe and the nasal cavity are in perfect agreement with the expected outcomes. For the nasal cavity, a shape is found that reduces the nasal resistance by 25.3% for inspiration at a volumetric flow rate of V˙=250 ml/s. The heating capability is retained despite the geometry modification. The simulation results support the surgeon in evaluating a planned surgery and in finding an improved surgery for the patient. Close https://asmedigitalcollection.asme.org/medicaldiagnostics/article/doi/10.1115/1.[...] doi:10.1115/1.4054042 Close
2019
Akmenkalne, Liga; Prill, Matthias; Vogt, Klaus Nasal valve elastography: quantitative determination of the mobility of the nasal valve Journal Article In: Rhinology online, vol. Vol 2, pp. 81 - 86, 2019. Abstract \| Links \| BibTeX \| Tags: elastography, lateral nasal wall, nasal valve, rhinoplasty, surgical indication @article{AkmPrillVogt2019, title = {Nasal valve elastography: quantitative determination of the mobility of the nasal valve}, author = {Liga Akmenkalne and Matthias Prill and Klaus Vogt}, editor = {Rhinology online}, url = {https://www.rhinologyonline.org/Rhinology_online_issues/manuscript_50.pdf}, doi = {http://doi.org/10.4193/RHINOL/18.086}, year = {2019}, date = {2019-05-25}, journal = {Rhinology online}, volume = {Vol 2}, pages = {81 - 86}, abstract = {Background: The nasal valve area is the narrowest region of the entire upper airway. Numerous procedures and spreader devices are published to widen the nasal valve or to stabilize it, but the indications are based only on the surgeon’s experience. Methods: In 30 healthy volunteers the deflection of elastic steel elements touching the lower nasal side at its deepest point was precisely measured by means of strain gauges. The deflection was calibrated by standard calibration devices. A special 4-phase-rhinomanometer (4RHINO/ Rhinolab/Germany) with a protective face mask allowed simultaneous measurements of the airflow and differential pressure. All signals were recorded simultaneously on both sides. The measurements have been carried out as unilateral measurements according to anterior rhinomanometry. Results: Surprisingly the lateral nasal wall is already moving during quiet breathing. The airflow and its acceleration as well as the pressure difference generating a complete closure of the nose can be determined and has expectedly a high variance between individuals. Conclusions: The elastography confirms the loops in 4-phase-rhinomanometry as symptomatic for the nasal valve elongation and will after developing as medical product allow the systematic quantitative measurement of the influence of the nasal valve on the nasal air stream. }, keywords = {elastography, lateral nasal wall, nasal valve, rhinoplasty, surgical indication}, pubstate = {published}, tppubtype = {article} } Close Background: The nasal valve area is the narrowest region of the entire upper airway. Numerous procedures and spreader devices are published to widen the nasal valve or to stabilize it, but the indications are based only on the surgeon’s experience. Methods: In 30 healthy volunteers the deflection of elastic steel elements touching the lower nasal side at its deepest point was precisely measured by means of strain gauges. The deflection was calibrated by standard calibration devices. A special 4-phase-rhinomanometer (4RHINO/ Rhinolab/Germany) with a protective face mask allowed simultaneous measurements of the airflow and differential pressure. All signals were recorded simultaneously on both sides. The measurements have been carried out as unilateral measurements according to anterior rhinomanometry. Results: Surprisingly the lateral nasal wall is already moving during quiet breathing. The airflow and its acceleration as well as the pressure difference generating a complete closure of the nose can be determined and has expectedly a high variance between individuals. Conclusions: The elastography confirms the loops in 4-phase-rhinomanometry as symptomatic for the nasal valve elongation and will after developing as medical product allow the systematic quantitative measurement of the influence of the nasal valve on the nasal air stream. Close https://www.rhinologyonline.org/Rhinology_online_issues/manuscript_50.pdf doi:http://doi.org/10.4193/RHINOL/18.086 Close