@misc{FriedrichRivoireScholzetal., author = {Friedrich, Janet and Rivoire, Julien and Scholz, Alexander and Wiegbert, and Terekov, Maxim and Kbrich, Rainer and Krenkel, Lars and Wagner, Claus and Schreiber, Laura Maria}, title = {Exploration of Gas Flow During High Frequency Oscillated Ventilation by 19F-Gas-MRI}, series = {Proceedings of the International Society for Magnetic Resonance in Medicine}, volume = {18}, journal = {Proceedings of the International Society for Magnetic Resonance in Medicine}, abstract = {To detect convective gas flow inside the large airways during high frequency oscillated ventilation (HFOV) the fluorinated contrast gas Heptafluoropropane was used for 19F-MRI. In a first study the comparison between constant flow measurements and Computational Fluid Dynamics (CFD) simulations provided a good agreement. In a following experiment oscillated flow was applied to a lung phantom consisting of ventilation bag and long pipe. The pressure wave inside the pipe was explored point-by-point and corresponding velocities were determined. With these experiments it could be shown for the first time that flow measurement during HFOV using fluorinated contrast gas is feasible.}, language = {en} } @inproceedings{KrenkelPennecotLenzetal., author = {Krenkel, Lars and Pennecot, Julien and Lenz, Christian and Feldmann, Daniel and Wagner, Claus}, title = {Optimierung der Hochfrequenz-Oszillationsventilation mittels str{\"o}mungsmechanischer Methoden und kontrastgasgest{\"u}tzter Magnetresonanztomografie - Teilprojekt: Rekonstruktion von Geometrien aus medizinischen Bilddaten und Erstellung von Modellen f{\"u}r experimentelle Str{\"o}mungsuntersuchungen}, series = {Laseranwendung in der Medizin, Erfassen und Verarbeiten kardiovaskul{\"a}rer Signale, protektive Beatmungskonzepte : 3. Dresdner Medizintechnik-Symposium - mit DFG-Forschungsschwerpunkt Protektive Beatmungskonzepte, 6. bis 9. Dezember 2010, Dresden}, booktitle = {Laseranwendung in der Medizin, Erfassen und Verarbeiten kardiovaskul{\"a}rer Signale, protektive Beatmungskonzepte : 3. Dresdner Medizintechnik-Symposium - mit DFG-Forschungsschwerpunkt Protektive Beatmungskonzepte, 6. bis 9. Dezember 2010, Dresden}, editor = {F{\"u}ssel, Jens and Koch, Edmund and Malberg, Hagen}, publisher = {TUDpress}, address = {Dresden}, isbn = {978-3-942710-02-2}, pages = {107 -- 114}, abstract = {Der vorliegende Artikel skizziert die neu entwickelte Prozesskette f{\"u}r detailgenaue Rekonstruktion von Geometrien anhand medizinischer Bilddaten sowie die Herstellung von transparenten Modellen f{\"u}r experimentelle Untersuchungen mit bildgebenden Str{\"o}mungsmessverfahren. Die Geometriedaten und Modelle werden f{\"u}r systematische Untersuchungen der komplexen Transportvorg{\"a}nge in den Atemwegen bei k{\"u}nstlicher Beatmung mittels Hochfrequenzoszillationsventilation (HFOV) verwendet.}, language = {en} } @incollection{ScholzKrenkelTerekhovetal., author = {Scholz, Alexander-Wigbert K. and Krenkel, Lars and Terekhov, Maxim and Friedrich, Janet and Rivoire, Julien and K{\"o}brich, Rainer and Wolf, Ursula and Kalthoff, Daniel and David, Matthias and Wagner, Claus and Schreiber, Laura Maria}, title = {Magnetic Resonance Imaging and Computational Fluid Dynamics of High Frequency Oscillatory Ventilation (HFOV)}, series = {Fundamental Medical and Engineering Investigations on Protective Artificial Respiration}, volume = {116}, booktitle = {Fundamental Medical and Engineering Investigations on Protective Artificial Respiration}, editor = {Hirschel, Ernst Heinrich and Schr{\"o}der, Wolfgang and Fujii, Kozo and Haase, Werner and Leer, Bram and Leschziner, Michael A. and Pandolfi, Maurizio and Periaux, Jacques and Rizzi, Arthur and Roux, Bernard and Shokin, Yurii I. and Klaas, Michael and Koch, Edmund and Schr{\"o}der, Wolfgang}, publisher = {Springer}, address = {Berlin, Heidelberg}, isbn = {978-3-642-20325-1}, doi = {10.1007/978-3-642-20326-8_7}, pages = {107 -- 128}, abstract = {In order to better understand the mechanisms of gas transport during High Frequency Oscillatory Ventilation (HFOV) Magnetic Resonance Imaging (MRI) with contrast gases and numerical flow simulations based on Computational Fluid Dynamics(CFD) methods are performed. Validation of these new techniques is conducted by comparing the results obtained with simplified models of the trachea and a first lung bifurcation as well as in a cast model of the upper central airways with results achieved from conventional fluid mechanical measurement techniques like e.g. Laser Doppler Anemometry (LDA). Further it is demonstrated that MRI of experimental HFOV is feasible and that Hyperpolarized 3He allows for imaging the gas re-distribution inside the lung. Finally, numerical results of oscillatory flow in a 3rd generation model of the lung as well as the impact of endotracheal tubes on the flow regime development in a trachea model are presented.}, language = {en} } @inproceedings{FriedrichFeldmannKrenkeletal., author = {Friedrich, Janet and Feldmann, Daniel and Krenkel, Lars and Wagner, Claus and Schreiber, Laura Maria}, title = {19F Gas Flow Measurement of C3F7H During Constant Flow and High Frequency Oscillatory Ventilation}, series = {Discovery, innovation \& application - advancing mr for improved health : ISMRM 21st Annual Meeting \& Exhibition ; SMRT 22nd Annual Meeting Salt Lake City, Utah, USA 20-26 April 2013}, volume = {21}, booktitle = {Discovery, innovation \& application - advancing mr for improved health : ISMRM 21st Annual Meeting \& Exhibition ; SMRT 22nd Annual Meeting Salt Lake City, Utah, USA 20-26 April 2013}, organization = {International Society for Magnetic Resonance in Medicine}, abstract = {The aim of the current study is the development of MRI methods that enable the investigation of gas flow mechanisms during high frequency oscillatory ventilation. This work includes flow measurements during three constant flows (19.9, 30.6 and 41.4 L min-1) and the comparison to direct numerical simulations (DNS) using a second-order-acurate finite-volume method and to data measured with a volume flow meter. 19F-MRI, DNS and flow meter data are in good agreement. Flow measurements during HFOV of 4 Hz were successfully performed and velocity profiles could be recorded at different phases of the ventilation cycle.}, language = {en} }