TY  - THES
A1  - Oechsner, Markus
T1  - Morphologische und funktionelle <sup>1</sup>H-Magnetresonanztomographie der menschlichen Lunge bei 0.2 und 1.5 Tesla
T1  - Morphological and functional <sup>1</sup>H magnetic resonance tomography of the human lung at 0.2 and 1.5 tesla
N2  - Das Ziel dieser Arbeit war es, Methoden und Techniken für die morphologische und funktionelle Bildgebung der menschlichen Lunge mittels Kernspintomographie bei Feldstärken von 0,2 Tesla und 1,5 Tesla zu entwickeln und zu optimieren. Bei 0,2 Tesla wurde mittels der gemessenen Relaxationszeiten T1 und T2* eine 2D und eine 3D FLASH Sequenz zur Untersuchung der Lungenmorphologie optimiert. Sauerstoffgestützte Messungen der Relaxationszeiten T1 und T2* sowie eine SpinLabeling Sequenz liefern funktionelle Informationen über den Sauerstofftransfer und die Perfusion der Lungen. Bei 1,5 Tesla wurde die Lungenperfusion mittels MR-Kontrastmittel mit einer 2D und einer 3D Sequenz unter Verwendung der Präbolus Technik quantifiziert. Zudem wurden zwei MR-Navigationstechniken entwickelt, die es ermöglichen Lungenuntersuchungen unter freier Atmung durchzuführen und aus den Daten artefaktfreie Bilder zu rekonstruieren. Diese Techniken können in verschiedenste Sequenzen für die Lungenbildgebung implementiert werden, ohne dass die Messzeit dadurch signifikant verlängert wird.
N2  - The purpose of this thesis was to make a contribution to the development of lung MRI. While we developed and implemented new sequences and procedures both in the area of low-field MRI (0.2 Tesla) and 1.5 Tesla, we also took existing technologies into account by modifying and optimizing them for the working conditions at hand. In the process, we focused on techniques for both morphological and functional examination of the lung. Lung scans using an open 0.2 Tesla tomograph were an important component of this. Our first objective was to develop various methods for morphological and functional lung MRI, adapt them to altered conditions and further optimize them. The second objective was to contribute more in-depth research of contrast agent-based quantification of lung perfusion for the clinical standard of 1.5 Tesla. Additionally, we developed navigation methods which allow for scans of the lung under conditions of free breathing and without the use of external measurement devices.
KW  - NMR-Bildgebung
KW  - Lunge
KW  - 0.2 Tesla
KW  - Sauerstoff
KW  - Präbolus
KW  - Perfusion
KW  - freie Atmung
KW  - Navigator
KW  - Bilderzeugung
KW  - Bildgebendes Verfahren
KW  - oxygen-enhanced
KW  - spin labeling
KW  - contrast-enhanced
KW  - prebolus
KW  - free respiration
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-66942
ER  - 
TY  - JOUR
A1  - Hardcastle, Nicholas
A1  - Tomé, Wolfgang A.
A1  - Cannon, Donald M.
A1  - Brouwer, Charlotte L.
A1  - Wittendorp, Paul W. H.
A1  - Dogan, Nesrin
A1  - Guckenberger, Matthias
A1  - Allaire, Stéphane
A1  - Mallya, Yogish
A1  - Kumar, Prashant
A1  - Oechsner, Markus
A1  - Richter, Anne
A1  - Song, Shiyu
A1  - Myers, Michael
A1  - Polat, Bülent
A1  - Bzdusek, Karl
T1  - A multi-institution evaluation of deformable image registration algorithms for automatic organ delineation in adaptive head and neck radiotherapy
JF  - Radiation Oncology
N2  - Background: Adaptive Radiotherapy aims to identify anatomical deviations during a radiotherapy course and modify the treatment plan to maintain treatment objectives. This requires regions of interest (ROIs) to be defined using the most recent imaging data. This study investigates the clinical utility of using deformable image registration (DIR) to automatically propagate ROIs. 
Methods: Target (GTV) and organ-at-risk (OAR) ROIs were non-rigidly propagated from a planning CT scan to a per-treatment CT scan for 22 patients. Propagated ROIs were quantitatively compared with expert physician-drawn ROIs on the per-treatment scan using Dice scores and mean slicewise Hausdorff distances, and center of mass distances for GTVs. The propagated ROIs were qualitatively examined by experts and scored based on their clinical utility. 
Results: Good agreement between the DIR-propagated ROIs and expert-drawn ROIs was observed based on the metrics used. 94% of all ROIs generated using DIR were scored as being clinically useful, requiring minimal or no edits. However, 27% (12/44) of the GTVs required major edits. 
Conclusion: DIR was successfully used on 22 patients to propagate target and OAR structures for ART with good anatomical agreement for OARs. It is recommended that propagated target structures be thoroughly reviewed by the treating physician.
KW  - intensity-modulated radiotherapy
KW  - megavoltage computed-tomography
KW  - cancer
KW  - variability
KW  - strategies
KW  - risk
Y1  - 2012
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-134756
VL  - 7
IS  - 90
ER  -