@phdthesis{Grathwohl2021,
  author    = {Grathwohl, Daniela},
  title     = {Quantitative Sonoelastographie der Leber bei Kindern und Jugedlichen mit Cystischer Fibrose},
  doi       = {10.25972/OPUS-25062},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-250621},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2021},
  abstract  = {Morbidit{\"a}t und Mortalit{\"a}t der Lebererkrankung im Rahmen der Cystischen Fiborse (Cystic fibrosis liver disease, CFLD) sind vornehmlich von Ausmaß und Progredienz der Leberfibrose abh{\"a}ngig. Aufgrund der fehlenden Genauigkeit der bisherigen diagnostischen Verfahren werden viele der an CF erkrankten Menschen erst in fortgeschrittenen Stadien diagnostiziert. Schwere Komplikationen einer Leberzirrhose treten h{\"a}ufig bereits im Kindesalter auf. Die Quantitative Sonoelastographie, hier die Acoustic Radiation Force Impulse (ARFI)-Elastographie, ist ein vielversprechendes, nicht-invasives und strahlenfreies Verfahren zur Messung der Gewebesteifigkeit. Anhand dieser retrospektiven, monozentrischen Studie soll die ARFI-Elastographie im Hinblick auf den klinischen Einsatz bei der CFLD-Diagnostik untersucht werden. Es wurde eruiert, ob sich mittels ARFI-Elastographie R{\"u}ckschl{\"u}sse auf eine CFLD und deren Schweregrade ziehen lassen. Hierf{\"u}r wurden die ARFI-Messungen verschiedener Lebersegmente von 62 an CF erkrankten und 19 lebergesunden Kindern und Jugendlichen verglichen. Zudem erfolgte die Korrelation der Ergebnisse mit zwei etablierten klinischen Leberfibrose-Scores (APRI, Williams-Score). Im Patientenkollektiv konnten tendenziell erh{\"o}hte Scherwellengeschwindigkeiten, entsprechend einer fibrotischen Aktivit{\"a}t, gemessen werden. Die transkostale Messposition in Segment VII/VIII (TC VII/VIII) erwies sich als zuverl{\"a}ssigste Position zur Differenzierung zwischen einer CF-Hepatopathie und einem gesunden Leberparenchym. Hingegen war das Errechnen von Cut-off Werten zur Graduierung von Fibrosestadien nicht m{\"o}glich. Auch war keine Korrelation zu Leberfiborsescores feststellbar. Insgesamt zeigt sich, dass die Diagnosestellung einer CFLD aktuell nur in Kombination mit bisherigen Messmethoden wie der klinischen Untersuchung, der Laboranalytik und der Sonographie m{\"o}glich ist. Die Interpretation der ARFI-cut-off Werte bleibt aufgrund mangelnder Sensitivit{\"a}t und Spezifit{\"a}t und vor dem Hintergrund der CF-typischen heterogenen Leberpathologie erschwert. Die ARFI-Elastographie kann als zus{\"a}tzlicher Baustein in der Diagnostik der CFLD, bei unklaren Befundkonstellationen oder zum Therapie-Monitoring herangezogen werden. Um einen klaren klinischen Einsatz in der Routinediagnostik zu definieren bedarf es weiterer großer, multizentrischer und prospektiver Studien.},
  subject      = {Ultraschall-Elastographie},
  language  = {de}
}
@phdthesis{MendesPereira2019,
  author    = {Mendes Pereira, Lenon},
  title     = {Morphological and Functional Ultrashort Echo Time (UTE) Magnetic Resonance Imaging of the Human Lung},
  doi       = {10.25972/OPUS-18317},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-183176},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2019},
  abstract  = {In this thesis, a 3D Ultrashort echo time (3D-UTE) sequence was introduced in the Self-gated Non-Contrast-Enhanced Functional Lung Imaging (SENCEFUL) framework. The sequence was developed and implemented on a 3 Tesla MR scanner. The 3D-UTE technique consisted of a nonselective RF pulse followed by a koosh ball quasi-random sampling order of the k-space. Measurements in free-breathing and without contrast agent were performed in healthy subjects and a patient with lung cancer. A gating technique, using a combination of different coils with high signal correlation, was evaluated in-vivo and compared with a manual approach of coil selection. The gating signal offered an estimation of the breathing motion during measurement and was used as a reference to segment the acquired data into different breathing phases. Gradient delays and trajectory errors were corrected during post-processing using the Gradient Impulse Response Function. Iterative SENSE was then applied to determine the fully sampled data. In order to eliminate signal changes caused by motion, a 3D image registration was employed, and the results were compared to a 2D image registration method. Ventilation was assessed in 3D and regionally quantified by monitoring the signal changes in the lung parenchyma. Finally, image quality and quantitative ventilation values were compared to the standard 2D-SENCEFUL technique. 3D-UTE, combined with an automatic gating technique and SENCEFUL MRI, offered ventilation maps with high spatial resolution and SNR. Compared to the 2D method, UTE-SENCEFUL greatly improved the clinical quality of the structural images and the visualization of the lung parenchyma. Through-plane motion, partial volume effects and ventilation artifacts were also reduced with a three-dimensional method for image registration. UTE-SENCEFUL was also able to quantify regional ventilation and presented similar results to previous studies.},
  subject      = {Kernspintomografie},
  language  = {en}
}
@phdthesis{KlinnertVlachopoulou2023,
  author    = {Klinnert Vlachopoulou, Cristina Maria},
  title     = {Comparison between Dual-Energy-CT perfusion imaging and perfusion-weighted SElf-gated Non-Contrast-Enhanced FUnctional MR imaging of the lung in patients with pulmonary artery embolism},
  doi       = {10.25972/OPUS-31303},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-313034},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2023},
  abstract  = {Pulmonary artery embolism (PE) is a common condition and an even more common clinical suspect. The computed tomography pulmonary angiogram (CTPA) is the main medical imaging tool used to diagnose a suspected case of PE. To gain a better impression of the effects of a PE on the perfusion and hence the gas exchange, a functional imaging method is beneficial. One approach for functional imaging using radiation exposure is the generation of color-coded iodine perfusion maps acquired by Dual-Energy Computed Tomography (DECT), which enable the detection of perfusion defects in the pulmonary parenchyma. In contrast to the existing approach of DECT with iodine color-coded maps, the SElf-gated Non-Contrast-Enhanced FUnctional Lung (SENCEFUL) MRI technique offers the possibility to interpret perfusion maps without any radiation exposure or application of contrast agents. The measurement in SENCEFUL MRI can be performed during conditions of free breathing and without electrocardiogram triggering. The purpose of this study was to determine whether PE can be diagnosed on the basis of visible perfusion defects in the perfusion maps of SENCEFUL MRI and in the iodine-coded maps of DECT and to compare the diagnostic performance of these methods. Both SENCEFUL-MRI and iodine distribution maps from DECT have been compared with the CTPA of ten patients with PE. Additionally, the functional images were compared with each other on a per-patient basis. The iodine perfusion maps of DECT had a sensitivity of 84.2 \% and specificity of 65.2 \% for the diagnosis of PE. The SENCEFUL technique in MRI showed a sensitivity of 78.9 \% and a specificity of 26.1 \%. When comparing the whole lung depicted in both series of functional images, the main perfusion defect location matched in four of ten patients (40 \%). In conclusion, this work found that DECT iodine maps have higher sensitivity and specificity in the diagnosis of pulmonary embolism compared with SENCEFUL MRI.},
  subject      = {Lungenembolie},
  language  = {en}
}