Phantomentwicklung und Einführung einer systematischen Qualitätssicherung bei multizentrischen Magnetresonanztomographie-Untersuchungen
In dieser Arbeit wird die systematische Einführung einer Qualitätssicherung (QA) für multizentrische MRT-Untersuchungen beschrieben. Anhand von Agarosegel-Phantomen wird eine automatisierte QA-Analyse aufgesetzt, die die Untersuchung des SNR-Verhaltens, der Signalhomogenität, des Ghosting-Grades und...
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In this doctoral thesis, the systematic implementation of quality assurance(QA) for multicenter MRI studies is described. An automated QA analysis procedure based on agar gel phantoms, allowing for evaluation of SNR, image uniformity, ghosting and temporal stability of fMRI measurements, is presented. Manufacturing of agar gel phantoms was optimized towards long-term stability (> 8 months) without addition of toxical substances to the phantoms. Considering the requirements for regular use, simple and safe handling procedures of the phantoms concerning shipping, measurements and disposal is essential. The effectiveness of the QA procedure and analysis software has been proven successfully within the CBASP study. Additionally, QA measurements using the ACR MRI phantom (developed by the American College of Radiology for accreditation) were performed on different scanner sites. The manual evaluation of test parameters proposed by the American College of Radiology was converted in an automated analysis procedure. Special phantoms were developed for Diffusion Tensor Imaging and manufacturing of these phantoms was optimized for the use as multicentric QA test objects. Advantages of carbomer gels as new phantom material for embedding DTI fibre objects were demonstrated. This offers new prospects for the described QA analysis based on agar gel phantoms.