Optimization of Cardiac-MR Protocols

Feasibility, Normal Values, Protocol Optimization, Sequence Optimization

The aim of the present study is the optimization of various magnetic resonance (MR) investigation protocols of the heart and the lung without contrast agent application as well as the generation of normal values from cardiac MR images. One of the main problems in cardiac MR investigations is the strong dependence of the achieved image quality on optimal settings of sequence parameters and anatomical and physiological situations with special emphasis on phase-contrast imaging and other cine-techniques.

Time optimized and well organized MR protocols for the cardiac and lung investigations are evaluated on normal subjects with special respect to following topics: 1. Localization: Definition of standardized anatomic imaging planes with special respect to the right ventricle. 2. Morphological imaging: Optimization of spin-echo and gradient-echo sequences for various heart frequencies and breath-hold abilities. Investigation of the effect of various preparation pulses. Optimization of the signal-to-noise ratio for morphological cardiac imaging. Evaluation and optimization of various breathing and breath-hold (with and without navigator) ECG and pulse triggered sequences. 3. Cardiac and lung function: Optimization of gradient-echo sequences for various heart frequencies and breath-hold abilities. Evaluation of pulse-triggered function analysis and optimization of free breathing protocols. Optimization of tagging techniques. Evaluation of the pulsatile flow in lung vessels. Acquisition of age depended normal data of cardiac and lung function. 4. Coronary imaging: Definition of standardized anatomic imaging planes to monitor coronary arteries (single oblique, volume targeted). Optimization of acquisition window with respect to various heart frequencies. Evaluation of the influence of the position of the navigator and tracking factor on image quality. Optimization of a pulse triggered protocol. Evaluation of black-blood coronary imaging and visualization of the lumen and wall of coronary arteries. 5. Phase contrast techniques: Optimization of imaging planes, time resolution and spatial resolution of flow measurements in the heart, in the vessels around the heart, lung vessels and coronary arteries. Evaluation of retrospective and prospective gating with respect to the heart frequency. Evaluation of normal values in 1-dimensional, 2-dimensional and 3-dimensional time resolved flow measurements. 6. Single-Shot Imaging: Evaluation of signal intensity and stability of single shot techniques with and without preparation pulses. Optimization of real-time image acquisition. 7. Parallel acquisition and breath-hold time optimization: Evaluation of impact of echo-sharing and parallel acquisition on image quality. Optimization of short-breath-hold protocols.

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Austria