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Real-time MRI: recent advances using radial FLASH

Martin Uecker, Shuo Zhang, Dirk Voit, Klaus Dietmar, Merboldt and Jens Frahm

Recent advances in real-time MRI result in high-quality images with acquisition times of only approximately 30 ms. The technique employs a fast low-angle shot sequence with proton density, T1 or T2/T1 contrast and radial data encoding for motion robustness. High temporal resolution is achieved by an up to 20-fold undersampling of the radial data. An iterative reconstruction algorithm estimates the image as the solution of a nonlinear inverse problem and ensures image fidelity by temporal regularization, which exploits the temporal continuity of successive frames during dynamic imaging. Preliminary real-time examinations at a field strength of 3T range from joint dynamics, speaking and swallowing to the 3D localization of objects in space. In particular, real-time MRI largely facilitates assessments of cardiovascular function and quantitative blood flow. Taken together, advanced real-time MRI methods allow for hitherto inaccessible studies, lead to more robust and shorter examinations, improve patient comfort and offer new diagnostic opportunities.