Dynamic magnetic resonance imaging with radial scanning: a post-acquisition keyhole approach |
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Authors: | R Lethmate H Ratiney F T A W Wajer Y Crémillieux D van Ormondt D Graveron-Demilly |
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Affiliation: | (1) Laboratoire de RMN, CNRS UMR 5012, Université Lyon I–CPE, 3 Rue Victor Grignard, 69616, Villeurbanne, France,;(2) Applied Physics Department, Delft University of Technology, Delft, The Netherlands, |
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Abstract: | A method—PA-keyhole—for 2D/3D dynamic magnetic resonance imaging with radial scanning is proposed. PA-keyhole exploits the
inherent strong oversampling in the center of k-space, which contains crucial temporal information regarding contrast evolution. The method is based on: (1) a rearrangement
of the temporal order of 2D/3D isotropic distributions of trajectories during the scan into subdistributions according to the desired time resolution, (2) a new post-acquisition keyhole approach based on the replacement of the central disk/sphere in k-space using data solely from a subdistribution, and (3) reconstruction of 2D/3D dynamic (time-resolved) images using 2D/3D-gridding
with Pipe's approach to the sampling density compensation and 2D/3D-IFFT. The scan time is not increased with respect to a
conventional 2D/3D radial scan of the same spatial resolution; in addition, one benefits from the dynamic information. The abilities of
PA-keyhole and the sliding window techniques to restore simulated dynamic contrast changes are compared. Results are shown
both for 2D and 3D dynamic imaging using experimental data. An application to in-vivo ventilation of rat lungs using hyperpolarized
helium is demonstrated.
Electronic Publication |
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Keywords: | 2D/3D dynamic MRI 3D isotropic radial sampling Keyhole Scan-time reduction Image reconstruction Gridding |
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