Full utilization of conjugate symmetry: combining virtual conjugate coil reconstruction with partial Fourier imaging for g-factor reduction in accelerated MRI.

Autor: Kettinger AO; Brain Imaging Centre, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary.; Department of Nuclear Techniques, Budapest University of Technology and Economics, Budapest, Hungary.; Siemens Healthcare GmbH, Erlangen, Germany., Setsompop K; Athinoula A. Martinos Center for Biomedical Imaging, Charlestown, Massachusetts.; Department of Radiology, Harvard Medical School, Boston, Massachusetts.; Harvard-MIT Health Sciences and Technology, MIT, Cambridge, Massachusetts., Kannengiesser SAR; Siemens Healthcare GmbH, Erlangen, Germany., Breuer FA; Magnetic Resonance and X-ray Imaging Department, Fraunhofer Development Center X-ray Technology (EZRT), Würzburg, Germany., Vidnyanszky Z; Brain Imaging Centre, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary., Blaimer M; Magnetic Resonance and X-ray Imaging Department, Fraunhofer Development Center X-ray Technology (EZRT), Würzburg, Germany.
Jazyk: angličtina
Zdroj: Magnetic resonance in medicine [Magn Reson Med] 2019 Sep; Vol. 82 (3), pp. 1073-1090. Date of Electronic Publication: 2019 May 13.
DOI: 10.1002/mrm.27799
Abstrakt: Purpose: In this study we propose a method to combine the parallel virtual conjugate coil (VCC) reconstruction with partial Fourier (PF) acquisition to improve reconstruction conditioning and reduce noise amplification in accelerated MRI where PF is used.
Methods: Accelerated measurements are reconstructed in k-space by GRAPPA, with a VCC reconstruction kernel trained and applied in the central, symmetrically sampled part of k-space, while standard reconstruction is performed on the asymmetrically sampled periphery. The two reconstructed regions are merged to form a full reconstructed dataset, followed by PF reconstruction. The method is tested in vivo using T1-weighted spin-echo and T2*-weighted gradient-echo echo planar imaging (EPI) sequences, using both in-plane and simultaneous multislice (SMS) acceleration, at 1.5T and 3T field strengths. Noise amplification is estimated with theoretical calculations and pseudo-multiple-replica computations, for different PF factors, using zero-filling, homodyne, and projection onto convex sets (POCS) PF reconstruction.
Results: Depending on the PF algorithm and the inherent benefit of VCC reconstruction without PF, approximately 35% to 80%, 15% to 60%, and 5% to 30% of that intrinsic SNR gain can be retained for PF factors 7/8, 6/8, and 5/8, respectively, by including the VCC signals in the reconstruction. Compared with VCC-reconstructed acquisitions of higher acceleration, without PF, but having the same net acceleration, the combined method can provide a higher SNR if the inherent benefit of VCC is low or moderate.
Conclusion: The proposed technique enables the partial application of VCC reconstruction to measurements with PF using either in-plane or SMS acceleration, and therefore can reduce the noise amplification of such acquisitions.
(© 2019 International Society for Magnetic Resonance in Medicine.)
Databáze: MEDLINE
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