Abstract:
:Parallel excitation is being studied intensively for applications in MR imaging and in particular for selecting arbitrary shapes as regions of interest. In this work, parallel excitation was applied to arbitrarily shaped voxel selection in spectroscopy and investigated for different excitation k-space trajectories (radial, rectilinear, and spiral) and acceleration factors. Each trajectory was segmented into multiple excitations to increase the overall bandwidth during target selection. Acceleration by parallel excitation was used to decrease the number of segments. Evaluation of spatial and spectral localization of the target of interest was performed in simulation and phantom experiments, and was compared with the point resolved spectroscopy (PRESS) experiment with standard voxels. The selective excitation experiments demonstrated excellent spatial localization and a broad frequency response, although PRESS was superior in direct comparisons with respect to signal-to-noise ratio (SNR) and outer volume suppression. Extensive SNR variation was observed dependent on trajectory (8%-90%), with the preferred radial case producing approximately 40%-60% SNR of the PRESS case. Accelerated trajectories at R = 4 provided comparable artifact signal and target excitation accuracy compared with their nonaccelerated counterparts; however, further acceleration (R = 8) resulted in increased artifact (33% increase at R = 8).
journal_name
Magn Reson Medjournal_title
Magnetic resonance in medicineauthors
Snyder J,Haas M,Hennig J,Zaitsev Mdoi
10.1002/mrm.23018subject
Has Abstractpub_date
2012-02-01 00:00:00pages
300-9issue
2eissn
0740-3194issn
1522-2594journal_volume
67pub_type
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