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- Title
Fully refocused multi-shot spatiotemporally encoded MRI: robust imaging in the presence of metallic implants.
- Authors
Ben-Eliezer, Noam; Solomon, Eddy; Harel, Elad; Nevo, Nava; Frydman, Lucio
- Abstract
Object: An approach has been recently introduced for acquiring arbitrary 2D NMR spectra or images in a single scan, based on the use of frequency-swept RF pulses for the sequential excitation and acquisition of the spins response. This spatiotemporal-encoding ( SPEN) approach enables a unique, voxel-by-voxel refocusing of all frequency shifts in the sample, for all instants throughout the data acquisition. The present study investigates the use of this full- refocusing aspect of SPEN- based imaging in the multi- shot MRI of objects, subject to sizable field inhomogeneities that complicate conventional imaging approaches. Materials and methods: 2D MRI experiments were performed at 7 T on phantoms and on mice in vivo, focusing on imaging in proximity to metallic objects. Fully refocused SPEN-based spin echo imaging sequences were implemented, using both Cartesian and back-projection trajectories, and compared with k-space encoded spin echo imaging schemes collected on identical samples under equal bandwidths and acquisition timing conditions. Results: In all cases assayed, the fully refocused spatiotemporally encoded experiments evidenced a ca. 50 % reduction in signal dephasing in the proximity of the metal, as compared to analogous results stemming from the k-space encoded spin echo counterparts. Conclusion: The results in this study suggest that SPEN-based acquisition schemes carry the potential to overcome strong field inhomogeneities, of the kind that currently preclude high-field, high-resolution tissue characterizations in the neighborhood of metallic implants.
- Subjects
MEDICAL imaging systems; BROADBAND communication systems; COMMUNITY relations; METALLURGICAL analysis; DETERMINATIVE mineralogy
- Publication
MAGMA: Magnetic Resonance Materials in Physics, Biology & Medicine, 2012, Vol 25, Issue 6, p433
- ISSN
0968-5243
- Publication type
Article
- DOI
10.1007/s10334-012-0318-7