ALBERT

Description: 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. Content Type Journal Article Category Research Article Pages 1-10 DOI 10.1007/s10334-012-0318-7 Authors Noam Ben-Eliezer, Chemical Physics Department, Weizmann Institute of Science, 76100 Rehovot, Israel Eddy Solomon, Chemical Physics Department, Weizmann Institute of Science, 76100 Rehovot, Israel Elad Harel, Chemistry Department, Northwestern University, Evanston, IL 60201, USA Nava Nevo, Biological Regulation Department, Weizmann Institute of Science, 76100 Rehovot, Israel Lucio Frydman, Chemical Physics Department, Weizmann Institute of Science, 76100 Rehovot, Israel Journal Magnetic Resonance Materials in Physics, Biology and Medicine Online ISSN 1352-8661 Print ISSN 0968-5243