B1+ inhomogeneity mitigation in CEST using parallel transmission

Tse, Desmond H.Y., da Silva, Nuno Andre, Poser, Benedikt A. and Shah, N. Jon (2017) B1+ inhomogeneity mitigation in CEST using parallel transmission. Magnetic Resonance in Medicine, . doi:10.1002/mrm.26624


Author Tse, Desmond H.Y.
da Silva, Nuno Andre
Poser, Benedikt A.
Shah, N. Jon
Title B1+ inhomogeneity mitigation in CEST using parallel transmission
Formatted title
B1+ inhomogeneity mitigation in CEST using parallel transmission
Journal name Magnetic Resonance in Medicine   Check publisher's open access policy
ISSN 0740-3194
1522-2594
Publication date 2017-02-28
Year available 2017
Sub-type Article (original research)
DOI 10.1002/mrm.26624
Open Access Status Not yet assessed
Total pages 10
Place of publication Hoboken, NJ, United States
Publisher John Wiley & Sons
Collection year 2018
Language eng
Formatted abstract
Purpose
In order to benefit from the increased spectral bandwidth at ultrahigh field (UHF), the use of parallel transmission (pTx) to mitigate flip-angle inhomogeneity in chemical exchange saturation transfer (CEST) imaging is investigated.

Theory and Methods
A pTx basis pulse is homogenised by magnitude least-squares (MLS) optimization and expanded to form a frequency-selective saturation pulse for CEST. The pTx saturation pulse was simulated with a three-pool Bloch-McConnell equation to evaluate the impact of pTx on CEST contrast. In vivo CEST imaging performance (7 T) of the pTx saturation pulse and the standard Gaussian saturation in circularly polarized mode were compared. Two-spokes pTx homogeneous excitation was used in all in vivo experiments to ensure fair comparison of the two saturation pulses. Magnetization transfer ratio and inverse Z-spectrum analyses were used as metrics in evaluating the data from 3 healthy volunteers.

Results
Bloch-McConnell simulations showed that side bands of the pTx saturation pulse at ±20 ppm did not affect any CEST contrast. Improved homogeneity in contrasts and relaxation-compensated CEST metrics were observed in our in vivo data when the pTx saturation pulse was used.

Conclusion
A pTx-based pulsed CEST presaturation scheme is proposed and validated by simulations and 7T in vivo imaging. Magn Reson Med, 2017. © 2017 International Society for Magnetic Resonance in Medicine.
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: HERDC Pre-Audit
Centre for Advanced Imaging Publications
 
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