Meixner C, Eisen C, Schmitter S, Müller M, Herrler J, Hensel B, Dörfler A, Uder M, Nagel AM (2021)
Publication Type: Journal article
Publication year: 2021
DOI: 10.1002/mrm.28982
Purpose: To improve pseudo-continuous arterial spin labeling (pcASL) at 7T by exploiting a hybrid homogeneity- and efficiency-optimized (Formula presented.) -shim with adapted gradient strength as well as background suppression. Methods: The following three experiments were performed at 7T, each employing five volunteers: (1) A hybrid (ie, homogeneity-efficiency optimized) (Formula presented.) -shim was introduced and evaluated for variable-rate selective excitation pcASL labeling. Therefore, (Formula presented.) -maps in the V3 segment and time-of-flight images were acquired to identify the feeding arteries. For validation, a gradient-echo sequence was applied in circular polarized (CP) mode and with the hybrid (Formula presented.) -shim. Additionally, the gray matter (temporal) signal-to-noise ratio (tSNR) in pcASL perfusion images was evaluated. (2) Bloch simulations for the pcASL labeling were conducted and validated experimentally, with a focus on the slice-selective gradients. (3) Background suppression was added to the (Formula presented.) -shimmed, gradient-adapted 7T sequence and this was then compared to a matched sequence at 3T. Results: The (Formula presented.) -shim improved the signal within the labeling plane (23.6%) and the SNR/tSNR increased (+11%/+11%) compared to its value in CP mode; however, the increase was not significant. In accordance with the simulations, the adapted gradients increased the tSNR (35%) and SNR (45%) significantly. Background suppression further improved the perfusion images at 7T, and this protocol performed as well as a resolution-matched protocol at 3T. Conclusion: The combination of the proposed hybrid (Formula presented.) -phase-shim with the adapted slice-selective gradients and background suppression shows great potential for improved pcASL labeling under suboptimal (Formula presented.) conditions at 7T.
APA:
Meixner, C., Eisen, C., Schmitter, S., Müller, M., Herrler, J., Hensel, B.,... Nagel, A.M. (2021). Hybrid B1+-shimming and gradient adaptions for improved pseudo-continuous arterial spin labeling at 7 Tesla. Magnetic Resonance in Medicine. https://doi.org/10.1002/mrm.28982
MLA:
Meixner, Christian, et al. "Hybrid B1+-shimming and gradient adaptions for improved pseudo-continuous arterial spin labeling at 7 Tesla." Magnetic Resonance in Medicine (2021).
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