Accelerated B+1 mapping and robust parallel transmit pulse design for heart and prostate imaging at 7 T

Egger N, Nagelstraßer S, Wildenberg S, Bitz A, Ruck L, Herrler J, Meixner CR, Kimmlingen R, Lanz T, Schmitter S, Uder M, Nagel AM (2024)

Publication Type: Journal article

Publication year: 2024

Journal

DOI: 10.1002/mrm.30185

Abstract

Purpose: To investigate the impact of reduced k-space sampling on (Formula presented.) mapping and the resulting impact on phase shimming and dynamic/universal parallel transmit (pTx) RF pulse design. Methods: Channel-wise 3D (Formula presented.) maps were measured at 7 T in 35 and 23 healthy subjects for the heart and prostate region, respectively. With these (Formula presented.) maps, universal phase shims optimizing homogeneity and (Formula presented.) efficiency were designed for heart and prostate imaging. In addition, universal 4kT-point pulses were designed for the heart. Subsequently, individual phase shims and individual 4kT-pulses were designed based on (Formula presented.) maps with different acceleration factors and tested on the original maps. The performance of the pulses was compared by evaluating their coefficients of variation (CoV), (Formula presented.) efficiencies and specific energy doses (SED). Furthermore, validation measurements were carried out for one heart and one prostate subject. Results: For both organs, the universal phase shims showed significantly higher (Formula presented.) efficiencies and lower CoVs compared to the vendor provided default shim, but could still be improved with individual phase shims based on accelerated (Formula presented.) maps (acquisition time = 30 s). In the heart, the universal 4kT-pulse achieved significantly lower CoVs than tailored phase shims. Tailored 4kT-pulses based on accelerated (Formula presented.) maps resulted in even further reduced CoVs or a 2.5-fold reduction in SED at the same CoVs as the universal 4kT-pulse. Conclusion: Accelerated (Formula presented.) maps can be used for the design of tailored pTx pulses for prostate and cardiac imaging at 7 T, which further improve homogeneity, (Formula presented.) efficiency, or SED compared to universal pulses.

Authors with CRIS profile

Involved external institutions

RAPID Biomedical GmbH Germany (DE) Physikalisch-Technische Bundesanstalt (PTB) Germany (DE) Fachhochschule Aachen - Aachen University of Applied Sciences Germany (DE)

How to cite

APA:

Egger, N., Nagelstraßer, S., Wildenberg, S., Bitz, A., Ruck, L., Herrler, J.,... Nagel, A.M. (2024). Accelerated B+1 mapping and robust parallel transmit pulse design for heart and prostate imaging at 7 T. Magnetic Resonance in Medicine. https://doi.org/10.1002/mrm.30185

MLA:

Egger, Nico, et al. "Accelerated B+1 mapping and robust parallel transmit pulse design for heart and prostate imaging at 7 T." Magnetic Resonance in Medicine (2024).

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