Tailored and universal parallel transmit broadband pulses for homogeneous 3D excitation of the human heart at 7T

To research and evaluate the performance of broadband tailored kT-point pulses (TP) and universal pulses (UP) for homogeneous excitation of the human heart at 7T. Relative 3D -maps of the thorax were acquired from 29 healthy volunteers. TP and UP were designed using the small-tip-angle approximation...

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Bibliographic Details
Published in:Magnetic resonance in medicine 2024-08, Vol.92 (2), p.730-740
Main Authors: Aigner, Christoph Stefan, Dietrich-Conzelmann, Sebastian, Lutz, Max, Krüger, Felix, Schmitter, Sebastian
Format: Article
Language:English
Subjects:
Adult
Algorithms
Broadband
Coefficient of variation
Excitation
Female
Frequency ranges
Healthy Volunteers
Heart
Heart - diagnostic imaging
Homogeneity
Humans
Imaging, Three-Dimensional
Magnetic Resonance Imaging
Male
Performance evaluation
Reproducibility of Results
Thorax
Young Adult
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Summary:To research and evaluate the performance of broadband tailored kT-point pulses (TP) and universal pulses (UP) for homogeneous excitation of the human heart at 7T. Relative 3D -maps of the thorax were acquired from 29 healthy volunteers. TP and UP were designed using the small-tip-angle approximation for a different composition of up to seven resonance frequencies. TP were computed for each of the 29 -maps, and UPs were calculated using 22 -maps and tested in seven testcases. The performance of the pulses was analyzed using the coefficient of variation (CV) in the 3D heart volumes. The 3D gradient-echo (GRE) scans were acquired for the seven testcases to qualitatively validate the -predictions. Single- and double-frequency optimized pulses achieved homogeneity in flip angle (FA) for the frequencies they were optimized for, while the broadband pulses achieved uniformity in FA across a 1300 Hz frequency range. Broadband TP and UP can be used for homogeneous excitation of the heart volume across a 1300 Hz frequency range, including the water and the main six fat peaks, or with longer pulse durations and higher FAs for a smaller transmit bandwidth. Moreover, despite large inter-volunteer variations, broadband UP can be used for calibration-free 3D heart FA homogenization in time-critical situations.
ISSN:0740-3194
1522-2594
1522-2594
DOI:10.1002/mrm.30072