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- Title
Tailored and universal parallel transmit broadband pulses for homogeneous 3D excitation of the human heart at 7T.
- Authors
Aigner, Christoph Stefan; Dietrich‐Conzelmann, Sebastian; Lutz, Max; Krüger, Felix; Schmitter, Sebastian
- Abstract
Purpose: 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. Methods: Relative 3D B1+$$ {\mathrm{B}}_1^{+} $$‐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 B1+$$ {\mathrm{B}}_1^{+} $$‐maps, and UPs were calculated using 22 B1+$$ {\mathrm{B}}_1^{+} $$‐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 B1+$$ {\mathrm{B}}_1^{+} $$‐predictions. Results: 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. Conclusion: 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.
- Subjects
HEART; WATER-pipes; HUMAN beings
- Publication
Magnetic Resonance in Medicine, 2024, Vol 92, Issue 2, p730
- ISSN
0740-3194
- Publication type
Article
- DOI
10.1002/mrm.30072