The Bloch-Siegert (B-S) B1 (+) mapping technique is a fast, phase-based method that is highly SAR limited especially at 7T, necessitating the use of long repetition times. Spiral and echo-planar readouts were incorporated in a gradient-echo based B-S sequence to reduce specific absoprtion rate (SAR) and improve its scan efficiency. A novel, numerically optimized 4 ms B-S off-resonant pulse at + 1960 Hz was used to increase sensitivity and further reduce SAR compared with the conventional 6 ms Fermi B-S pulse. Using echo-planar and spiral readouts, scan time reductions of 8-16 were achieved. By reducing the B-S pulse width by a factor of 1.5, SAR was reduced by a factor of 1.5 and overall sensitivity was increased by a factor of 1.33 due to the nearly halved resonance offset of the new B-S pulse. This was validated on phantoms and volunteers at 7 T.
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http://dx.doi.org/10.1002/mrm.24599 | DOI Listing |
Eur J Appl Physiol
December 2024
National Centre for Sport and Exercise Medicine, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.
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View Article and Find Full Text PDFMicrobiol Spectr
January 2025
Department of Clinical Laboratory and Biomedical Sciences, Laboratory of Medical Microbiology and Microbiome, Division of Health Sciences, Osaka University Graduate School of Medicine, Suita, Osaka, Japan.
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Clinical Cardiology, St. George's University of London, London, United Kingdom (A.J.C.).
Biomedicines
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Department of Cardiology, Angiology, and Intensive Care Medicine, University Hospital, Philipps University of Marburg, Baldinger Str., 35043 Marburg, Germany.
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