Journal Article

DZNE-2026-01162

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Whole-Brain Diffusion MRI at 7T With Universal Multiband GRAPE pTx Pulses.

Laufenberg, M. (First author)DZNE* ; Löwen, D.DZNE* ; Ferreira, M.DZNE* ; Boulant, N. ; Faber, J.DZNE* ; Stöcker, T. (Last author)DZNE*

2027
Wiley-Liss New York, NY [u.a.]

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Please use a persistent id in citations: doi:10.1002/mrm.70588

Abstract: To improve signal strength and homogeneity of whole-brain diffusion-weighted imaging (DWI) at 7T.Universal multiband excitation and refocusing pulses were optimized with the gradient ascent pulse engineering (GRAPE) algorithm across a database of B 1 + and B 0 maps obtained from 20 subjects. Slice-selective multiband pulses were optimized in a two-step optimization for transverse and sagittal slice orientations. The optimized pTx pulses were compared to standard circular polarized (CP) pulses in five subjects using a multiband diffusion-weighted EPI sequence at 1.5 mm isotropic resolution and in one subject at 1.05 mm resolution. The evaluation included Bloch simulations, flip angle mapping, SNR analysis, and diffusion model fitting (DTI and NODDI).Both GRAPE pulse sets with transverse and sagittal slice orientation improved signal homogeneity and SNR compared to CP pulses across all subjects and head sizes, with particularly high gains in the cerebellum. Sagittal GRAPE pulses yielded the highest mean signal and lowest standard deviation across the brain, while transverse GRAPE pulses provided better cerebellar signal at the cost of signal loss in off-resonant frontal and temporal regions of large heads. The improved signal translated into more reliable DTI and NODDI fitting, especially in the cerebellum.Universal multiband GRAPE pTx pulses substantially improve signal homogeneity and SNR in whole-brain DWI at 7T, enabling more reliable diffusion microstructure mapping, particularly in the cerebellum.

Keyword(s): Humans (MeSH) ; Diffusion Magnetic Resonance Imaging: methods (MeSH) ; Algorithms (MeSH) ; Brain: diagnostic imaging (MeSH) ; Signal-To-Noise Ratio (MeSH) ; Image Processing, Computer-Assisted: methods (MeSH) ; Male (MeSH) ; Adult (MeSH) ; Female (MeSH) ; Echo-Planar Imaging (MeSH) ; Computer Simulation (MeSH) ; diffusion MRI ; parallel transmission ; ultra‐high field

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Contributing Institute(s):

1. MR Physics (AG Stöcker)
2. Clinical Neuroimaging (AG Radbruch)
3. Clinical Research Coordination (Clinical Research (Bonn))

Research Program(s):

1. 354 - Disease Prevention and Healthy Aging (POF4-354) (POF4-354)
2. 353 - Clinical and Health Care Research (POF4-353) (POF4-353)

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Database coverage:
; BIOSIS Previews ; Biological Abstracts ; Clarivate Analytics Master Journal List ; Current Contents - Clinical Medicine ; Current Contents - Life Sciences ; DEAL Wiley ; Essential Science Indicators ; IF < 5 ; JCR ; Nationallizenz ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

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