TY - JOUR
T1 - High-resolution whole-brain diffusion MRI at 7T using radiofrequency parallel transmission
AU - Wu, Xiaoping
AU - Auerbach, Edward J.
AU - Vu, An T.
AU - Moeller, Steen
AU - Lenglet, Christophe
AU - Schmitter, Sebastian
AU - Van de Moortele, Pierre François
AU - Yacoub, Essa
AU - Uğurbil, Kâmil
N1 - Publisher Copyright:
© 2018 International Society for Magnetic Resonance in Medicine
PY - 2018/11
Y1 - 2018/11
N2 - Purpose: Investigating the utility of RF parallel transmission (pTx) for Human Connectome Project (HCP)-style whole-brain diffusion MRI (dMRI) data at 7 Tesla (7T). Methods: Healthy subjects were scanned in pTx and single-transmit (1Tx) modes. Multiband (MB), single-spoke pTx pulses were designed to image sagittal slices. HCP-style dMRI data (i.e., 1.05-mm resolutions, MB2, b-values = 1000/2000 s/mm2, 286 images and 40-min scan) and data with higher accelerations (MB3 and MB4) were acquired with pTx. Results: pTx significantly improved flip-angle detected signal uniformity across the brain, yielding ∼19% increase in temporal SNR (tSNR) averaged over the brain relative to 1Tx. This allowed significantly enhanced estimation of multiple fiber orientations (with ∼21% decrease in dispersion) in HCP-style 7T dMRI datasets. Additionally, pTx pulses achieved substantially lower power deposition, permitting higher accelerations, enabling collection of the same data in 2/3 and 1/2 the scan time or of more data in the same scan time. Conclusion: pTx provides a solution to two major limitations for slice-accelerated high-resolution whole-brain dMRI at 7T; it improves flip-angle uniformity, and enables higher slice acceleration relative to current state-of-the-art. As such, pTx provides significant advantages for rapid acquisition of high-quality, high-resolution truly whole-brain dMRI data.
AB - Purpose: Investigating the utility of RF parallel transmission (pTx) for Human Connectome Project (HCP)-style whole-brain diffusion MRI (dMRI) data at 7 Tesla (7T). Methods: Healthy subjects were scanned in pTx and single-transmit (1Tx) modes. Multiband (MB), single-spoke pTx pulses were designed to image sagittal slices. HCP-style dMRI data (i.e., 1.05-mm resolutions, MB2, b-values = 1000/2000 s/mm2, 286 images and 40-min scan) and data with higher accelerations (MB3 and MB4) were acquired with pTx. Results: pTx significantly improved flip-angle detected signal uniformity across the brain, yielding ∼19% increase in temporal SNR (tSNR) averaged over the brain relative to 1Tx. This allowed significantly enhanced estimation of multiple fiber orientations (with ∼21% decrease in dispersion) in HCP-style 7T dMRI datasets. Additionally, pTx pulses achieved substantially lower power deposition, permitting higher accelerations, enabling collection of the same data in 2/3 and 1/2 the scan time or of more data in the same scan time. Conclusion: pTx provides a solution to two major limitations for slice-accelerated high-resolution whole-brain dMRI at 7T; it improves flip-angle uniformity, and enables higher slice acceleration relative to current state-of-the-art. As such, pTx provides significant advantages for rapid acquisition of high-quality, high-resolution truly whole-brain dMRI data.
KW - Human Connectome Project
KW - diffusion MRI
KW - high-field MRI
KW - parallel transmission
KW - simultaneous multi-slice
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U2 - 10.1002/mrm.27189
DO - 10.1002/mrm.27189
M3 - Article
C2 - 29603381
AN - SCOPUS:85048747190
SN - 0740-3194
VL - 80
SP - 1857
EP - 1870
JO - Magnetic resonance in medicine
JF - Magnetic resonance in medicine
IS - 5
ER -