High-resolution whole-brain diffusion MRI at 7T using radiofrequency parallel transmission

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8 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)1857-1870
Number of pages14
JournalMagnetic resonance in medicine
Issue number5
StatePublished - Nov 2018

Bibliographical note

Funding Information:
This work was supported by NIH grants including U01 EB025144, P41 EB015894, and P30 NS076408

Publisher Copyright:
© 2018 International Society for Magnetic Resonance in Medicine


  • Human Connectome Project
  • diffusion MRI
  • high-field MRI
  • parallel transmission
  • simultaneous multi-slice

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