Time-efficient and flexible design of optimized multishell HARDI diffusion.

Area of Science:

• Magnetic Resonance Imaging
• Neuroimaging
• Biomedical Engineering

Background:

• Diffusion MRI is sensitive to subject motion, increasing data loss risk with longer scans.
• Optimizing acquisition is key for advanced diffusion MRI, especially in vulnerable populations like neonates.
• Current methods may lead to suboptimal choices due to hardware constraints.

Purpose of the Study:

• To develop a maximally time-efficient and flexible diffusion MRI acquisition capability.
• To build in robustness against partially acquired or interrupted scans.
• To create a framework applicable to various research domains, including the developing Human Connectome Project.

Main Methods:

• Developed a framework with complete flexibility in diffusion space sampling and phase-encode direction.
• Incorporated motion robustness, internal consistency checks, and hardware limit considerations.
• Implemented split-diffusion-gradient preparation, multiband acceleration, and a restart capacity.

Main Results:

• Explored parameter choices for high angular resolution diffusion imaging (HARDI) sampling.
• Acquired a 20-minute, 300-volume multishell diffusion MRI protocol in over 400 neonates for the developing Human Connectome Project.
• Designed an optimal high-resolution (1.2 x 1.2 mm^2) two-shell acquisition with 54 volumes using a split-gradient design.

Conclusions:

• The framework offers flexibility for time-efficient, motion-robust diffusion MRI acquisitions.
• It accounts for hardware constraints to prevent suboptimal acquisition choices.
• The developed system supports advanced neuroimaging research, particularly in pediatric studies.