Fast diffusion imaging with high angular resolution.

Area of Science:

• Neuroimaging
• Diffusion MRI
• Medical Physics

Background:

• High angular resolution diffusion imaging (HARDI) reveals nerve bundle architecture but faces limitations due to long scan times and geometric distortions from echo planar imaging (EPI).
• Clinical integration of HARDI is hindered by these challenges, necessitating faster and more accurate imaging techniques.

Purpose of the Study:

• To develop and evaluate a novel, accelerated imaging method for high angular resolution diffusion imaging (HARDI).
• To significantly reduce scan duration and minimize geometric distortions in HARDI acquisitions.

Main Methods:

• The proposed method combines accelerated multishot diffusion imaging (AMDI), multiplexed sensitivity encoding (MUSE), and crossing fiber angular resolution of intravoxel structure (CFARI).
• A multishot EPI sequence was employed for improved geometrical fidelity, alongside k-space and diffusion sampling acceleration.
• The technique incorporates regularization and self-navigation for motion correction, with whole-brain acquisitions performed on seven volunteers.

Main Results:

• Achieved average similarity of microstructural orientations above 85% between undersampled and fully sampled datasets.
• Reduced scan times to below 5 minutes for whole-brain HARDI acquisitions.
• Demonstrated up to 2.7-fold scan time acceleration and four-fold reduction in spatial distortions.

Conclusions:

• The developed imaging strategy effectively generates HARDI results with good geometrical fidelity and reduced scan duration.
• This approach shows promise in transitioning HARDI from a research tool to a practical clinical application.
• The method facilitates the integration of advanced diffusion imaging techniques into routine clinical practice.