A time-efficient acquisition protocol for multipurpose diffusion-weighted microstructural imaging at 7 Tesla.

Area of Science:

• Neuroimaging
• Magnetic Resonance Imaging (MRI)
• Diffusion-Weighted Imaging (DWI)

Background:

• Diffusion-weighted MRI techniques offer valuable neuroanatomical insights but often require lengthy acquisition times.
• Existing methods have varying optimal designs, limiting comprehensive analysis, especially under time constraints.

Purpose of the Study:

• To develop and validate a time-efficient diffusion-weighted MRI acquisition scheme at 7 Tesla.
• To enable comprehensive microstructural imaging of the brain within a reduced timeframe for researchers and clinicians.

Main Methods:

• Testing b-values from 700 to 3000 s/mm² with varying angular diffusion-encoding samples.
• Comparing acquisition protocols against a data-driven "gold standard" for validation.

Main Results:

• A recommended protocol uses b-values of 1000 and 2500 s/mm² with 25 and 50 uniformly distributed samples across two shells.
• Several other protocols demonstrated high correlation with the gold standard when fitting microstructural models.

Conclusions:

• Minimum acquisition requirements were estimated for diffusion tensor imaging, higher angular resolution diffusion-weighted imaging, neurite orientation dispersion and density imaging, and white matter tract integrity.
• The optimized protocol achieves isotropic 1.8 mm resolution across the whole brain in under 11 minutes.