Efficient whole-brain tract-specific T₁ mapping at 3T with slice-shuffled inversion-recovery diffusion-weighted...

Area of Science:

• Neuroimaging
• Diffusion MRI
• Quantitative MRI

Background:

• White matter voxels contain complex fiber populations with varying orientations and myelination.
• Conventional T1 mapping provides averaged T1 values, masking tract-specific information.
• Inversion-recovery diffusion-weighted imaging (IR-DWI) can resolve multiple tract T1 values but is time-intensive.

Purpose of the Study:

• To demonstrate whole-brain tract-specific T1 mapping using simultaneous multi-slice slice-shuffled IR-DWI at 3T.
• To overcome the long scan times associated with conventional IR-DWI.
• To enable improved microstructural characterization of white matter tracts.

Main Methods:

• Simulations were performed to assess the accuracy and precision of a crossing fiber IR-DWI signal model.
• The proposed sequence and model were validated using a phantom with varying T1 values (gadolinium-doped asparagus).
• In-vivo testing was conducted in two human subjects.

Main Results:

• Simulations showed tract-specific T1 values estimated within 5% of nominal values.
• Subvoxel crossing fibers in the phantom demonstrated resolved tract-specific T1 values.
• In human subjects, T1 values were resolved in known crossing tracts (cingulum/corpus callosum and corticospinal tract/pontine fibers), areas with reported myelination differences.

Conclusions:

• Whole-brain tract-specific T1 mapping is feasible with simultaneous multi-slice slice-shuffled IR-DWI at 3T.
• This technique offers a significant reduction in scan time compared to conventional methods.
• The method holds promise for enhancing the microstructural characterization of white matter tracts in neurodevelopmental, aging, and demyelinating disorders.