White matter biomarkers from fast protocols using axially symmetric diffusion kurtosis imaging

Area of Science:

• Neuroimaging
• Biomarkers
• Brain Microstructure Analysis

Background:

• White matter tract integrity (WMTI) is crucial for characterizing brain microstructure, particularly in aligned fiber bundles.
• Current WMTI methods, often relying on conventional diffusion kurtosis imaging (DKI), are data-intensive, limiting routine clinical application and high-resolution validation studies.
• There is a need for a less data-intensive WMTI approach to facilitate both preclinical research and clinical translation.

Purpose of the Study:

• To evaluate the feasibility of WMTI using a less data-intensive, axially symmetric DKI model.
• To compare WMTI parameters derived from axially symmetric DKI with those from conventional DKI.
• To assess the potential of this faster WMTI approach for preclinical and clinical applications.

Main Methods:

• WMTI parameters were calculated analytically from axially symmetric DKI and compared with those from conventional DKI.
• Numerical simulations and data from fixed rat spinal cord, in vivo human brains, and in vivo rat brains were utilized.
• The proposed method used sparse data sets (19 images) compared to traditional DKI protocols (60+ images).

Main Results:

• Analytical WMTI based on axially symmetric DKI with sparse data sets strongly correlated with WMTI metrics derived from traditional, data-rich DKI protocols.
• The technique demonstrated preclinical potential in vivo rat brain imaging, achieving 300 μm isotropic resolution with whole-brain coverage in a 1-hour acquisition.
• WMTI parameter estimation involves a duality with two solution branches, both of which were analyzed.

Conclusions:

• Fast WMTI based on axially symmetric DKI provides reliable metrics comparable to conventional DKI, despite reduced data requirements.
• This optimized WMTI approach holds significant promise for accelerating preclinical research and enabling clinical evaluation of white matter injuries and neurological disorders.
• The method's efficiency may pave the way for more widespread use of WMTI in clinical settings.