Detecting compartmental non-Gaussian diffusion with symmetrized double-PFG MRI

Area of Science:

• Magnetic Resonance Imaging (MRI)
• Biophysics
• Materials Science

Background:

• Diffusion in biological tissues and porous media is often non-Gaussian, complicating analysis with conventional NMR techniques.
• Heterogeneous materials exhibit multiple compartments, leading to apparent non-Gaussian diffusion signals.
• Existing methods struggle to differentiate true diffusion kurtosis from compartmental effects.

Purpose of the Study:

• To develop a novel NMR technique, symmetrized double pulsed field gradient (sd-PFG), to disentangle diffusion kurtosis from compartmental contributions.
• To enable unambiguous extraction of kurtosis and compartmental anisotropy from diffusion MRI signals.
• To improve the sensitivity and accuracy of diffusion measurements in complex media.

Main Methods:

• Implementation of symmetrized double pulsed field gradient (sd-PFG) NMR.
• Utilizing distinct angular modulation frequencies to separate signal decay components.
• Experimental validation of kurtosis measurement and comparison with theoretical predictions.

Main Results:

• sd-PFG successfully separates non-Gaussian diffusion contributions from multiple compartments.
• The method unambiguously extracts kurtosis from isotropic and anisotropic pore samples.
• Experimental results for diffusion kurtosis measurements align with theoretical expectations.

Conclusions:

• sd-PFG provides a robust method for identifying compartmental kurtosis in diffusion MRI.
• This technique can elucidate micro-structural changes related to kurtosis-based diagnostics.
• sd-PFG offers a novel source of contrast for enhanced tissue microstructure resolution.