Multiple q-shell diffusion propagator imaging.

Area of Science:

• Neuroimaging
• Diffusion MRI Physics
• Biomedical Engineering

Background:

• High angular resolution diffusion imaging (HARDI) methods reconstruct orientation distribution functions (ODFs) from diffusion MRI data.
• Current HARDI techniques often rely on single-shell (one b-value) acquisitions, limiting microstructure information to angular properties.
• Ensemble average propagator (EAP) provides richer tissue microstructure insights by incorporating radial diffusion information.

Purpose of the Study:

• To present a novel analytical technique for ensemble average propagator (EAP) reconstruction from multiple q-shell diffusion MRI acquisitions.
• To enable more comprehensive tissue microstructure characterization by leveraging both angular and radial diffusion information.
• To develop a computationally efficient and robust EAP reconstruction method.

Main Methods:

• Developed an analytical EAP reconstruction technique based on Laplace equation estimation across multiple q-shells.
• Simplified the Fourier integral relating diffusion signal and EAP for linear and compact reconstruction.
• Validated the method using ex vivo phantom datasets and in vivo human brain data.

Main Results:

• The proposed method successfully reconstructs EAP from multiple q-shell data.
• Validation on ex vivo phantoms confirmed accurate diffusion signal estimation and EAP reconstruction.
• In vivo human brain imaging demonstrated robust EAP reconstruction with fewer measurements compared to diffusion spectrum imaging (DSI).

Conclusions:

• The novel analytical EAP reconstruction technique is effective for multiple q-shell diffusion MRI.
• This method provides a robust and efficient way to investigate complex tissue microstructures.
• mq-DPI (multiple q-shell diffusion propagator imaging) offers promising avenues for advanced q-space sampling and microstructure analysis.