Converting Multi-Shell and Diffusion Spectrum Imaging to High Angular Resolution Diffusion Imaging.

Area of Science:

• Neuroimaging
• Biomedical Engineering
• Radiology

Background:

• Diffusion MRI techniques like multi-shell and Diffusion Spectrum Imaging (DSI) are increasingly used in research.
• Single-shell acquisitions, including Diffusion Tensor Imaging (DTI) and High Angular Resolution Diffusion Imaging (HARDI), are still common in practice.

Purpose of the Study:

• To evaluate the conversion flexibility of multi-shell and DSI data to HARDI.
• To assess the fidelity of converted HARDI data compared to directly acquired HARDI.

Main Methods:

• Acquired multi-shell and DSI data on a phantom and in vivo human subjects.
• Converted multi-shell and DSI data to HARDI.
• Analyzed diffusion signals, anisotropy, diffusivity, fiber orientations, connectivity matrices, and network measures.

Main Results:

• Converted HARDI data showed high correlation (0.8-0.9) with original HARDI for diffusion signals, anisotropy, diffusivity, and connectivity matrices.
• Average angular error between converted and original HARDI was 20.7° in voxels with SNR > 5.
• Network topology measures differed by <2%, and average nodal measures by 4-7%.

Conclusions:

• Multi-shell and DSI acquisitions can be converted to single-shell HARDI with high fidelity.
• This conversion capability supports the use of multi-shell and DSI as preferred diffusion MRI acquisition schemes over HARDI.