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Enabling Complex Fibre Geometries Using 3D Printed Axon-Mimetic Phantoms
Tristan K Kuehn1,2, Farah N Mushtaha2, Ali R Khan1,2,3,4,5
1Centre for Functional and Metabolic Mapping, Robarts Research Institute, Western University, London, ON, Canada.
Frontiers in Neuroscience
|April 25, 2022
Summary
3D-printed axon-mimetic phantoms help evaluate diffusion MRI models by simulating complex fibre orientations. Bingham-NODDI best characterized fibre dispersion, offering insights into diffusion MRI model performance.
Area of Science:
- Neuroimaging
- Biomedical Engineering
- Medical Physics
Background:
- Diffusion MRI models are crucial for understanding brain microstructure.
- Characterizing complex fibre orientations, like crossings and bending, remains a challenge for these models.
- Developing accurate phantoms is essential for validating diffusion MRI techniques.
Purpose of the Study:
- To introduce a method for creating 3D-printed axon-mimetic phantoms with complex fibre orientations.
- To characterize the performance of various diffusion MRI models and representations in the presence of orientation dispersion.
Main Methods:
- Developed an open-source 3D printing package to create five axon-mimetic phantoms with varied fibre bending and crossing.
- Acquired diffusion MRI data (9.4T, two-shell) of the phantoms.
- Fitted Diffusion Tensor Imaging (DTI), Diffusion Kurtosis Imaging (DKI), ball and stick model, NODDI, and Bingham-NODDI to the data.
- Compared model outputs to ground-truth maps of fibre orientations.
Main Results:
- DTI's Mean Diffusivity (MD) was insensitive to crossing angle but sensitive to curvature; Axial Diffusivity (AD) decreased with crossing angle.
- DKI metrics mirrored DTI trends; Mean Kurtosis (MK) decreased with curvature, except at high crossing angles.
- Ball and stick model's stick volume fraction decreased with curvature and crossing angle.
- NODDI and Bingham-NODDI showed intra-neurite volume fraction insensitivity to crossing angle; their Orientation Dispersion Index (ODI) correlated with crossing angle.
- Bingham-NODDI's primary ODI correlated with crossing angle, while its secondary ODI did not.
Conclusions:
- Inexpensive 3D-printed phantoms effectively investigate fibre curvature and crossing effects on diffusion MRI models.
- The study revealed the dependence of diffusion MRI representations on fibre dispersion and crossing.
- Bingham-NODDI demonstrated superior performance in characterizing planar fibre dispersion within the phantoms.
