Assessment of a diffusion phantom for quality assurance in brain microstructure diffusion MRI studies

Area of Science:

• Neuroimaging
• Biomedical Engineering
• Medical Physics

Background:

• Diffusion-weighted imaging (DWI) in MRI assesses brain microstructure by tracking water molecule displacement.
• Common DWI models include DTI, DKI, and NODDI, used in research and clinics.
• Lack of standardized methods hinders validation of diffusion model stability and repeatability.

Purpose of the Study:

• To evaluate a DTI phantom as a standard reference for validating diffusion MRI models.
• To assess the repeatability and temporal stability of diffusion models using phantom and in vivo data.
• To investigate the impact of gradient coil heating on measurement consistency.

Main Methods:

• Repeated MRI scans of a DTI phantom and four healthy volunteers on different days.
• Fitting acquired data to diffusion models (DTI, DKI, NODDI).
• Assessing phantom repeatability with coefficient of variation (CoV) and in vivo stability with repeatability coefficient (RC).
• Consecutive phantom scans to evaluate gradient coil heating effects.

Main Results:

• The DTI phantom demonstrated high reproducibility, with CoVs below 5% across acquisitions.
• In vivo scans showed low RCs, indicating stable diffusion model performance over time.
• Phantom data confirmed the robustness of diffusion models, unaffected by gradient coil heating.

Conclusions:

• DTI phantoms serve as essential, reproducible references for validating diffusion MRI models.
• The study establishes a framework for standardizing diffusion MRI measurements.
• Future multi-center studies are proposed to assess inter-scanner variability and integrate phantoms into calibration protocols.