Biophysical Diffusion MRI Models Better Identify White Matter Tracts in Edema

Area of Science:

• Neuroimaging
• Biophysical modeling
• Diffusion MRI

Background:

• White matter (WM) tract detection is crucial for presurgical planning.
• Standard MRI techniques (T1/T2, DTI) struggle to identify WM tracts in edematous regions due to increased extracellular water and isotropic diffusion.
• Advanced biophysical models (NODDI, SM) compartmentalize diffusion signals to overcome these limitations.

Purpose of the Study:

• To evaluate if biophysical multi-compartment models can robustly identify WM tracts within edematous regions.
• To assess the recovery of tractography streamlines in edematous areas using these advanced models.

Main Methods:

• Utilized multi-shell diffusion-weighted MRI data from meningioma patients.
• Compared fractional anisotropy (FA) from standard and free-water-corrected DTI, orientation dispersion index (ODI) from NODDI, and P2 from SM fODF.
• Evaluated tractography performance across models in edematous and contralateral WM regions.

Main Results:

• Biophysical model metrics (1 - ODI and P2) in edema closely matched contralateral measurements.
• Standard DTI metrics (FA, FW-FA) showed substantial reductions in edematous regions.
• (1 - ODI) slightly increased in edema (~8%), while P2 remained unchanged.

Conclusions:

• Biophysical diffusion models demonstrate potential for robust WM tract identification in edematous brain regions.
• These models offer improved preoperative mapping capabilities compared to standard DTI.
• Advanced diffusion modeling aids in overcoming imaging challenges posed by edema during surgical planning.