Limits to anatomical accuracy of diffusion tractography using modern approaches

Area of Science:

• Neuroimaging
• Neuroscience
• Biomedical Engineering

Background:

• Diffusion MRI fiber tractography is a key tool for mapping brain structural connectivity.
• Existing tractography methods have known limitations in anatomical accuracy.
• Recent advancements aim to improve tractography through better acquisition, modeling, and computation.

Purpose of the Study:

• To rigorously assess the anatomical accuracy of modern diffusion MRI fiber tractography methods.
• To determine if recent technological advances have significantly improved tractography's accuracy.
• To provide a comprehensive evaluation of tractography's inherent limitations.

Main Methods:

• The 3-D Validation of Tractography with Experimental MRI (3D-VoTEM) challenge was organized at ISBI 2018.
• Three independent validation datasets were used: a physical phantom and two ex vivo brain specimens.
• 176 submissions from 9 research groups were analyzed, comparing diverse tractography algorithms and strategies.

Main Results:

• Despite numerous advanced methods, the anatomical accuracy of diffusion MRI fiber tractography has not shown dramatic improvement.
• Results were consistent across various fiber complexities and algorithmic approaches.
• The study confirmed persistent limitations in reconstructing white matter pathways using diffusion MRI data alone.

Conclusions:

• Current diffusion MRI tractography methods have inherent limitations for accurate white matter pathway reconstruction.
• Findings corroborate decades of previous validation studies on tractography accuracy.
• Alternative or combined strategies are needed to achieve precise mapping of brain fiber pathways.