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Real-Time Tractography-Assisted Neuronavigation for Transcranial Magnetic Stimulation
Dogu Baran Aydogan1,2,3, Victor H Souza2,3,4, Renan H Matsuda2,5
1A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland.
Human Brain Mapping
|December 31, 2024
Summary
This study introduces a real-time tractography system to guide navigated transcranial magnetic stimulation (nTMS) by visualizing brain connections. The system enables precise targeting of brain networks, improving treatment for conditions like major depressive disorder.
Area of Science:
- Neuroscience
- Medical Imaging
- Biophysics
Background:
- Navigated transcranial magnetic stimulation (nTMS) uses MRI for coil positioning but lacks real-time visualization of brain connectivity.
- Current neuronavigation systems cannot highlight white-matter pathways during TMS, potentially missing individual brain differences and network targeting opportunities.
- Offline tractography methods are computationally intensive, limiting their use for real-time applications.
Purpose of the Study:
- To develop and assess the feasibility of a real-time tractography-assisted TMS neuronavigation system.
- To enable targeting of specific brain networks and structural connections for improved TMS therapies.
- To account for inter-individual variability in brain connectivity during TMS.
Main Methods:
- Developed a modular framework integrating offline diffusion MRI analysis with online probabilistic tractography using the parallel transport approach.
- Combined open-source software Trekker (tractography) and InVesalius (neuronavigation).
- Evaluated the system using synthetic data and MRI scans from four healthy volunteers, comparing online results with offline tractography.
Main Results:
- The system successfully visualized thousands of streamlines in real-time, showcasing interactive parameter tuning and uncertainty visualization.
- Demonstrated considerable inter-subject variability in streamline counts for TMS targets.
- Real-time tractography rapidly covered substantial portions of target brain area connectivity, often exceeding offline methods' coverage within seconds.
Conclusions:
- Real-time tractography-assisted TMS neuronavigation is feasible and offers a viable approach for targeting brain networks.
- The developed system allows for precise targeting of brain regions and fiber tracts based on individual structural connectivity.
- This approach provides novel visualization techniques for TMS targeting without compromising connectivity estimates compared to offline methods.
