A low-cost system for coil tracking during transcranial magnetic stimulation

Area of Science:

• Neuroscience
• Biomedical Engineering
• Medical Imaging

Background:

• Accurate coil placement is crucial for transcranial magnetic stimulation (TMS) efficacy.
• Existing frameless stereotaxic systems (FSS) for TMS coil guidance are costly and impractical for many research settings.
• Need for an affordable and reliable coil positioning solution for TMS.

Purpose of the Study:

• To develop and validate a low-cost TMS coil tracking system.
• To utilize readily available webcams and image processing for coil localization.
• To provide a cost-effective alternative to expensive FSS for TMS applications.

Main Methods:

• Developed a stereovision system with two webcams and retroreflective markers.
• Tracked TMS coil position and orientation relative to a target area.
• Validated accuracy and repeatability in global and local frames.
• Assessed system feasibility by recording motor evoked potentials (MEPs) in human subjects.

Main Results:

• The webcam-based system achieved high accuracy (<5µm position error, <1.1° orientation error).
• Demonstrated excellent repeatability for TMS coil placement.
• Observed enhanced and more consistent motor evoked potentials (MEPs) with system feedback.

Conclusions:

• Webcam-based coil tracking is a feasible and low-cost solution for TMS.
• The developed system offers a practical alternative to expensive FSS.
• This approach can improve the reliability and reproducibility of TMS procedures.