Optimized preoperative motor cortex mapping in brain tumors using advanced processing of transcranial magnetic...

Area of Science:

• Neurosurgery
• Neuroscience
• Medical Imaging

Background:

• Transcranial magnetic stimulation (TMS) is crucial for localizing motor function before neurosurgery.
• Accurate modeling of TMS effects is essential for reliable motor mapping data.

Purpose of the Study:

• To evaluate different models for analyzing TMS motor mapping data.
• To compare the accuracy of various modeling techniques against direct cortical stimulation (DCS).

Main Methods:

• Twelve patients with perirolandic tumors underwent TMS-based motor mapping.
• Models ranged from simple surface projection to complex electric field analysis using individual head models.
• Probability maps were validated against DCS data, considered the gold standard.

Main Results:

• All models identified the motor cortex location, with point-cloud methods achieving 83-86% accuracy.
• A realistic head model analyzing weighted electric fields provided the best delineation of the motor cortex representation.
• Optimal thresholds for visualization were identified, with dynamic thresholding offering clinical utility.

Conclusions:

• The analysis method significantly impacts the predicted primary motor cortex area.
• Realistic electric field modeling is clinically feasible and superior to simpler methods for motor cortex delineation.