On electromagnetic head digitization in MEG and EEG.

Area of Science:

• Neuroimaging
• Biomedical Engineering
• Medical Physics

Background:

• Head digitization accuracy is critical for co-registration in MEG/EEG source imaging.
• Electromagnetic tracking (EMT) systems, like Fastrak, are commonly used but can be affected by interference, challenging sub-millimeter accuracy.
• Precise digitization improves co-registration and enables individualized template MRIs for conductivity modeling.

Purpose of the Study:

• To evaluate the performance of the Fastrak EMT system for MEG/EEG digitization under various conditions.
• To explore the usability of alternative EMT systems (Aurora and a short-range Fastrak) for head digitization.
• To compare the accuracy and robustness of these systems against the standard Fastrak.

Main Methods:

• Performance evaluation of Fastrak, Aurora, and a modified Fastrak system.
• Testing involved digitization accuracy, tracking fluctuation, and system robustness.
• Evaluations used test frames and human head models under different operating conditions.

Main Results:

• The Fastrak system demonstrates accuracy and robustness for MEG/EEG digitization when used within recommended operating conditions.
• The Fastrak with a short-range transmitter exhibited increased digitization error when not used in close proximity to the transmitter.
• The Aurora system showed potential for MEG/EEG digitization within a limited range, with its real-time error estimation feature noted for improving accuracy.

Conclusions:

• The Fastrak EMT system is a reliable tool for MEG/EEG digitization when optimal conditions are maintained.
• Alternative systems like Aurora require modifications for practical use but offer potential benefits, such as real-time error estimation.
• Ensuring proper operating conditions is key to achieving high-accuracy head digitization for MEG/EEG studies.