A Preliminary Study on Precision Image Guidance for Electrode Placement in an EEG Study

Abstract

Conventional methods for positioning electroencephalography electrodes according to the international 10/20 system are based on the manual identification of the principal 10/20 landmarks via visual inspection and palpation, inducing intersession variations in their determined locations due to structural ambiguity or poor visibility. To address the variation issue, we propose an image guidance system for precision electrode placement. Following the electrode placement according to the 10/20 system, affixed electrodes are laser-scanned together with the facial surface. For subsequent procedures, the laser scan is conducted likewise after positioning the electrodes in an arbitrary manner, and following the measurement of fiducial electrode locations, frame matching is performed to determine a transformation from the coordinate frame of the position tracker to that of the laser-scanned image. Finally, by registering the intra-procedural scan of the facial surface to the reference scan, the current tracking data of the electrodes can be visualized relative to the reference goal positions without manually measuring the four principal landmarks for each trial. The experimental results confirmed that use of the electrode navigation system significantly improved the electrode placement precision compared to the conventional 10/20 system (p < 0.005). The proposed system showed the possibility of precise image-guided electrode placement as an alternative to the conventional manual 10/20 system.

Comparison between a wireless dry electrode EEG system with a conventional wired wet electrode EEG system for clinical applications

“…The EEG technician selected the best cap fitting the individual subject's head from three possible sizes. Following recommendations 31 , an average precision of about 4 mm can be expected with this procedure compared to coordinates determined by a laser optic procedure in that study.…”

EEG-Based Emotion Recognition: A State-of-the-Art Review of Current Trends and Opportunities

“…The difference here is that the type of electrodes used to collect the brainwave signals affects the quality as well as the duration of setup [ 5 – 7 ]. There are also a different number of electrodes placed across the human scalp, and the resolution of these EEG headsets differs depending on the build quality and technological accessibility [ 8 – 10 ]. Due to the sensitivity of the electrodes, many users are required to be very static when the brainwave collection procedure is initiated, and any small body or head movements may accidentally detach the electrodes out from the scalp and require to be reattached to the head which could waste time and materials.…”

Augmented reality-based electrode guidance system for reliable electroencephalography

“…Considering the system configuration, the conventional 10–20 positioning systems is simple and inexpensive, but an unreliable electrode positioning can occur from the manual identification of the anatomical landmarks [ 7 , 8 , 13 – 15 ]. To address this issue, an extra device such as a vision-based position tracker, a commercial ultrasonic digitizer or a magnetic digitizer has been used so far [ 4 , 6 , 9 ]. Compared to those system, only an RGB-D camera is necessary in the proposed system.…”

“…To address this issue, Jeon and Chien [ 9 ] proposed a preliminary study for precise image-guided electrode placement. A vision-based position tracker and a laser scanner were used for electrode guidance.…”