Accuracy of high-density EEG electrode position measurement using an optical scanner compared with the photogrammetry method.

ABSTRACT

Objective: To determine the feasibility and accuracy of a handheld optical scanner to measure the three-dimensional (3D) EEG electrode coordinates in a high-density array of 256 electrodes. Methods: We compared the optical scanning with a previously validated method, based on photogrammetry. Electrode coordinates were co-registered with the MRI of the patients, and mean distance error relative to the three-dimensional MRI reconstruction was determined for each patient. We included 60 patients 30 were measured using the photogrammetry method, and 30 age and gender matched patients were measured with the optical scanner. Results: Using the optical scanner, the mean distance error was 1.78 mm (95% confidence interval 1.59-1.98 mm) which was significantly lower (p < 0.001) compared with the photogrammetry method (mean distance error 2.43 mm; 95% confidence interval 2.28-2.57 mm). The real-time scanning took 5-10 min per patient. Conclusions: The handheld optical scanner is more accurate and feasible, compared to the photogrammetry method. Significance: Measuring EEG electrode positions in high-density array, using the optical scanner is suitable for clinical implementation in EEG source imaging for presurgical evaluation.