L Engels1, X De Tiege, M Op de Beeck, N Warzée. 1. Laboratory of Image Synthesis and Analysis, Université libre de Bruxelles (ULB), Brussels, Belgium. laurent.engels@ulb.ac.be <laurent.engels@ulb.ac.be>
Abstract
OBJECTIVES: The purpose of this study is to determine the factors influencing the spatial precision and the replicability of electromagnetic trackers (EMT) for the localization of electrodes and natural landmarks on the patient's head. MATERIALS AND METHODS: The effects of seven conditions on the measurement of the EMT were investigated with a Polhemus Fastrack: distance, contact between two components of the EMT, presence of magnetic object, localization of landmarks and electrodes on a phantom and a human subject without and with movements. RESULTS: The EMT has a precision of 0.15mm+/-0.36mm for the measurements made on still objects in a non-magnetic environment. On a human subject, the mean variation of the nasion position is 1.6mm+/-1.46mm and 2.7mm+/-1.40mm for the tragus. The increase of the electrode measurement dispersions is significant between the phantom and the human subject with a mean variation of 2.39mm+/-1.26mm. In certain conditions, up to 15% of the measurements may be considered as outliers. CONCLUSION: The precision significantly decreases for this application in the following cases: (1) physical contacts between the stylus/transmitter/receiver cables, (2) presence of magnetic objects in the surrounding of the EMT system, (3) skin and hair softness and (4) subject's head movements.
OBJECTIVES: The purpose of this study is to determine the factors influencing the spatial precision and the replicability of electromagnetic trackers (EMT) for the localization of electrodes and natural landmarks on the patient's head. MATERIALS AND METHODS: The effects of seven conditions on the measurement of the EMT were investigated with a Polhemus Fastrack: distance, contact between two components of the EMT, presence of magnetic object, localization of landmarks and electrodes on a phantom and a human subject without and with movements. RESULTS: The EMT has a precision of 0.15mm+/-0.36mm for the measurements made on still objects in a non-magnetic environment. On a human subject, the mean variation of the nasion position is 1.6mm+/-1.46mm and 2.7mm+/-1.40mm for the tragus. The increase of the electrode measurement dispersions is significant between the phantom and the human subject with a mean variation of 2.39mm+/-1.26mm. In certain conditions, up to 15% of the measurements may be considered as outliers. CONCLUSION: The precision significantly decreases for this application in the following cases: (1) physical contacts between the stylus/transmitter/receiver cables, (2) presence of magnetic objects in the surrounding of the EMT system, (3) skin and hair softness and (4) subject's head movements.
Authors: Pedro M R Reis; Felix Hebenstreit; Florian Gabsteiger; Vinzenz von Tscharner; Matthias Lochmann Journal: Front Hum Neurosci Date: 2014-03-24 Impact factor: 3.169
Authors: Kitti Kaiboriboon; Hans O Lüders; Mehdi Hamaneh; John Turnbull; Samden D Lhatoo Journal: Nat Rev Neurol Date: 2012-08-07 Impact factor: 42.937
Authors: Christoph Pfeiffer; Lau M Andersen; Daniel Lundqvist; Matti Hämäläinen; Justin F Schneiderman; Robert Oostenveld Journal: PLoS One Date: 2018-05-10 Impact factor: 3.240