EEG instrumentation and safety

Abstract

The successful combination of electroencephalography (EEG) and fMRI demands careful consideration of three important issues: patient safety, EEG quality and image quality. In this chapter we first consider the implications these factors have on the design of EEG instrumentation, and then examine the precautions that must be taken in order that these recordings can be performed safely. EEG instrumentation comprises electrodes, an acquisition system to amplify and digitise the EEG signals, and review facilities for the display and analysis of the recorded waveforms. The design of EEG instrumentation appropriate for use in the magnetic resonance (MR) scanner must take into account a number of factors that are not applicable to conventional EEG equipment: the presence of static and time-varying magnetic fields and their associated EEG artefacts; the need to limit radiofrequency (RF) emissions to preserve image quality; and finally the obvious requirement to avoid the introduction of ferrous materials into the scanner environment. These considerations dictate that EEG monitoring equipment used for diagnostic recordings in a clinical setting are not suitable for optimal EEG-fMRI monitoring. In this section, we examine the influence the above factors exert on the design of EEG instrumentation. We start at the beginning of the EEG signal chain with a consideration of the electrodes. EEG artefact post-processing correction methods are discussed in detail in the chapters EEG Quality: Origin and Reduction of the EEG Cardiac-Related Artefact and EEG Quality: The Image Acquisition Artefact. © Springer-Verlag Berlin Heidelberg 2010.