title: Internal ventilation system of MR scanners induces specific EEG artifact during simultaneous EEG-fMRI.
abstract: During simultaneous EEG-fMRI acquisition, the EEG signal suffers from tremendous artifacts caused by the scanner "environment". Particularly, gradient artifacts and the ballistocardiogram have been well characterized, along with methods to eliminate them. Here, we describe another systematic artifact in the EEG signal, which is induced by the internal ventilation system of Siemens TRIO and VERIO MR scanners. A ventilation-level dependent vibration induces specific peaks in the frequency spectrum of the EEG. These frequency peaks are in the range of physiologically relevant brain rhythms (gamma frequency range), and thus interfere with their reliable acquisition. This ventilation dependent artifact was most prominent on the electrodes placed directly on the subject's head, so it is not sufficient to simply place the EEG's amplifier outside the scanner tube. Instead, the ventilator must be switched off to fully eliminate the ventilator's artificial manipulation of EEG recordings. Without the internal ventilator system being on, the temperature within the scanner tube may rise, thus requiring shorter scanning sessions or an additional external ventilation system.
authors: Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany. till.nierhaus@charite.de
authors: Till
authors: T
authors: Nierhaus
authors: Christopher
authors: C
authors: Gundlach
authors: Dominique
authors: D
authors: Goltz
authors: Sabrina D
authors: SD
authors: Thiel
authors: Burkhard
authors: B
authors: Pleger
authors: Arno
authors: A
authors: Villringer
mesh_terms: D016477:Artifacts; D004569:Electroencephalography / Q000379:methods*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000379:methods