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GCG+03

G. Garreffa, M. Carni, G. Gualniera, G. B. Ricci, L. Bozzao, D. De Carli, P. Morasso, P. Pantano, C. Colonnese, V. Roma, B. Maraviglia. Real-time MR artifacts filtering during continuous EEG/fMRI acquisition. Magn Reson Imaging, 21(10):1175-1189, 2003.

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Abstract

The purpose of this study was the development of a real-time filtering procedure of MRI artifacts in order to monitor the EEG activity during continuous EEG/fMRI acquisition. The development of a combined EEG and fMRI technique has increased in the past few years. Preliminary "spike-triggered" applications have been possible because in this method, EEG knowledge was only necessary to identify a trigger signal to start a delayed fMRI acquisition. In this way, the two methods were used together but in an interleaved manner. In real simultaneous applications, like event-related fMRI study, artifacts induced by MRI events on EEG traces represent a substantial obstacle for a right analysis. Up until now, the methods proposed to solve this problem are mainly based on procedures to remove post-processing artifacts without the possibility to control electrophysiological behavior of the patient during fMRI scan. Moreover, these methods are not characterized by a strong "prior knowledge" of the artifact, which is an imperative condition to avoid any loss of information on the physiological signals recovered after filtering. In this work, we present a new method to perform simultaneous EEG/fMRI study with real-time artifacts filtering characterized by a procedure based on a preliminary analytical study of EPI sequence parameters-related EEG-artifact shapes. Standard EEG equipment was modified in order to work properly during ultra-fast MRI acquisitions. Changes included: high-performance acquisition device; electrodes/cap/wires/cables materials and geometric design; shielding box for EEG signal receiver; optical fiber link; and software. The effects of the RF pulse and time-varying magnetic fields were minimized by using a correct head cap wires-locked environment montage and then removed during EEG/fMRI acquisition with a subtraction algorithm that takes in account the most significant EPI sequence parameters. The on-line method also allows a further post-processing utilization

Keywords

[ Algorithms ] [ *artifacts ] [ Echo-planar imaging/methods ] [ *electroencephalography/methods ] [ Human ] [ *magnetic resonance imaging/methods ] [ *signal processing ] [ Computer-assisted ] [ Support ] [ Non-u.s. gov't ]

Contact

G. Garreffa
M. Carni
G. Gualniera
G. B. Ricci
L. Bozzao
D. De Carli
P. Morasso
P. Pantano
C. Colonnese
V. Roma
B. Maraviglia

BibTex Reference

@article{GCG+03,
   Author = {Garreffa, G. and Carni, M. and Gualniera, G. and Ricci, G. B. and Bozzao, L. and De Carli, D. and Morasso, P. and Pantano, P. and Colonnese, C. and Roma, V. and Maraviglia, B.},
   Title = {Real-time {MR} artifacts filtering during continuous {EEG}/f{MRI} acquisition},
   Journal = {Magn Reson Imaging},
   Volume = {21},
   Number = {10},
   Pages = {1175--1189},
   Year = {2003}
}

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