Removal of time-varying gradient artifacts from EEG data acquired during continuous fMRI. Export

@article{citeulike:2478872, abstract = {OBJECTIVE: Recording low amplitude electroencephalography (EEG) signals in the face of large gradient artifacts generated by changing functional magnetic resonance imaging (fMRI) magnetic fields continues to be a challenge. We present a new method of removing gradient artifacts with time-varying waveforms, and evaluate it in continuous (non-interleaved) simultaneous EEG-fMRI experiments. METHODS: The current method consists of an analog filter, an EEG-fMRI timing error correction algorithm, and a temporal principal component analysis based gradient noise removal algorithm. We conducted a phantom experiment and a visual oddball experiment to evaluate the method. RESULTS: The results from the phantom experiment showed that the current method reduced the number of averaged samples required to obtain high correlation between injected and recovered signals, compared to a conventional average waveform subtraction method with adaptive noise cancelling. For the oddball experiment, the results obtained from the two methods were very similar, except that the current method resulted in a higher P300 amplitude when the number of averaged trials was small. CONCLUSIONS: The current method enabled us to obtain high quality EEGs in continuous simultaneous EEG-fMRI experiments. SIGNIFICANCE: Continuous simultaneous EEG-fMRI acquisition enables efficient use of data acquisition time and better monitoring of rare EEG events.}, address = {Department of Diagnostic Radiology, Yale University School of Medicine, P.O. Box 208043, TAC Building MRRC Rm. N128, New Haven, CT 06520-8043, USA. michiro.negishi@yale.edu}, author = {Negishi, M. and Abildgaard, M. and Nixon, T. and Constable, R. T.}, citeulike-article-id = {2478872}, citeulike-linkout-0 = {http://dx.doi.org/10.1016/j.clinph.2004.04.005}, citeulike-linkout-1 = {http://view.ncbi.nlm.nih.gov/pubmed/15294222}, citeulike-linkout-2 = {http://www.hubmed.org/display.cgi?uids=15294222}, doi = {10.1016/j.clinph.2004.04.005}, issn = {1388-2457}, journal = {Clin Neurophysiol}, keywords = {artifact, eeg, fmrt}, month = {September}, number = {9}, pages = {2181--2192}, posted-at = {2008-08-07 10:14:19}, priority = {4}, title = {Removal of time-varying gradient artifacts from EEG data acquired during continuous fMRI.}, url = {http://dx.doi.org/10.1016/j.clinph.2004.04.005}, volume = {115}, year = {2004} }

TY - JOUR ID - citeulike:2478872 L3 - citeulike-article-id:2478872 N2 - OBJECTIVE: Recording low amplitude electroencephalography (EEG) signals in the face of large gradient artifacts generated by changing functional magnetic resonance imaging (fMRI) magnetic fields continues to be a challenge. We present a new method of removing gradient artifacts with time-varying waveforms, and evaluate it in continuous (non-interleaved) simultaneous EEG-fMRI experiments. METHODS: The current method consists of an analog filter, an EEG-fMRI timing error correction algorithm, and a temporal principal component analysis based gradient noise removal algorithm. We conducted a phantom experiment and a visual oddball experiment to evaluate the method. RESULTS: The results from the phantom experiment showed that the current method reduced the number of averaged samples required to obtain high correlation between injected and recovered signals, compared to a conventional average waveform subtraction method with adaptive noise cancelling. For the oddball experiment, the results obtained from the two methods were very similar, except that the current method resulted in a higher P300 amplitude when the number of averaged trials was small. CONCLUSIONS: The current method enabled us to obtain high quality EEGs in continuous simultaneous EEG-fMRI experiments. SIGNIFICANCE: Continuous simultaneous EEG-fMRI acquisition enables efficient use of data acquisition time and better monitoring of rare EEG events. IS - 9 JF - Clin Neurophysiol SN - 1388-2457 AD - Department of Diagnostic Radiology, Yale University School of Medicine, P.O. Box 208043, TAC Building MRRC Rm. N128, New Haven, CT 06520-8043, USA. michiro.negishi@yale.edu EP - 2192 TI - Removal of time-varying gradient artifacts from EEG data acquired during continuous fMRI. VL - 115 SP - 2181 KW - artifact KW - eeg KW - fmrt AU - Negishi, M AU - Abildgaard, M AU - Nixon, T AU - Constable, RT PY - 2004/09// UR - http://dx.doi.org/10.1016/j.clinph.2004.04.005 ER -