期刊
NEUROIMAGE
卷 14, 期 3, 页码 709-722出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1006/nimg.2001.0869
关键词
fMRI; motion correction; artifact; spurious activation; robust registration
This paper describes several experiments that prove that standard motion correction methods may induce spurious activations in some motion-free fMRI studies. This artifact stems from the fact that activated areas behave like biasing outliers for the difference of square-based measures usually driving such registration methods. This effect is demonstrated first using a motion-free simulated time series including artificial activation-like signal changes. Several additional simulations explore the influence of activation amplitude and extent. The effect is finally highlighted on an actual time series obtained from a 3-T magnet. All the experiments are performed using four different realignment methods, which allows us to show that the problem may be overcome by methods based on a robust similarity measure like mutual information. (C) 2001 Academic Press.
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