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Fuzzy clustering of gradient‐echo functional MRI in the human visual cortex. Part I: Reproducibility
Author(s) -
Baumgartner Richard,
Scarth Gordon,
Teichtmeister Claudia,
Somorjai Ray,
Moser Ewald
Publication year - 1997
Publication title -
journal of magnetic resonance imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.563
H-Index - 160
eISSN - 1522-2586
pISSN - 1053-1807
DOI - 10.1002/jmri.1880070623
Subject(s) - reproducibility , gradient echo , fuzzy clustering , echo (communications protocol) , computer science , fuzzy logic , pattern recognition (psychology) , cluster analysis , artificial intelligence , visual cortex , nuclear magnetic resonance , medicine , biomedical engineering , magnetic resonance imaging , radiology , neuroscience , chemistry , biology , physics , chromatography , computer network
Reproducibility of human functional MRI (fMRI) studies is essential for clinical and neuroresearch applications of this new human brain mapping method. Based on a recently presented study on reproducibility of gradient‐echo fMRI in the human visual cortex (Moser et al. Magn Reson Imaging 1996; 14:567–579), comparing the performance of three different threshold strategies for correlation analysis, we demonstrate that ( a ) fuzzy clustering is a robust, model‐independent method to extract functional information in time and space; ( b ) intertrial reproducibility of cortical activation is significantly improved by the capability of fuzzy clustering to separate signal contributions from larger vessels, running perpendicular to the slice orientation, from activation apparently close to the primary visual cortex; and ( c ) for repeated single subject studies, SDs of <20% for signal enhancement in approximately 80% of the studies and SDs of <30% for activated area size in approximately 65% of the studies are obtained. This, however, depends also on signal‐to‐noise ratio, (motion) artifacts, and subject cooperation.