Lateralization of amygdala activation in fMRI may depend on phase-encoding polarity.
OBJECTIVE
Susceptibility artifacts along the phase-encoding (PE) direction impact the activation pattern in the amygdala and may lead to systematic asymmetries. We implemented a triple-echo echo-planar imaging (EPI) sequence, acquiring opposite PE polarities along left-right PE direction in a single shot, to investigate its effects on amygdala lateralization.


METHODS
Twelve subjects viewed emotional faces to evoke amygdala activation.


CONCLUSIONS
A region of interest analysis revealed that the lateralization of amygdala responses depended on the PE polarity thus representing a pure method artifact. Alternating PE with multi-echo EPI reduced the artifact. Lateralized fMRI activation in areas with magnetic field inhomogeneities need to be interpreted with caution.
Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, RWTH Aachen University, Aachen, Germany. kamathiak@ukaachen.de
Krystyna A
KA
Mathiak
Mikhail
M
Zvyagintsev
Hermann
H
Ackermann
Klaus
K
Mathiak
D000328:Adult; D000465:Algorithms; D000679:Amygdala / Q000502:physiology*; D016477:Artifacts; D001931:Brain Mapping / Q000379:methods*; D005071:Evoked Potentials / Q000502:physiology; D005239:Fear / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult