Functional MRI of the human amygdala?
In view of an increasing number of publications that deal with functional mapping of the human amygdala using blood oxygenation-level-dependent (BOLD) magnetic resonance imaging, we reevaluated the underlying image quality of T2*-weighted echoplanar imaging (EPI) and fast low angle shot (FLASH) sequences at 2.0-T with regard to susceptibility-induced signal losses and geometric distortions. Apart from the timing of the gradient echoes, the degree of susceptibility influences is controlled by the image voxel size. Whereas published amygdala studies report voxel sizes ranging from 22 to 125 microl, the present results suggest that reliable imaging of the amygdala with BOLD sensitivity requires voxel sizes of 4 to 8 microl or less. Preferentially, acquisitions should be performed with a coronal section orientation. Although high-resolution BOLD MRI is at the expense of temporal resolution and volume coverage, it seems to provide the only solution to this physical problem.
Merboldt
K D
KD
Biomedizinische NMR Forschungs GmbH am Max-Planck-Institut für biophysikalische Chemie, Göttingen, 37070, Germany.
Fransson
P
P
Bruhn
H
H
Frahm
J
J
D000679:Amygdala / Q000033:anatomy & histology / Q000502:physiology*; D001143:Arousal / Q000502:physiology; D016477:Artifacts; D001931:Brain Mapping; D017352:Echo-Planar Imaging; D006801:Humans; D007089:Image Enhancement; D008279:Magnetic Resonance Imaging; D010101:Oxygen Consumption / Q000502:physiology; D015203:Reproducibility of Results