Reducing signal loss of the parahippocampal gyrus improves imaging of the default-mode network in 3.0-T MRI: the effect of susceptibility-induced field gradients.
Previous investigations have indicated that the default-mode network (DMN) is highly involved in memory processing in the parahippocampal gyrus (PHC). However, because of susceptibility-related signal loss, parahippocampal activation in the DMN is difficult to detect in resting-state functional MRI experiments that are conducted using a 3.0-T MRI scanner. This study investigated the magnetic field gradients of various brain regions and attempted to compensate for signal loss in the PHC using an optimized slice orientation. The field gradients, signal intensities and DMN functional connectivity (FC) of the PHC were investigated using datasets acquired from 18 healthy volunteers. The results show that the field gradient component parallel to the main magnetic field dominates the PHC. The results indicate that the signal intensities and FC of the DMN are significantly low in the PHC when the slice orientation of the imaging plane is transversal. Whether the voxel dimension is isotropic or anisotropic exerts a minimal effect in altering the slice orientation dependence. In conclusion, the results of this study support the selection of the coronal or sagittal planes for imaging of the DMN.
Department of Electrical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan.
Yu-Sheng
YS
Tseng
Department of Electrical Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan.
Teng-Yi
TY
Huang
Graduate Institute of Applied Physics, National Chengchi University, Taipei, Taiwan.|Research Center for Mind, Brain and Learning, National Chengchi University, Taipei, Taiwan.
Shang-Yueh
SY
Tsai
D000328:Adult; D000465:Algorithms; D001931:Brain Mapping / Q000379:methods*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D009415:Nerve Net / Q000502:physiology*; D020534:Parahippocampal Gyrus / Q000502:physiology*; D015203:Reproducibility of Results; D012146:Rest / Q000502:physiology; D012680:Sensitivity and Specificity; D059629:Signal-To-Noise Ratio
default-mode network (DMN); parahippocampal gyrus (PHC)