Spectral-spatial pulse design for through-plane phase precompensatory slice selection in T2*-weighted functional MRI.
T(2)*-weighted functional MR images suffer from signal loss artifacts caused by the magnetic susceptibility differences between air cavities and brain tissues. We propose a novel spectral-spatial pulse design that is slice-selective and capable of mitigating the signal loss. The two-dimensional spectral-spatial pulses create precompensatory phase variations that counteract through-plane dephasing, relying on the assumption that resonance frequency offset and through-plane field gradient are spatially correlated. The pulses can be precomputed before functional MRI experiments and used repeatedly for different slices in different subjects. Experiments with human subjects showed that the pulses were effective in slice selection and loss mitigation at different brain regions.
Yip
Chun-Yu
CY
Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan, USA. chunyuy@nmr.mgh.harvard.edu
Yoon
Daehyun
D
Olafsson
Valur
V
Lee
Sangwoo
S
Grissom
William A
WA
Fessler
Jeffrey A
JA
Noll
Douglas C
DC
D000465:Algorithms; D001921:Brain / Q000502:physiology*; D001931:Brain Mapping / Q000379:methods*; D005071:Evoked Potentials / Q000502:physiology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted