Double-sampled EPI in fMRI: A ghost-free acquisition method with inherent field map correction capability
Lin Y, Chung H, Tsai S, Huang T, Chen N, Kwong K, Chen C, Wu M
National Taiwan University, Brigham and Women's Hospital - Harvard Medical School
Double-sampled EPI (DSEPI) is proposed as a means to improve fMRI quality. Compared with conventional EPI, DSEPI removes Nyquist ghost by separating the k-space data traversed in opposite frequency-encoding directions. The increased geometric distortion due to longer acquisition time is corrected using a field map, which can be generated using the difference in TE for the two sets of data. Experiments on visual fMRI showed SNR improvements by a factor slightly larger than the expected increase from signal averaging alone. It is concluded that DSEPI with inherent field map correction capability is an effective approach for fMRI studies.