Anders Nordell1,2, Stefan Skare2,3
1Medical Physics, Karolinska University Hospital, Stockholm, Sweden; 2Clinical Neuroscience, Karolinska Institute, Stockholm, Sweden; 3Radiology, Stanford University, Palo Alto, CA, USA
An Echo Planar Imaging (EPI) pulse sequence with circular k-space coverage is proposed. Earlier published circular EPI (cEPI) had aimed at shortening the total readout length by varying the echo spacing. In our method, covering the same k-space trajectory, the echo spacing is kept constant. Instead the amplitude is changed in order to increase the SNR along the circular echo planar trajectory while keeping a constant k-space velocity along the phase encoding axis, which is important with respect to spatial distortions. We call this method constant velocity circular EPI (cv-cEPI).