NMR in biomedicine
-
Single-shot echo-planar imaging (EPI) is an important method for MRI of the brain. A method has been developed to double the resolution of EPI in the phase-encode direction, without requiring increases in the maximum gradient amplitude or slew rate. The new approach is based on an EPI implementation of the TRAIL (two reduced acquisitions interleaved) method, in which two images, acquired in rapid succession, are spatially interleaved. ⋯ However, the individual readouts do not increase in length, so there is no increase in image blurring, and distortion is halved as a result of the closer temporal spacing of the acquired k-space lines. A correction method is also presented to remove additional potential Nyquist ghosting. The new method is demonstrated in vivo at 4.7 T and could in principle be combined with existing approaches for increasing resolution, such as partial Fourier or parallel imaging.