Diffusion‐weighted interleaved echo‐planar imaging with a pair of orthogonal navigator echoes

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Abstract
This work describes a diffusion‐weighted (DW) interleaved echo‐planar imaging (IEPI) method for use on either conventional whole‐body scanners or scanners equipped with highspeed gradient and receiver hardware. In combination with cardiac gating and motion correction with a pair of orthogonal navigator echoes, the presented method is time‐efficient, compensates for patient motions, and is less sensitive to image distortions than single‐shot methods. The motion‐correction scheme consists of correction for constant and linear phase terms found from the orthogonal navigator echoes. The correction for the linear phase term in the phase‐encode direction includes gridding the data to the Cartesian grid. The DW IEPI was used to image a phantom rotating about the slice‐select direction, and motion correction was performed to eliminate ghost artifacts arising from motion in either the readout‐ or phase‐encoding directions. DW IEPI with motion correction was performed on a normal volunteer and on a patient with a 26‐day‐old region of ischemia over much of the right hemisphere.