Rotating diffusion mr imaging reduced motion artifacts

Abstract

Within a selected slice or slab, diffusion sensitizing gradients (54, 56) and read gradients (66, 68) are induced along each of a pair of orthogonal axes (G.sub.x, G.sub.y). The motion sensitizing gradient pulses sensitize excited magnetic resonance to diffusion in a preselected diffusion direction (D) which is orthogonal to a selected read gradient direction. The diffusion sensitizing gradients are rotated by sin(.theta.+.pi./2) and cos(.theta.+.pi./2) and the read gradients are rotated by sin.theta. and cos.theta. to generate a plurality of angularly displaced data lines. The diffusion sensitivity direction remains perpendicular to the read direction in each of the angularly displaced data lines. The phase of each data line is determined (90) and shifted (94) to compensate for linear translations. The data values within each data line are shifted (86) to center the peak amplitude of the data line at a preselected position to compensate for higher order motion. The set of angularly incremented data lines are reconstructed (96) into an image representation (98). In one embodiment, a plurality of the images are generated, each from data lines with their peak value shifted to a location which is offset by a fraction of a sample relative to the data lines which constructed the other images. Corresponding patches of these corresponding images are examined (110) for phase. Based on the examination, the one of the corresponding patches with the best image quality is transferred to a final image memory (114). In this manner, the final image is made up of the best patches of a plurality of corresponding images.