Diffusion-weighted magnetic resonance imaging

Abstract

In a magnetic resonance apparatus and operating method therefore, 3D navigator data are acquired and are used to correct spatially varying phase errors in contemporaneously acquired imaging data in each shot of a multi-shot data acquisition sequence. A mosaic sampling scheme is used to enter the diffusion-weighted magnetic resonance data and the navigator data into k-space respectively in blocks that each form a subset of the entirety of k-space. The navigator data in each shot are entered into a block that is located at the center of k-space, and, in each shot, the corresponding image data are entered into an offset block in k-space, that is offset in at least one spatial direction from the navigator data block. The offset is varied from shot-to-shot.

Description

technical field [0001] The present invention relates to diffusion weighted magnetic resonance imaging, in particular to a method for correcting phase errors in diffusion weighted magnetic resonance data and a magnetic resonance device. Background technique [0002] Multiple-shot diffusion-weighted imaging (DWI) of the brain is sensitive to spatially correlated nonlinear phase errors caused by CSF (cerebrospinal fluid) pulsations during diffusion-encoding gradients and the impact of cardiac-related pulsatile motion on the brain. figure 1 The phase images in show roughly how these phase errors vary from one shot to the next, as shown in example shots S1, S2, S3, S4, and S5. This leads to severe artifacts in the final image if no correction is applied. [0003] For two-dimensional acquisition, each image plane is excited with separate slice-selected radio frequency (RF) pulses, and techniques have been demonstrated to allow correction of these two-dimensional nonlinear phase e...

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Additionally, data acquired during early systole, when the effects of beating are most pronounced, are discarded and not used during image reconstruction

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