Koninklijke Philips Corporation N.V.

Ulrike Andrea Blume

Johan Michiel Den Harder

Elwin De Weerdt

Michel Paul Jurriaan Jurrissen

Clemens Bos

Gerrit Hendrik Van Ijperen

The invention relates to a method of MR imaging near metal parts using SEMAC. It is an object of the invention to provide an improved MR imaging technique that is sufficiently fast and robust against susceptibility effects. The invention proposes to apply a weaker slice-selection magnetic field gradient (G) for reduction of ripple-artefacts near metal parts or to apply undersampling in the slice-selection direction of the SEMAC sequence or to apply both these aspects. According to one aspect of the invention, a sparsity constraint is used to make the reconstruction of the undersampled MR images more stable. Moreover, the invention relates to a MR device () and to a computer program to be run on a MR device ().

Metal resistant MR imaging

When magnetic resonance imaging in the vicinity of a metallic object (like, for instance, a metal implant), severe spatial perturbations of the static magnetic field occur. In order to suppress the back-folding of distant off-resonant signals into the region of interest, the imaging volume is spatially restricted by selection gradients applied concurrently with the excitation and the refocusing RF pulses in a spin echo sequence. The selection gradient applied during the excitation pulse has an amplitude and/or a polarity different from that of the selection gradient applied during the refocusing pulse so that the respectively selected slices in an off-resonance frequency versus spatial coordinate diagram become tilted with respect to one another. The applied imaging technique may of the SEMAC or MAVRIC type and may incorporate compressed sensing, parallel imaging, fat suppression and/or SVD-based noise reduction.

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Eindhoven, Netherlands

Ulrike Andrea Blume