METAL RESISTANT MR IMAGING

摘要

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 (Gslice) 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 (1) and to a computer program to be run on a MR device (1).

主权项

1. A method of magnetic resonance imaging of at least a portion of a body placed within the examination volume of a magnetic resonance device, the method comprising the steps of:
subjecting the portion of the body to an imaging sequence of radio frequency pulses and a plurality of switched magnetic field gradients, the imaging sequence comprising:
at least one slice-selective or slab-selective excitation radio frequency pulse radiated toward the portion of the body in the presence of a magnetic field gradient in a slice-selection or slab-selection direction for exciting magnetic resonance within a slice or slab,one or more refocusing radio frequency pulses radiated toward the portion of the body temporally subsequent to the excitation radio frequency pulse for generating spin echo signals, anda switched phase-encoding magnetic field gradient in the slice-selection direction for phase-encoding of the spin echo signals, acquiring phase-encoded spin echo signals from a plurality of spatially adjacent slices or slabs, wherein the thickness of the slices or slabs is selected such that spatially adjacent slices or slabs overlap at least partially in the slice-selection or slab-selection direction, and reconstructing a image from the acquired phase-encoded spin echo signals using a sparsity constraint, wherein a slice or slab image is reconstructed for each slice or slab, wherein image values of the magnetic resonance image are computed by combining image values from slice or slab images of different slices or slabs.