Abstract: A method to compensate for the magnetic field heterogeneity inside an object of investigation in a MR device obtains an uncorrected magnetic field distribution of the object and executes an MR sequence with a desired k-space coverage by applying RF pulses to generate a transverse magnetization within the object. MR signal data is recorded, magnetic field shimming parameters are dynamically updated and MR signal data are reconstructed to produce images or localized spectroscopic data. Artifacts in a reconstructed image resulting from an uncorrected magnetic field distribution are suppressed by temporally separating MR signals originating from at least two different sub-volumes within a volume of transverse magnetization by generating a nonlinear phase distribution within the object and by dynamically updating shimming parameters to compensate for the field inhomogeneity distributions within the different sub-volumes in the volume of transverse magnetization.

Abstract: A method of MR imaging applies a magnetic field Bgrad1 having a spatially non-linear dependence to select a volume of at least one curved slice. The slice is described by its midsurface AM, a volume of the selected slice being made up of n? partial volumes in each of which gradients of at least one pair of remaining superimposed magnetic fields Bgradi (i>1) exhibit an angle dependence of 70° to 110° with respect to one another and with respect to the normal of the midsurface AM. At least one superimposed magnetic field of the respective pair exhibits a spatially non-linear dependence and combinations of these pairs are used for spatial encoding. In this way, curved surfaces can be mapped efficiently in high resolution and the method can be adapted to the slice shape.

Abstract: A method for magnetic resonance (=MR) imaging, wherein non-linear gradient fields are applied for the purpose of spatial encoding to acquire images of an object to be imaged and wherein the magnet resonance signal radiated from the object to be imaged is sampled on grids in time, to thereby obtain sampling points, is characterized in that the object to be imaged is mapped completely in regions of stronger gradient fields by increasing the density of the sampling points in the center of k-space, and additional sampling points are specifically acquired in the outer regions of k-space according to a k-space sampling pattern depending on the desired distribution of the resolution in the measurement, wherein the MR measurement is calculated with the additional sampling points. An MR imaging method is thereby provided by means of which homogenized resolution is achieved in the MR measurements using non-linear gradient fields for spatial encoding.

Abstract: A method of MR with spatial encoding to generate an image or spectroscopic data of an object of investigation inside an MR apparatus comprises the steps of (a) selecting a volume of interest within the object of investigation, (b) applying an RF pulse to generate a transverse magnetization within the object of investigation, (c) preparing a nonlinear phase distribution within the object of investigation by application of spatially encoding magnetic fields (SEMs), the SEMs comprising of a nonlinear gradient field or a combination of linear and nonlinear gradient fields, (d) effecting primary spatial encoding through application of SEMs, and (e) recording MR signals originating from the object of investigation. Step (c) or (d) thereby comprises applying a sequence of at least two SEMs, at least one of which contains a nonlinear field gradient and at least two of the SEMs having different field geometries.

Abstract: A method of MR imaging applies a magnetic field Bgrad1 having a spatially non-linear dependence to select a volume of at least one curved slice. The slice is described by its midsurface AM, a volume of the selected slice being made up of n? partial volumes in each of which gradients of at least one pair of remaining superimposed magnetic fields Bgradi (i>1) exhibit an angle dependence of 70° to 110° with respect to one another and with respect to the normal of the midsurface AM. At least one superimposed magnetic field of the respective pair exhibits a spatially non-linear dependence and combinations of these pairs are used for spatial encoding. In this way, curved surfaces can be mapped efficiently in high resolution and the method can be adapted to the slice shape.

Abstract: A method to compensate for the magnetic field heterogeneity inside an object of investigation in a MR device obtains an uncorrected magnetic field distribution of the object and executes an MR sequence with a desired k-space coverage by applying RF pulses to generate a transverse magnetization within the object. MR signal data is recorded, magnetic field shimming parameters are dynamically updated and MR signal data are reconstructed to produce images or localized spectroscopic data. Artifacts in a reconstructed image resulting from an uncorrected magnetic field distribution are suppressed by temporally separating MR signals originating from at least two different sub-volumes within a volume of transverse magnetization by generating a nonlinear phase distribution within the object and by dynamically updating shimming parameters to compensate for the field inhomogeneity distributions within the different sub-volumes in the volume of transverse magnetization.

Abstract: A method of MR with spatial encoding to generate an image or spectroscopic data of an object of investigation inside an MR apparatus comprises the steps of (a) selecting a volume of interest within the object of investigation, (b) applying an RF pulse to generate a transverse magnetization within the object of investigation, (c) preparing a nonlinear phase distribution within the object of investigation by application of spatially encoding magnetic fields (SEMs), the SEMs comprising of a nonlinear gradient field or a combination of linear and nonlinear gradient fields, (d) effecting primary spatial encoding through application of SEMs, and (e) recording MR signals originating from the object of investigation. Step (c) or (d) thereby comprises applying a sequence of at least two SEMs, at least one of which contains a nonlinear field gradient and at least two of the SEMs having different field geometries.

Abstract: A method for magnetic resonance (=MR) imaging, wherein non-linear gradient fields are applied for the purpose of spatial encoding to acquire images of an object to be imaged and wherein the magnet resonance signal radiated from the object to be imaged is sampled on grids in time, to thereby obtain sampling points, is characterized in that the object to be imaged is mapped completely in regions of stronger gradient fields by increasing the density of the sampling points in the center of k-space, and additional sampling points are specifically acquired in the outer regions of k-space according to a k-space sampling pattern depending on the desired distribution of the resolution in the measurement, wherein the MR measurement is calculated with the additional sampling points. An MR imaging method is thereby provided by means of which homogenized resolution is achieved in the MR measurements using non-linear gradient fields for spatial encoding.