Abstract: A method for magnetic resonance imaging uses an electromagnet [304], which may have open geometry, to generate a spatially nonuniform magnetic field within an imaging region [306]. The current through the electromagnet is controlled to repeatedly cycle the nonuniform magnetic field between a high strength for polarizing spins and a low strength for spatial encoding and readout. Using RF coils [308], excitation pulses are generated at a frequency that selects a non-planar isofield slice for imaging. The RF coils are also used to generate refocusing pulses for imaging and to generate spatial encoding pulses, which may be nonlinear. Magnetic resonance signals originating from the selected non-planar isofield slice of the nonuniform magnetic field in the imaging region [306] are detected using the RF coils [308] in parallel receive mode. MRI images are reconstructed from the parallel received magnetic resonance signals, e.g., using algebraic reconstruction.

Abstract: A method for magnetic resonance imaging uses an electromagnet [304], which may have open geometry, to generate a spatially nonuniform magnetic field within an imaging region [306]. The current through the electromagnet is controlled to repeatedly cycle the nonuniform magnetic field between a high strength for polarizing spins and a low strength for spatial encoding and readout. Using RF coils [308], excitation pulses are generated at a frequency that selects a non-planar isofield slice for imaging. The RF coils are also used to generate refocusing pulses for imaging and to generate spatial encoding pulses, which may be nonlinear. Magnetic resonance signals originating from the selected non-planar isofield slice of the nonuniform magnetic field in the imaging region [306] are detected using the RF coils [308] in parallel receive mode. MRI images are reconstructed from the parallel received magnetic resonance signals, e.g., using algebraic reconstruction.

Abstract: In a method of magnetic resonance imaging, a set of nonlinear, mutually orthogonal magnetic gradient encoding fields are sequentially and separately generated in an imaging region [100]. Using multiple receiver coils having nonuniform sensitivity profiles, echo data representing signal intensities in the imaging region is sequentially acquired as the magnetic gradient encoding fields are sequentially generated [102]. A reconstructed image of the imaging region is computed from the acquired echo data [104], and the reconstructed image is then be stored and/or displayed on a display monitor [106].

Abstract: In a method of magnetic resonance imaging, a set of nonlinear, mutually orthogonal magnetic gradient encoding fields are sequentially and separately generated in an imaging region [100]. Using multiple receiver coils having nonuniform sensitivity profiles, echo data representing signal intensities in the imaging region is sequentially acquired as the magnetic gradient encoding fields are sequentially generated [102]. A reconstructed image of the imaging region is computed from the acquired echo data [104], and the reconstructed image is then be stored and/or displayed on a display monitor [106].

Abstract: Truncation artifacts in NMR images are reduced by splicing to the truncated data extrapolated high frequency data derived from the truncated image. The truncated data is Fourier transformed into image space and processed with an edge enhancing filter. The retransformed, filtered data yields edge derived high frequency information that may augment the truncated data. The spliced truncated data and edge enhanced data are then reconstructed into an artifact reduced image. In one embodiment, the edge enhancement is performed by iterative passes of a modified Sigma filter. The spliced data is blended with the truncated data near the regions of the splice by means of a weighted average.