Abstract: A device performs MR imaging of a body (7) placed in a stationary and substantially homogeneous main magnetic field, with an RF transmit antenna (6) for radiating RF pulses towards the body (7), which RF transmit antenna (6) has different resonance modes. In order to improve image uniformity in high field MR imaging, the device (1) is arranged to determine the size and/or the aspect ratio of the body (7), and to acquire an MR image of the body (7) by an imaging sequence including RF pulses. The phases and amplitudes of the different resonance modes of the RF transmit antenna (6) excited during irradiation of the RF pulses are controlled on the basis of the size and/or aspect ratio of the body (7).

Abstract: The invention relates to a device for MR imaging of a body (7) placed in a stationary and substantially homogeneous main magnetic field, with an RF transmit antenna (6) for radiating RF pulses towards the body (7), which RF transmit antenna (6) has different resonance modes. In order to improve image uniformity in high field MR imaging, the invention proposes the device (1) being arranged to determine the size and/or the aspect ratio of the body (7), and to acquire an MR image of the body (7) by means of an imaging sequence comprising RF pulses, wherein the phases and amplitudes of the different resonance modes of the RF transmit antenna (6) excited during irradiation of the RF pulses are controlled on the basis of the size and/or aspect ratio of the body (7).

Abstract: In a magnetic resonance imaging method magnetic resonance signal samples are received for a predetermined field of view by a receiving antenna having a spatial sensitivity profile. The sampling in the k space corresponds to the predetermined field of view in the geometrical space. Folded-over images having folded-over pixel values are reconstructed from the sampled magnetic resonance signals. Pixel contributions for spatial positions within the predetermined field of view are calculated from the folded-over pixel values and the spatial sensitivity profile of the receiver antenna. The magnetic resonance image is formed from the pixel contributions for spatial positions within the predetermined field of view. Thus, aliasing or fold-over artefacts caused by a field of view that is too small are avoided.

Abstract: The invention relates to a method for shimming a main magnetic field in a magnetic resonance device. The method comprises the steps of generating at least one spatially selective radio frequency pulse (RF) for exciting nuclear spin magnetization within a restricted region of the examination volume of the magnetic resonance device, acquiring a magnetic resonance signal (ES) that is sensitive to the homogeneity of the main magnetic field, and applying electric currents (SZ, SX, SY) to a shim coil arrangement of the magnetic resonance device such that the main magnetic field is adjusted in accordance to the properties of the acquired magnetic resonance signal (ES).

Abstract: A novel magnetic resonance imaging method is presented to produce a magnetic resonance image, wherein a stationary magnetic field and temporary magnetic gradient fields are applied. A sensitivity distribution (W(p)) maps the receiver sensitivity values of the receiver antennae system in an image domain. Transposition values (p(x)) map the positions in a spatial domain onto pixels (voxels) in the image domain on the basis of actual values of the stationary magnetic field and the temporary gradient fields. A folded image having aliased pixels (voxels) is then reconstructed from the magnetic resonance signals on the basis of a spatial encoding induced by the temporary magnetic field gradients. The aliased pixels (voxels) in the folded image are unfolded on the basis of the spatial receiver sensitivity map onto the respective signal distributions originating from different positions in the spatial domain so as to reconstruct the magnetic resonance image.