Patent classifications
G01R33/243
Methods and apparatus for magnetic field shimming
A method of producing a permanent magnet shim configured to improve a profile of a B.sub.0 magnetic field produced by a B.sub.0 magnet is provided. The method comprises determining deviation of the B.sub.0 magnetic field from a desired B.sub.0 magnetic field, determining a magnetic pattern that, when applied to magnetic material, produces a corrective magnetic field that corrects for at least some of the determined deviation, and applying the magnetic pattern to the magnetic material to produce the permanent magnet shim. According to some aspects, a permanent magnet shim for improving a profile of a B.sub.0 magnetic field produced by a B.sub.0 magnet is provided. The permanent magnet shim comprises magnetic material having a predetermined magnetic pattern applied thereto that produces a corrective magnetic field to improve the profile of the B.sub.0 magnetic field.
Dual resolution Dixon magnetic resonance imaging
The invention provides for a magnetic resonance imaging system (100). Machine executable instructions (140) cause a processor controlling the magnetic resonance imaging system to control (200) the magnetic resonance imaging system with the pulse sequence commands to acquire two point Dixon magnetic resonance data and single point Dixon magnetic resonance data; calculate (202) a first resolution magnetic field inhomogeneity map (148) using the two point Dixon magnetic resonance data; calculate (204) a second resolution magnetic field inhomogeneity map (154) by interpolating the first resolution magnetic inhomogeneity map to the second resolution; and calculate (206) a second resolution water image (156) and a second resolution fat image (158) using the single point Dixon magnetic resonance imaging data and the second resolution magnetic field inhomogeneity map. The first resolution is lower than the second resolution.
Emulation mode for MRI
A magnetic resonance imaging system is configured to be selectively operated in a default mode and an emulation mode. Execution of machine executable instructions by a processor of the magnetic resonance imaging system causes the magnetic resonance imaging system to receive a selection signal selecting the emulation mode. The magnetic resonance imaging system switches from the default mode to the emulation mode. The magnetic resonance imaging system is operated in the emulation mode using the set of emulation control parameters. The emulated magnetic resonance imaging data is acquired from the imaging zone of the magnetic resonance imaging system.
Method and device for taking account of the magnetic resonance signal during interference suppression
A method for suppressing interference signals during an image acquisition with a magnetic resonance tomography scanner that has an antenna and an interference signal sensor is provided. The magnetic resonance tomography scanner receives a reference interference signal via the interference signal sensor, receives a magnetic resonance signal via the antenna, and reduces a portion of an interference signal in the magnetic resonance signal as a function of the reference interference signal. During the reduction of the interference signal, the method takes into account the fact that the reference interference signal also has a signal portion of the magnetic resonance signal.
Magnetic resonance imaging method and system and computer-readable storage medium
Embodiments of the present invention provide a magnetic resonance imaging method and system and a computer-readable storage medium. The method comprises: performing pre-scanning, wherein a first sequence and a second sequence are separately performed on a plurality of slices; in the first sequence, two echoes are continuously obtained to respectively obtain first image data and second image data having a first phase offset; in the second sequence, two echoes are continuously obtained to respectively obtain third image data and fourth image data having a second phase offset, the first phase offset and the second phase offset having opposite directions but the same angle; obtaining a plurality of radio-frequency field maps respectively corresponding to the plurality of slices based on the first image data and the second image data, and obtaining a plurality of static magnetic field maps respectively corresponding to the plurality of slices based on at least one of the following two groups: a first image and a third image, and a second image and a fourth image; and calculating formal scanning parameters suitable for a corresponding slice based on at least one of the following two components: each radio-frequency field map, and a corresponding static magnetic field map.
TIME-SAVING GENERATION OF A B0 MAP BASED ON A DUAL ECHO SEQUENCE WITH STIMULATED ECHOES
The disclosure relates to a method for generating a B.sub.0 map for a magnetic resonance examination of an examination subject, a magnetic resonance device, and a computer program product for executing the method. The method provides for the application of at least two preparatory RF pulses during a preparatory stage and at least one readout RF pulse during an acquisition stage. At least one stimulated echo signal is acquired after the readout RF pulse. A B.sub.0 map that shows the actual spatial distribution of the magnetic field strength of the main magnetic field is derived from the at least one acquired FID echo signal and the at least one acquired stimulated echo signal.
ECHO-SPECIFIC K-SPACE SAMPLING WITH MULTI-ECHO SEQUENCES
In a method, an imaging sequence is irradiated into an examination region in which an examination object is located. The imaging sequence includes an acquisition section. The acquisition section includes acquiring a plurality of echo signals, each of which samples a k-space region of a k-space. The plurality of echo signals comprises a plurality of first echo signals and a plurality of second echo signals. The plurality of first echo signals and the plurality of second echo signals are generated from different magnetization configurations. The k-space regions sampled by the plurality of first echo signals sample the k-space in a different order to the k-space regions sampled by the plurality of second echo signals.
METHODS FOR PRODUCING MAGNETIC RESONANCE IMAGES WITH SUB-MILLISECOND TEMPORAL RESOLUTION
A system and method for producing a series of time-resolved magnetic resonance (MR) images is set forth. The system can perform method steps of encoding spatial information into an MRI signal by manipulating a phase of the MRI signal within an MRI system, generating and outputting a phase-encoded MRI signal over time by digitizing a plurality of time points in the MRI signal, repeating the generating and outputting step for a plurality of phase-encoded signals, each phase-encoded signal in synchrony with a trigger, producing a plurality of digitized time points, and reconstructing a series of time resolved MR images, each image of the series of MR images at one specific time point selected from the plurality of digitized time points for each phase-encoded step. Each image in the series of time-resolved MR images corresponding to a specific time point in a cyclic event.
Distortion correction of multiple MRI images based on a full body reference image
Methods, systems, products, devices, and/or apparatus generally related to distortion correction of multiple MRI images based on a full body reference image. An example method for distortion correction of multiple MRI images based on a full body reference image may include acquiring at least one reference image of a subject using a magnetic resonance imaging system, storing a correction field map based on the at least one reference image, the correction field map including information regarding a correction field for each of a plurality of portions of the subject, acquiring a plurality of images by the magnetic resonance imaging system, each of the plurality of images corresponding to a respective portion of the subject, and while acquiring each of the plurality of images, applying a correction field specified by the correction field map for the respective portion of the subject.
Magnetic resonance imaging device, magnetic resonance imaging method and susceptibility calculation program
Accuracy degradation due to a signal loss is reduced, and susceptibility is calculated with high accuracy where, by using an MRI, at least one echo is acquired where spatial magnetic field inhomogeneity is reflected, and a complex image is calculated from the acquired echo. Three masks are calculated from the calculated complex image; a low-signal region mask representing a low signal region, a first high-signal region mask representing a high signal and high fat content region, and a second high-signal region mask representing a high signal and low fat content region. In calculating a susceptibility image from a frequency image or a magnetic field image generated from the complex image, the susceptibility image is obtained under the constraint that a region defined by the low-signal region is set as a background and the susceptibility of the region defined by the second high-signal region mask is set to a specific value.