G01R33/4835

SIMULTANEOUS MULTI-SLICE MAGNETIC RESONANCE IMAGING WITH SPIN EXCITATION USING A MULTI-BAND RADIO-FREQUENCY PULSE

In a method and apparatus for acquiring magnetic resonance (MR) raw data with a simultaneous multi-slice (SMS) data acquisition sequence, nuclear spins respectively in multiple slices of the examination subject are simultaneously excited by radiating, from a radio-frequency (RF) radiator of the MR data acquisition scanner, a multi-band (MB) RF pulse. This MB RF pulse in the SMS data acquisition sequence is generated by radiating and superimposing a number of single band (SB) RF pulses emitted from said RF radiator, each having a respectively different flip angle. Raw MR data are acquired from the multiple slices of the examination subject after the simultaneous excitation of nuclear spins in the multiple slices with said MB RF pulse.

Method and apparatus for acquisition of magnetic resonance data with fat saturation pulses radiated with respectively different flip angles

In a method and apparatus for magnetic resonance imaging of an examination subject using an acquisition sequence that includes at least one acquisition cycle, wherein the acquisition cycle includes a readout block set with at least two readout blocks, and a saturation pulse set with at least two saturation pulses, the saturation pulses of the saturation pulse set are respectively associated with respective readout blocks of the readout block set, and the saturation pulses of the saturation pulse set have respectively varying flip angles.

Apparatus and method using time shifts in magnetic resonance imaging (MRI) to implement controlled aliasing in parallel imaging (CAIPI)

A method and apparatus are provided to perform controlled aliasing in parallel imaging (CAIPI) using time shifts between the radio frequency (RF) excitation pulses and the waveform of the slice-select gradient field to shift respective sampling points within the two-dimensions of k-space corresponding to phase encoding. Thus, a CAIPI sampling pattern is generated using time shifts, rather than by modulating the RF excitation pulses or gradient fields.

System and method for rapid, multi-shot segmented magnetic resonance imaging

A system and method for medical imaging using a magnetic resonance imaging system includes performing a segmented echo planar imaging (EPI) pulse sequence. The pulse sequence includes performing multiple radio frequency (RF) excitation pulses designed to excite multiple imaging slices across the subject simultaneously. A gradient encoding scheme applied along the slice-encoding direction is implemented to impart controlled phase shifts to the different imaging slices. Additionally, the multiple RF excitation pulses can be designed to further control an overlap of imaging data acquired from adjacent slices of the multiple imaging slices based on a selected offset. The acquired imaging data is reconstructed using a parallel imaging reconstruction method that separates overlapped slices in the imaging data to provide a series of images with respective images for each of the multiple imaging slices across the subject.

DETERMINING K-SPACE SAMPLING WITH SEMAC RECORDINGS
20220050159 · 2022-02-17 ·

Acquisition of MR data with a compressed sensing technique in a volume section includes ascertaining an extent of magnetic field distortion within the volume section. A first gradient along a first direction is switched. An RF excitation pulse is radiated for selective excitation of a slice in the volume section while the first gradient is switched. The MR data is acquired in a volume of the volume section that is composed of the slice, a partial volume above the slice, and a partial volume below the slice by executing the following multiple times: switching a first phase-encoding gradient along a second direction; switching a second phase-encoding gradient along the first direction; and reading out the MR data in a k-space line while a readout gradient is switched along a readout direction. A set of k-space lines to be read out for the volume is determined in dependence on the extent.

METHOD OF GENERATING MULTI-BAND RF PULSES

The present invention relates to a method for side-band suppression in a Magnetic Resonance imaging, MRI, system (100), the method comprising providing a first multiband RF pulse for simultaneously exciting at least two slices in a subject (118) at a first and a second frequency band (301,303) and to acquire using the MRI system (100) signals (307, 308) from the excited two slices and at least one additional signal (309) at a third frequency band (305), the additional signal (309) resulting from a sideband excitation of a slice different from the two slices; using the first multiband RF pulse for determining the additional signal (309); deriving a pre-compensating term from the first multiband RF pulse and the additional signal (309), adding the pre-compensating term to the first multiband RF pulse to obtain a second multiband RF pulse, thereby replacing the first multiband RF pulse by the second multiband RF pulse for suppressing at least part of the additional signal (309).

System And Method For Accelerated Angiographic Magnetic Resonance Imaging
20170248670 · 2017-08-31 ·

A magnetic resonance method and system are provided for projection MR imaging of vascular structures within a subject, with scan times that are shorter than those needed for conventional techniques. Image acquisition sequences are synchronized with heartbeat cycles of the subject, and are configured to generate image data having a reduced spatial resolution in the projection direction perpendicular to a preselected projection plane. A reduction factor F quantifies this reduced resolution, such that the number of data acquisition sequences provided within each heartbeat cycle is F times as many as a comparable imaging protocol that generates full-resolution data. The total scan time can be reduced by a factor of F with negligible degradation in the projection image quality.

Magnetic resonance imaging apparatus

A magnetic resonance imaging apparatus according to an embodiment includes an acquiring unit, a detecting unit, a deriving unit, and an imaging controller. The acquiring unit acquires three-dimensional image data including a target organ. The detecting unit detects an upper end position and a lower end position of the target organ in the three-dimensional image data. The deriving unit derives an imaging range of subsequent imaging performed after acquisition of the three-dimensional image data based on the upper end position and the lower end position of the target organ. The imaging controller controls performance of the subsequent imaging in accordance with the imaging range.

Chemical exchange saturation transfer magnetic resonance imaging with gating synchronized acquisition
11428768 · 2022-08-30 · ·

Methods and systems for producing a magnetic resonance (MR) image of a subject include acquiring a first physiological monitoring signal related to a first physiological process of the subject and acquiring a second physiological monitoring signal related to a second physiological process of the subject. The method also includes analyzing the first physiological monitoring signal and the second physiological monitoring signal to identify at least a first trigger point and a second trigger point and, upon identifying the first trigger point, applying a radiofrequency (RF) saturation module at a selected frequency to saturate a selected spin species in the subject. Upon identifying the second trigger point, the method includes performing a chemical exchange striation transfer (CEST) readout to acquire CEST data and then reconstructing the CEST data to produce a CEST image of the subject.

MAGNETIC RESONANCE TOMOGRAPHY APPARATUS AND METHOD FOR THE OPERATION THEREOF

In a magnetic resonance tomography scanner and an operating method therefor, a scanning volume is subdivided in a slice direction into multiple scanning slices, and the scan data of each of the scanning slices are acquired by a scan sequence allocated to the respective scanning slice. Each scan sequence has at least one preparation pulse allocated to the scanning slice, which causes nuclear spin excitation throughout the whole scanning volume. At least two scan sequences are implemented that differ with regard to a coil current fed during the preparation pulse to a field correction coil of the scanner for reducing a local inhomogeneity of a basic magnetic field, or that differ with regard to at least one pulse parameter of the preparation pulse. The respective coil current and/or pulse parameter is determined depending on the position of the scanning slice allocated to the respective scan sequence in the scanning volume.