91 results about "Magnetic resonance sequence" patented technology

A magnetic resonance method comprises: performing (C1) a magnetic resonance procedure on a calibration subject including an implant device; detecting (C2) a pick-up coil (PUC) signal at least during a radio frequency transmit phase of operation (C1); performing (C3) three dimensional temperature mapping of the calibration subject using a magnetic resonance sequence configured to detect any temperature change induced in any part of the implant device by operation (C1); generating (C4) an unsafe condition criterion (30) for the detected PUC signal based on correlating a PUC signal characteristic detected by operation (C2) with a temperature change detected by operation (C3); performing (M5) the magnetic resonance procedure on a subject containing an implant device; detecting (M6) a PUC signal at least during a radio frequency transmit phase of operation (M5); and monitoring (M7) for an unsafe condition indicated by the PUC signal detected in operation (M6) satisfying the unsafe condition criterion (30).

The invention relates to a method for establishing a body lumbar three-dimensional simulation model through registration and fusion of CT (Computed Tomography) and MRI (Magnetic Resonance Imaging) signals. The method comprises the steps of collecting a computed tomography (CT) image; collecting a magnetic resonance imaging (MRI) image; establishing a computed tomography image three-dimensional model; establishing a magnetic resonance imaging image three-dimensional; and carrying out registration and fusion on the computed tomography image three-dimensional model and the magnetic resonance imaging image three-dimensional, wherein the registration and fusion comprise carrying out simple registration and global computing registration according to a lumbar anatomic structure. According to themethod, existing routine examinations such as computed tomography and magnetic resonance imaging are utilized fully, through combination of optimized magnetic resonance scanning sequences, lumbar intervertibral disc, nerve root and ligamentum flavum important soft tissue three-dimensional models capable of mutually verifying accuracy in various magnetic resonance sequences are established, a new lumbar intervertibral disc medical image high-accuracy modeling mode is established, and a utilization rate of medical image examination data is greatly improved.

A magnetic resonance imaging system includes a magnetic resonance imaging scanner (10) that performs an inversion recovery magnetic resonance excitation sequence (70) having a blood-nulling inversion time (60) determined based on a blood T1 value appropriate for a selected magnetic field and blood hematocrit, whereby magnetic resonance of blood is substantially nulled. The inversion recovery excitation sequence (70) includes an inversion radio frequency pulse (74) applied with a small or zero slice-selective magnetic field gradient pulse to avoid inflow effects, and an excitation radio frequency pulse (80). The inversion pulse (74) and excitation pulse (80) are separated by the inversion time (60). The magnetic resonance imaging scanner (10) subsequently performs a readout magnetic resonance sequence (72) or spectroscopy sequence to acquire a magnetic resonance signal from tissue other than the nulled blood. A reconstruction processor (44) generates a reconstructed image from the acquired magnetic resonance signal.

In a method for acquiring magnetic resonance data with a magnetic resonance system using a magnetic resonance sequence, the sequence has a first partial sequence in which magnetic resonance data are acquired for multiple slices that have to be acquired simultaneously, from which image data for the individual slices are calculated by a reconstruction algorithm. The sequence also has a second partial sequence for determining additional data, which are used to evaluate and/or assess the magnetic resonance data, and which have a spatial resolution that is lower than the magnetic resonance data, in which radio-frequency pulses and readout processes take place in a slice-specific manner through a time offset within a single measuring process, in which a single continuous excitation period with the radio-frequency pulses and a single continuous readout period with the readout processes follow one another, so that separate additional data are directly determined for each slice.

In a method and apparatus for magnetic resonance imaging, a particularly quiet magnetic resonance sequence, uses echo-planar imaging with at least one gradient switching in a readout direction, wherein the at least one gradient switching in the readout direction has a slew rate that is less than a maximum slew rate defined by system specification parameters of the magnetic resonance apparatus.

In a method and magnetic resonance apparatus to acquire magnetic resonance data with a diffusion-weighted magnetic resonance sequence wherein the magnetic resonance apparatus as a gradient coil arrangement with three gradient coils designed to generate a gradient in gradient directions orthogonal to one another, the readout gradient is flipped relative to at least one of the gradient directions such that at least two gradient coils contribute to a possible slew rate of a readout gradient pulse, and such that a phase coding gradient that is constant over the readout time period is selected.

Methods for quickly estimating apparent diffusion coefficient probability density functions (ADC PDFs) for each image voxel are provided using a “diffusion reproducibility evaluation and measurement” (DREAM) magnetic resonance sequence. Non-diffusion-weighted (reference) images collected simultaneously have blood oxygenation level dependent (BOLD) sensitivity that can be used for resting-state fMRI data to measure functional connectivity, an unbiased parameter reflecting neurological integrity. ADC coefficient of variation (ADC CV) measurements can be used to isolate and label regions of non-enhancing tumor and predict future enhancement independent of FLAIR, T2, or average ADC maps. Functional diffusion mapping (fDMs) using voxel-wise changes in ADC PDFs can be used to spatially visualize and statistically quantify response to treatment. Additionally, the temporal (time-resolved) diffusivity information can be used for real-time MR thermometry, which is useful for cancer treatment monitoring, and for microperfusion quantification, and tumor/tissue characterization.

A magnetic resonance sequence includes a repetitively applied radiofrequency B₁ pulse capable of causing a specific absorption rate (SAR) hot spot. The composition of the repetitive B₁ pulse is varied to generate versions of the repetitive B₁ pulse such that the SAR hot spot changes locations with subsequent applications of the repetitive B₁ pulse. To generate versions of the B₁ pulse, a pilot scan is performed to generate a patient model. A simulation of the SAR response to each of the versions of the repetitive B₁ pulse is performed to determine the location of SAR hot spot(s). A plurality of versions of the repetitive B₁ pulse is selected to be used in the magnetic resonance sequence.

A local radio frequency (RF) transmitting coil (26) of a magnetic resonance imaging system (5) has a plurality of coil elements (100). Each coil element (100) has an adjustable load (62) which is adjusted by a control unit (60) to adjust a transmitted B1field distribution. The load can be adjusted to shim for a uniform B1 field distribution. Non-uniform B1 field distributions can be selected to perform magnetic resonance sequences that use such B1 field distributions, such as parallel imaging. The B1 field distribution can be changed during the magnetic resonance sequence to track a moving region of interest, time division multiplex parallel imaging, and the like.

In a method to optimize a magnetic resonance sequence of a magnetic resonance apparatus, the magnetic resonance sequence includes first imaging parameters that, during acquisition of magnetic resonance images by the magnetic resonance sequence, the first imaging parameters produce acoustic noise with a first acoustic noise volume level and magnetic resonance images with image noise at a first signal-to-image noise ratio. An automatic optimization of the imaging parameters is implemented such that during acquisition of magnetic resonance images by the magnetic resonance sequence, the optimized imaging parameters produce acoustic noise with a second acoustic noise volume level and magnetic resonance images with image noise at a second signal-to-image noise ratio. The second acoustic noise volume is reduced by at least 3 dB relative to the first acoustic noise volume and the second signal-to-image noise ratio is reduced by a maximum of 35 percent relative to the first signal-to-image noise ratio.

The invention discloses a motion correction method for magnetic resonance multiple excitation diffusion imaging. The method comprises the steps of collecting a magnetic resonance multiple excitation sequence; obtaining an image echo signal and a two-dimensional navigation signal through a magnetic resonance scanning sequence; estimating motion parameters through the two-dimensional navigation signal; performing rotational and translational correction on the image echo signal and the two-dimensional navigation signal according to the motion parameters, and discarding tainted data, thereby obtaining corrected data; integrating the corrected data collected in multiple excitation to perform parallel imaging reconstruction; estimating rotational motion parameters through an image registration algorithm to perform diffusion gradient correction on a reconstructed image; and performing final calculation by utilizing corrected diffusion image and diffusion gradient to obtain diffusion tensor imaging parameters. According to the method, various motion errors in a magnetic resonance diffusion imaging scanning process can be effectively corrected, so that an artifact-free high-resolution diffusion tensor image is obtained, the errors are effectively reduced, and the accuracy of calculating magnetic resonance diffusion imaging tensor parameters is improved.

A method and magnetic resonance apparatus for image acquisition using a magnetic resonance sequence (in particular a PETRA sequence) in which k-space corresponding to the imaging area is scanned, with a first region of k-space, which does not include the center of k-space, being scanned radially along a number of spokes emanating from the center of k-space, and with at least two phase coding gradients being completely ramped up before administration of the excitation pulse, and a second central region of k-space, which remains without the first region, is scanned in a Cartesian manner (in particular via single point imaging). For the purpose of a contrast increase a pre-pulse—in particular an inversion pulse to establish a T1 contrast—is provided before a predetermined number of individual measurements. The number of spokes to be measured is selected such that a measurement point located (in a Cartesian manner) nearest to the center of k-space is measured at a predetermined point in time after a pre-pulse, which point in time is optimal with regard to the signal-to-noise ratio and/or the contrast.

In a method for attenuation correction of emission tomography scan data acquired from an examination object in a combined magnetic resonance emission tomography apparatus, wherein an interference object is situated in the examination region, which causes a magnetic interference field during combined magnetic resonance emission tomography imaging, magnetic resonance scan data of the examination object are acquired by executing a magnetic resonance sequence designed to at least partially compensate inference due to the magnetic interference field. Emission tomography scan data are acquired and an attenuation map is generated using the acquired magnetic resonance scan data. Attenuation correction of the emission tomography scan data is implemented using the generated attenuation map.

The invention discloses a bimodal magnetic resonance temperature measurement method based on a multi-gradient echo sequence. The method comprises the following steps: acquiring magnetic resonance signals before and during heating through the multi-gradient echo magnetic resonance sequence, and meanwhile, reserving a phase diagram and an amplitude diagram of each echo; according to the phase diagrams of different echoes before and during heating, calculating temperature changes of each pixel point on the phase diagrams before and after heating, and according to the amplitude diagrams of different echoes during heating, calculating signal intensity of each pixel point when TE is 0; according to the signal intensity of the amplitude diagrams before heating and the signal intensity of each pixel point when TE is 0, calculating temperature change delta T(M) of each pixel point based on an amplitude value; and according to the sum delta T(M), judging final actual temperature T of each pixelpoint or giving out an error warning. According to the temperature measurement method, by synchronous use of the amplitude diagrams and the phase diagrams in multi-gradient echo magnetic resonance temperature imaging, bimodal temperature imaging is realized, and accuracy of magnetic resonance temperature imaging is further improved.

In a method and apparatus for recording a magnetic resonance dataset of at least one foreign body in a target region of a patient, a magnetic resonance sequence having an ultra-short echo time, which is less than 500 μs is used for recording the magnetic resonance data.

In a method for recording magnetic resonance data in a target region of a patient while the target region moves due to respiration a single-shot turbo spin echo sequence is used as a magnetic resonance sequence in a magnetic resonance apparatus. SPAIR fat saturation is used by emitting an inversion pulse at an inversion time before the data recording with the magnetic resonance apparatus. Multiple repetitions of the sequence of an inversion pulse, an inversion time and a data recording using the magnetic resonance sequence are triggered by a respiratory signal describing the respiratory cycle, each repetition occurring upon fulfillment of a recording criterion. At least one further inversion pulse is emitted in a waiting time between the sequences.

In a method and apparatus for setting and/or adjusting a parameter value of at least one parameter of a magnetic resonance protocol for at least one magnetic resonance sequence, a manual entry that selects the magnetic resonance protocol is made into a computer, and a further entry is made that provides boundary conditions for setting and/or adjusting the parameter value of the at least one parameter of the magnetic resonance protocol. The computer provides setting criteria from previous settings and/or adjustments of the parameter value of the at least one parameter of the magnetic resonance protocol. The computer sets and/or adjusts the parameter value of the at least one parameter of the magnetic resonance protocol on the basis of the provided boundary conditions and on the basis of the provided setting criteria.