13 results about "Fast spin echo" patented technology

The invention relates to a magnetic resonance imaging electromagnetic parameter distribution scanning and calculation method, which comprises the following steps that a fast spin echo sequence I is adopted to scan a target body, parameters are (alpha1, TE0, TR0 and Bw1), alpha is a deflection angle, TE is echo time, TR repetition time and Bw receiving bandwidth; scanning a target body by adopting a fast spin echo sequence II, wherein parameters are (alpha2, TE0, TR0 and Bw1); scanning a target body by adopting a fast spin echo sequence III, wherein parameters are (alpha2, TE0, TR0 and Bw2); and scanning the homogeneous water model by adopting the fast spin echo sequences I, II and III. And under the condition that the magnetic vector precession meets the conditions that the amplitudes are comparable when the phases are the same and the phases are differentiable when the amplitudes are the same, each magnetic field and electric field parameter is calculated based on the homogeneous water model data. According to the invention, decoupling of the proton density and the sensitive field of the signal is realized, so that magnetic resonance weighted quantization imaging becomes possible.

Described herein are methods for imaging magnetic resonance imaging (MRI) agents containing nanoconstructs therein using diffusion weighted fast spin echo (FSE) or gradient and spin echo (GRASE) methods.

The invention discloses a single-coil multi-layer parallel magnetic resonance imaging method based on multiple excitation in a low field, and the method comprises the steps: achieving the multi-layer parallel excitation through a multi-band pulse, and carrying out the 0-pi phase modulation of the multi-band pulse; constructing a fast spin echo sequence of secondary phase modulation; performing imaging by using the fast spin echo sequence subjected to secondary phase modulation; and reconstruction is carried out through an odd-even echo classification method, and a scanning result graph is obtained. Aiming at the common problem of low signal to noise ratio of low-field magnetic resonance imaging in practical application, based on hardware characteristics of a single coil of low-field magnetic resonance equipment and actual requirements of repeated scanning, a series of SMS related technologies such as an FSE fast spin echo sequence, Hadamard pulse coding, multi-band pulse and secondary phase modulation are combined; and the signal-to-noise ratio of the low-field FSE sequence is effectively improved.

The present invention provides a method, system, medium, and electronic device for modeling a low-frequency conductivity tensor of the brain. The method includes the following steps: acquiring a phase image of a fast spin echo sequence of the brain; acquiring a high-frequency conductivity image of the brain based on the phase image; acquiring a diffusion-weighted amplitude image of the brain based on a multi-excitation diffusion-weighted sequence; acquiring diffusion microstructure parameters of the brain using a multi-layer model based on the diffusion-weighted amplitude image; generating a low-frequency conductivity tensor image of the brain based on the high-frequency conductivity image and the diffusion microstructure parameters; generating a digital skull model based on a magnetization-prepared fast gradient echo sequence of the brain; and generating a low-frequency conductivity tensor model of the brain based on the low-frequency conductivity tensor image and the digital skull model. The method, system, medium, and electronic device for modeling a low-frequency conductivity tensor of the brain of the present invention provide more accurate target planning for tTIS.

The application provides a small animal sciatic nerve magnetic resonance coil and an imaging method, and the method comprises the following steps: filling a high-concentration sugar syrup solution at the bottom of the magnetic resonance coil and performing constant temperature control; placing a small animal in a prone position in the high-concentration sugar syrup solution and discharging air in the gap between the lower limbs and below the abdomen of the small animal; after performing magnetic resonance positioning scanning to determine the main sequence scanning range, starting the main sequence scanning, suppressing the flow tissue signal through a pre-pulse combination, exciting the tissue by using a radio frequency pulse with preset parameters, acquiring echo signals by combining a fast spin echo technology and filling K space, and obtaining scanning original data; performing preprocessing on the scanning original data and accurate segmentation of the sciatic nerve and spinal nerve to obtain a segmentation result; and completing three-dimensional model reconstruction, optimization and multi-modal fusion visualization based on the segmentation result to obtain an image scanning result. The application is suitable for small animals, is accurate in imaging, can effectively suppress various kinds of artifacts, and can be widely applied to sciatic nerve imaging scenarios of small animals.

A non-localized efficiency shimming technique is used to generate radio frequency (RF) shimming values for imaging with a multi-channel transmit RF coil that minimizes subject-specific imperfections in the transmit magnetic field (B1+) and reduces or eliminates signal dropout in the acquired images, while keeping the coil working in an optimal mode with a high transmit efficiency. The non-localized efficiency shimming can be used for both small and large fields-of-view where a specific ROI does not need to be specified. The static non-localized efficiency shim is advantageous for turbo spin echo (TSE) imaging of smaller anatomical targets, whereas the dynamic non-localized efficiency shim is advantageous for larger fields-of-view, such as in human torsos.

Systems and methods for suppressing image artifacts in multi-shot magnetic resonance (MR) images are disclosed. The techniques described herein include initiating a pulse train for a segment of a multi-shot fast spin-echo imaging procedure by applying an excitation radio frequency (RF) pulse, and transmitting a plurality of RF refocusing pulses for the segment. Each refocusing pulse of the plurality of RF refocusing pulses may have a respective phase that increases by a predetermined phase offset with each successive refocusing pulse of the segment. The techniques include generating k-space data based on a respective plurality of echoes detected by the MR system in response to the plurality of RF refocusing pulses.

The application discloses an infant brain T2 weighted magnetic resonance imaging optimization method based on a fast spin echo sequence. First, T1, T2 and PD quantitative imaging of the infant brain from 0 to 24 months old is collected to obtain T1, T2 and PD values of the infant brain white matter and gray matter regions, and according to the relationship characteristics of the infant brain white matter T2 value and the gray matter T2 value, the infant is divided into different month groups. Then, based on the 3D T2 weighted imaging of the variable flip angle fast spin echo sequence, the signal intensity of the infant brain white matter and gray matter under different refocusing flip angle chains is calculated through an extended phase graph algorithm, and the best flip angle chain design scheme of each group is determined with the maximum white matter / gray matter contrast as the target. The application fills the blank of the infant brain T2 weighted imaging optimization, formulates the best flip angle chain optimization scheme of different month groups, and thus significantly improves the contrast of the infant brain T2 weighted imaging.

The invention relates to a magnetic resonance weighted imaging contrast quantification and relaxation time inversion method, and belongs to the technical field of magnetic resonance imaging. According to the method, human tissues are scanned through three groups of parameter differentiated fast spin echo sequences, interference factors such as equipment characteristics, proton density and deflection angles are eliminated by using parameter relevance among the sequences, a weighted weight is obtained through calculation of an amplitude image ratio, and finally accurate T1 and T2 relaxation values are obtained through inversion. The core innovation of the method lies in that quantification of weighted imaging is realized through scientific design of sequence parameters: ultra-long TR0 and ultra-short TE0 are adopted to construct a reference amplitude image, and an amplitude ratio and relaxation time are directly correlated through mathematical derivation in combination with a moderate comparison sequence of TR1 and TE1. According to the method, the subjective limitation of traditional weighted imaging is broken through, the image detail resolution is higher, the individual evaluation difference and the deviation between equipment can be effectively reduced, and a reliable quantitative basis is provided for early lesion detection, longitudinal curative effect tracking and group data comparison.

In a magnetic resonance imaging method, a first adjustment parameter is determined for presetting an initial contrast of a magnetic resonance image; a second adjustment parameter is determined for obtaining an optimized contrast of the magnetic resonance image and a specified data acquisition time of a blade artifact correction sequence; an optimized echo signal evolution curve is determined according to the first adjustment parameter and the second adjustment parameter; an actual variable flip angle train is calculated according to the optimized echo signal evolution curve; and the actual variable flip angle train is applied to a two-dimensional fast spin echo sequence, and the blade artifact correction sequence corresponding to the second adjustment parameter is used to acquire magnetic resonance signals and enable the magnetic resonance image to satisfy the optimized contrast.

Method for operating a magnetic resonance tomograph for spatially resolved spin resonance measurement of an object, in particular a living object, which is arranged in a static magnetic field B0, whereby an alignment of the object's spins and a longitudinal net magnetization Mz along the direction Z of the static magnetic field results, and wherein a transverse magnetization component Mxy is generated or changed, in particular by generating a spin flip from the Z direction by a desired flip angle, in particular by 90 degrees, by means of at least one high-frequency excitation pulse (1) in spin resonance, wherein spin echo signals from at least one desired volume element of the object are measured using a sequence of high-frequency pulses (4, 5, 7) and switched gradient magnetic fields (2, 3, 6).wherein the at least one volume element is determined by several gradient magnetic fields superimposed at least temporarily on the homogeneous magnetic field B0, wherein the sequence of high-frequency pulses comprises a first (4) and a second high-frequency rephasing pulse (5), in particular a first (4) and second high-frequency rephasing pulse (5) directly after the generation of a transverse magnetization component by means of a high-frequency excitation pulse (1), wherein from the second high-frequency rephasing pulse (5) onwards both a spin echo and a stimulated echo are generated, wherein in addition to a gradient magnetic field (6) in the frequency coding direction, which is switched on during the measurement acquisition to acquire a line of the raw data space, an additional gradient magnetic field (8) in the frequency coding direction is switched on, which generates echo signals or echo signal components newly generated by the high-frequency rephasing pulses (5, 7),in particular, those not attributable to a refocusing of the original spin echo after the first radio frequency rephasing pulse (4) and / or of the original stimulated echo after the second radio frequency rephasing pulse (5), are shifted out of the raw data space or raw data line acquired in a subsequent measurement, characterized in that, during an evolution time (Tau) between the first (4) and second radio frequency rephasing pulse (5), T2*-induced relaxation processes act on a transverse magnetization component present after the first radio frequency rephasing pulse (4), and a magnetization component present in the longitudinal direction after the first radio frequency rephasing pulse (4) remains unaffected, wherein the absolute time between the first (4) and second radio frequency rephasing pulse (5) is extended by the evolution time beyond the duration of an echo interval,which is present between subsequent equidistant high-frequency rephasing pulses (5, 7).

Disclosed herein is a method of imaging at least a part of a subject (318). The method comprises receiving (200) k-space data (122) acquired according to a fast spin echo magnetic resonance imaging protocol. The method further comprises reconstructing (202) an initial magnetic resonance image (124) from the k-space data. The method further comprises receiving (204) a free induction decay artifact image (128) in response to inputting the initial magnetic resonance image into an image processing neural network (126). The image processing neural network is configured for filtering free induction decay artifacts from fast spin echo magnetic resonance images. The method further comprises generating (206) a clinical magnetic resonance image (130), through a combination of at least a portion of the free induction decay artifact image and the initial magnetic resonance image. The method further comprises providing (208) the clinical magnetic resonance image.

A computer-implemented method for operating a magnetic resonance device for acquiring magnetic resonance data is provided. The method may include providing (e.g., determining) a three-dimensional, slab-selective turbo spin echo sequence having at least one echo train is used, each echo train comprising an excitation module with an excitation pulse preceding a readout module. The readout module may include multiple refocusing pulses and associated readout intervals. The excitation pulse may be at least partly implemented as a variable rate selective excitation pulse. The readout module may immediately succeed the excitation module.