81 results about "Fast spin echo" patented technology

The invention provides a method for correcting fast spin echo sequence, aiming at solving the problem that the prior FSE images have the factors of an imaging system such as artifacts, magnetic field stability, eddy current, etc. which have impact on the quality of images. The method can be used to correct the parameter of the fast spin echo (FSE) sequence of a magnetic resonance diagnostic, in particular to correct the parameter of the fast spin echo (FSE) sequence of a magnetic resonance diagnostic which can switch frequence of a transmitter and a receiver. The method for correcting fast spin echo sequence of the invention eliminates the impact of the factors of the imaging system such as artifacts, magnetic field stability, eddy current, etc. on the quality of the images; and as the parameter which is obtained by the correcting method and used in the pre-scanning is the optimal parameter, thereby solving the problem of artifacts of the prior FSE images.

A receiver for a resonance signal of a magnetic resonance imaging system generates a baseband signal for image processing by dividing a raw resonance signal among multiple parallel channels, each amplified at a respective gain. A digital channel selector determines, at any given moment, a lowest-distortion channel to be further processed. Amplitude and phase error compensation are handled digitally using complex multipliers, which are derived by a calibration, based on a simple Larmor oscillator, which can be done without the need for a sample and without repeating when measurement conditions are changed. One of the important benefits of the invention is that it provides for gain selection without repeated calibration steps. This is particularly important in systems that employ fast imaging techniques such as fast spin echo, where the invention can speed imaging substantially.

The invention provides a gradient system time delay correction method for a fast spin echo pulse sequence. In the method, a gradient system time delay is corrected by correcting a gradient pulse, and an amplitude synthetic matrix for correcting the gradient pulse is calculated by using the normalized gradient system time delay. By the method, the influence of the gradient system time delay on thefast spin echo pulse sequence is overcome, and the hardware cost and the system complexity of a magnetic resonance imaging system are not increased; and even if the gradient system time delays in x, y and z directions are unequal, the power of a gradient power amplifier is not enough to provide overshooting impulse with larger amplitude in a gradient waveform. By the method, the gradient system time delay can still be corrected so as to enhance the image quality of a sagittal plane, a coronal plane, a cross section and various diagonal planes in a fast spin echo image.

The invention relates to the field of magnetic resonance imaging technique, in particular to a magnetic resonance fast spin echo (FSE) imaging method, comprising the steps as follows: 1. phase coding gradient amplitude is reset, pre-scanning is carried out by FSE pulse sequence, the amplitude value of each etch signal peak on the echo chain is recorded; 2. the phase and inclination angle of convergence pulse is adjusted so as to lead the amplitude of each echo signal peak on the echo chain to achieve the maximum value, when the amplitude value Am and phase angle Phim of each echo signal peak are recorded; 3. the phase coding gradient is recovered, the scanning is carried out by the FSE pulse sequence, thus gaining the K space data; 4. according to the amplitude Am and Fai<m> of each echo signal peak gained in step 2, the K space data is corrected; 5. image reconstruction is carried out by the corrected K space data thus gaining the magnetic resonance images, etc. The magnetic resonance fast spin echo (FSE) imaging method solves the problems of echo amplitude phase oscillation and image blurring due to transverse relaxation of the prior art.

A method to separate two chemically-shifted components of water (w) and fat (f) signals by: (i) estimating the field inhomogeneity β through a treatment of the residuals of the Moore-Penrose solution of the following equations: cos(α_nβ)*w+cos [α_n(1+β)]*f=real (I_n) and sin(α_nβ)*w+sin [α_n(1+β)]*f=imaginary (I_n), and (ii) using the estimated β to determine the resulting solution for w and f from the original input signals I_n.

The present invention aims to reduce degradation in image quality due to residual magnetization. In a pulse sequence of a high-speed spin echo process, a pre-pulse is applied before an excitation pulse, and a correction pulse for correcting a phase error caused by the pre-pulse is applied before an initial inversion pulse.

Exemplary embodiments of system, method and computer-accessible medium can be provided in accordance with the present disclosure can be provided for generating a plurality of images associated with at least one anatomical structure using magnetic resonance imaging (MRI) data. For example, using such exemplary embodiments, it is possible to obtain at least one multi-echo fast spin-echo (FSE) pulse sequence based on the MRI data, which can include, e.g., hardware specifications of the MRI system. Further, it is possible to generate each of the images based on a particular arrangement of multiple echoes produced by the multi-echo FSE pulse sequence(s).

The invention relates to a medical image processing method which is characterized in that images formed by three-dimensional fast spin echo imaging collected by a magnetic resonance imaging system in the focus area of a patient and blood vessel images collected by a digital subtraction angiography machine are subjected to reconstruction, color inverting, cutting, 3D-3D fusion and 3D-2D registering through a post-processing work station of the digital subtraction angiography machine, so that three-dimensional blood vessel graphs can be overlapped on a real-time radio-fluoroscopic image. Therefore, by adopting the medical image processing method, real-time imaging guide can be performed during nerve involvement surgeries for blocked blood vessels, the near end and far end of the closed section of the blood vessel can be shown simultaneously through imaging, and physicians can clearly get known of conditions in the focus areas and further can perform operating better.

Exemplary systems, methods and computer-accessible mediums can be provided for imaging at least one anatomical structure. For example, it is possible to direct a saturation-recovery (SR) pulse sequence having fast spin echo (FSE) to or at the anatomical structure(s). At least one T₁ image of the at least one anatomical structure can be generated based on the SR pulse sequence. In one example, the anatomical structure(s) can include a hip. According to another example, T₁ image(s) can include a plurality of T₁ images generated or provided in a plurality of rotating radial planes.

An NMR imaging process utilizes both driven equilibrium and fast-spin echo techniques to acquire image data. The fast-spin echo technique is a multi-echo imaging sequence, where a 90-degree RF pulse applied at the center of any echo turns the magnetization back in the direction of the static magnetic field. Within a short waiting time after that pulse, the spins are ready to be excited again. The sequence follows a first 90-degree RF pulse by a series of n 180-degree RF pulses, followed by n echoes. A second 90-degree RF pulse applied to the nth echo returns the magnetization. A multiple single-slice mode is utilized to acquire individual slice images one at a time. A continuous single-slice mode is utilized to acquire individual slice images automatically in sequence over the region of interest. In either mode, adjacent slices can be made to overlap to a degree ranging from 0% to 100%.

A method and a device are provided that improve quantification of the spin-spin relaxation (“T₂”) time of an image in nuclear magnetic resonance (“NMR”) applications using fast multi spin-echo sequences. The method employs time-efficient computer simulations for exact modeling of spurious stimulated echoes in multi-dimensional magnetic resonance imaging (“MRI”) runs. The method employs Bloch simulations and can use a plurality of parameters to produce echo modulation curves prior to correcting distorted experimental data based on pre-calculated simulation values.

An NMR imaging process utilizes application of both a driven equilibrium technique and a fast-spin echo technique to acquire image. The fast-spin echo technique is a multiecho NMR imaging sequence, where different echoes are encoded differently to fill the (k_x, k_g) space at a speed of 1/n of the single echo speed, where n is the number of echoes in the multiecho sequence. During this echo train, a 90-degree RF pulse applied with proper phase at the center of any echo turns the magnetization back in the direction of the static magnetic field. Within a short waiting time after the 90-degree RF pulse, the spins are ready to be excited again. The multi-echo sequence has one 90-degree RF pulse at the beginning, followed by a series of n 180-degree RF pulses, followed by n echoes. A second 90-degree RF pulse is turned on exactly at the center of the nth echo, which returns all the magnetization left at this time to the static field direction. Only one frequency is used for excitation in acquiring the NMR signal in the single slice mode. Gradients are adjusted for oblique scanning. In the multislice acquisition mode, RF phases of different slices are different from one another and the final images can be constructed either by sharing the k_g space or by using a transform process to separate the slices.

The invention discloses a flow compensation method for a nuclear magnetic resonance imaging system. The flow compensation method is characterized by comprising the following steps that: (1) gradient combined pulses which satisfy flow compensation are applied in a frequency encoding direction between a 90-degree radio frequency pulse time series and a 180-degree radio frequency pulse time series of a fast spin echo (FSE) sequence; (2) a scattering gradient is applied before a signal acquisition gradient and before 180-degree radio frequency pulses, and a compensation gradient is applied after the acquisition gradient, and the signal acquisition gradient, the scattering gradient and the compensation gradient jointly form a first-order gradient velocity compensation gradient; (3) phase encoding gradient amplitude is set to be zero, and the time series of the sequence is set, and the amplitudes of the gradients are adjusted, and the amplitude of echo signal peaks of an echo chain is made to reach a maximum value, and the debugging of the sequence is completed; and (4) the sequence is outputted to a spectrometer, so that flow compensation can be realized. With the flow compensation method for the nuclear magnetic resonance imaging system of the invention adopted, situations such as cerebrospinal fluid flow and spinal fluid flow artifacts and image blurring can be significantly inhibited, and therefore, the problem of image artifact generation which is caused by physiological movement such as blood flow or periodic movement can be alleviated.

An NMR imaging process includes subjecting an imaging object to a uniform polarizing magnetic field. Orthogonal magnetic field gradients are applied to the imaging object. RF energy is applied to the imaging object. The RF energy includes a plurality of angular precession frequencies simultaneously applied to correspond to a respective plurality of selected slices of the imaging object. A corresponding plurality of nuclear magnetic resonance signals emitted by the imaging object are simultaneously detected. The nuclear magnetic resonance signals are processed to provide diagnostic information related to individual ones of the plurality of selected slices. In this way, multiple slices are excited and sampled simultaneously. The RF energy can be applied by applying RF energy to the imaging object according to a fast-spin echo technique and subsequently applying RF energy to the imaging object according to a driven equilibrium technique.

The invention applies to the technical field of magnetic resonance and provides an MRI (magnetic resonance imaging) method and device. The MRI method comprises the following steps: establishing an MRI sequence acquisition model for positive contrast of FSE (Fast spin echo) acquired parallelly by multiple-channel coils; establishing a joint estimation model according to a magnetic susceptibility map and a structure image; acquiring MRI data according to the joint estimation model in combination with the MRI sequence acquisition model so as to reconstruct an MRI image. With adoption of the method, the positional relation between an intervention device and surrounding tissue can be recognized clearly, intraductal condition of a stent device is evaluated, the imaging resolution is higher, the imaging speed is higher, and the signal-to-noise ratio is higher.

The invention relates to a magnetic resonance vessel wall imaging method and an apparatus. The method comprising: applying a set of radio frequency pulse sequences to an imaging area, wherein the setof radio frequency pulse sequences includes, in chronological order, a composite double-band delay alternation and a custom excitation nutation A DANTE pulse group, a variable flip angle chain of a three-dimensional fast spin echo SPACE, and a flip down radio frequency pulse chain (S110); acquiring a magnetic resonance signal generated by the imaging area and reconstructing a magnetic resonance signal to obtain the imaging area Magnetic resonance image of blood vessel wall (S120). By further inverting the cerebrospinal fluid signal of the whole brain by increasing the downward flip of the radio frequency pulse chain after the variable flip angle chain of the three-dimensional fast spin echo SPACE, the use of the DANTE pulse group can help the vascular wall at the head-neck joint Imaging.

The invention discloses a carp brain electrode implantation method by means of magnetic resonance positioning and navigation. Taking the first fish scale (the junction of the head and the trunk) as the origin, reference scratches are made on the surface of the skull based on the characteristics of the carp skull to establish Space coordinate system; with the help of the T2WI fast spin echo scanning sequence of the magnetic resonance equipment, the brain is scanned and imaged, the two-dimensional coordinates of the electrode stimulation site are converted into three-dimensional space coordinates, and the spatial coordinates of the brain stimulation electrode implantation site are determined The coordinate value of the system; according to the coordinate value, the brain stimulation electrode is implanted for positioning and navigation. The invention can not only locate and navigate for the implantation of the carp aquatic animal robot brain stimulation electrodes, but also provide new positioning and navigation means for the implantation of various animal robot brain stimulation electrodes.

The invention provides a method for optimizing radio frequency pulses in a fast spin echo pulse sequence. According to the method, spin echoes and stimulated echoes are separated by utilizing the difference of the action of a disturbed phase gradient on the spin echoes and the stimulated echoes, and the stimulated echoes or the spin echoes disappear through reverse pulses with different tilt angles, so that independent adjustment of the spin echoes and the stimulated echoes is realized; and the phase of the reverse pulse is optimized by using the relationship among the spin echoes, stimulatedechoes and reverse pulses in phase. According to the method, the influence of radio frequency field heterogeneity on the FSE sequence parameter optimization process can be reduced, the radio frequencypulse optimization efficiency is improved, and the method is particularly suitable for a high-field magnetic resonance imaging system.