10 results about "Flip angle" patented technology

In a method for improving the recording of measurement data of an object under inspection, the method includes loading desired imaging parameters and a desired flip angle for recording the measurement data by means of a recording method, wherein the gradient to be switched for position encoding of the measurement data has its full intensity during the incident RF excitation pulse. A quantization value of a desired interference for the recording method is determined based on the desired imaging parameters, and a check on the feasibility of correcting for the interference is performed based on the quantization value and the desired flip angle.

This invention discloses a high signal-to-noise ratio (SNR) magnetic resonance (MRI) data acquisition method, signal processing method, and system, belonging to the field of MRI technology. The invention aims to maximize the image SNR while maintaining spatial resolution by simultaneously optimizing the radio frequency flip angle sequence of the echo train and the k-space filtering weights through a joint optimization framework. This invention can obtain high-quality MRI images, fundamentally improving the image quality of FSE sequences.

This application discloses a signal readout method and apparatus based on a Hall effect device array with lateral resistance, relating to the field of circuit technology. Each Hall effect device is provided with two power supply terminals and at least one Hall signal terminal. The method includes: changing the flip angle of the free magnetic layer of at least one Hall effect device using spin orbital moment, thereby setting the Hall resistance value of the corresponding Hall effect device to a desired target value; connecting the Hall signal terminals of several Hall effect devices in series to read the summed voltage; and connecting the Hall signal terminals of several Hall effect devices in parallel to read the summed current. The Hall effect device of this application can achieve current-induced out-of-plane magnetization reversal under shunt conditions; the flip angle can change the resistance value, thereby reducing the need for Hall effect devices with different resistance values; this application realizes that the Hall signal terminals of multiple Hall effect devices are connected in series to achieve voltage summation, or connected in parallel to achieve current summation.

A spectrum measurement method and apparatus in nuclear magnetic resonance, a device, and a storage medium. A target sample is arranged in a uniform magnetic field, a target direction of the target sample is consistent with the uniform magnetic field, a gradient coil is arranged on the target sample, and the method comprises: applying a linear gradient magnetic field in the target direction of the target sample; determining a uniform region of a radio frequency coil on the basis of a bandwidth of a radio frequency pulse signal; during reception of a nuclear magnetic resonance echo signal, adjusting the magnitude of the linear gradient magnetic field under the condition of a target flip angle until a region of the nuclear magnetic resonance echo signal is constrained within the uniform region of the radio frequency coil to obtain a target linear gradient magnetic field; obtaining a target nuclear magnetic resonance echo signal on the basis of the target linear gradient magnetic field; and performing inversion on the target nuclear magnetic resonance echo signal to obtain a T1-T2 spectrum. The problem of T1‑end tailing caused by conventional T1-T2 measurements is solved, thereby greatly improving the measurement accuracy.

A method for magnetic resonance imaging is provided herein. The method includes acquiring magnetic resonance data from a subject using a magnetic resonance imaging (MRI) system to sample a hybrid space along a zigzag trajectory. The hybrid space comprises a first axis along a temporal dimension and a second axis along a phase-encoding k-space dimension. The data acquisition involves, for each slice of a plurality of slices, consecutively acquiring all shots of a multi-shot acquisition for the slice before acquiring data for a next slice, with each shot using a radio frequency (RF) excitation pulse having a different flip angle. The method further includes reconstructing images from the acquired magnetic resonance data.

The application discloses a kind of 3D multi-parameter simultaneous quantification of magnetic resonance imaging method including myelin water, comprising: initialization includes two T2 preparation pulse and five readout section magnetic resonance quantification sequence;Using optimization model based on Cramer-Rao lower bound and self-supervised multilayer perception, flip angle, echo time and interval time of sequence are jointly optimized;Signal dictionary is constructed using optimized parameter and the base of subspace is extracted;Original k-space data is collected to reconstruct the timing of subspace and obtain timing reconstruction image;Finally, timing signal is matched with dictionary, and T1, T2 and MWF quantitative map of whole brain are generated.The application breaks the limitation of traditional experience parameter setting, significantly improves the quantification accuracy of short T2 myelin water and conventional tissue parameters, and realizes single whole brain high-resolution multi-parameter simultaneous quantification in 3 minutes 30 seconds, greatly shortens the scanning time, and greatly improves the clinical applicability.

The application discloses a magnetic resonance sequence parameter joint optimization method based on Cramer-Rao lower bound, which comprises two parts of multilayer perception network construction and joint loss function setting. The Cramer-Rao lower bound is obtained based on preset biological tissue parameters and network output optimization parameters to form a CRLB loss term, and a time penalty term related to the total time length of sequence acquisition is constructed based on the recovery interval time. The network is iteratively trained by minimizing the joint loss function composed of the CRLB loss term and the time penalty term, and the optimization parameters finally output by the network model are combined for scanner sequence setting to complete imaging. The application realizes efficient joint optimization of flip angles and key timing parameters without a large number of physical scanning tests, reduces the acquisition time length while ensuring or improving the accuracy of quantitative parameter maps, and the optimized parameters can reduce the number of readout sections of the magnetic resonance sequence, thereby realizing the reduction of the scanning time.

The application is suitable for the technical field of image processing, and provides a magnetic resonance imaging method, a terminal device and a computer readable storage medium, comprising: acquiring an optimization function; wherein the optimization function is a function constructed according to a point spread function, and the point spread function is used for describing the energy distribution of signals in an image domain; the optimization function is used for constraining the energy of an energy lobe in a distribution curve corresponding to the point spread function; optimization of a flip angle sequence is performed according to the optimization function to obtain a target flip angle sequence; and an imaging device is controlled to perform scanning according to the target flip angle sequence to obtain a target magnetic resonance image. Through the above method, the magnetic resonance imaging effect can be improved.