10 results about "Longitudinal Relaxation Time" patented technology

The present application relates to a kind of cardiac magnetic resonance longitudinal relaxation time measurement method, medium and equipment.The measurement method includes the following steps: S1 uses MOLLI sequence respectively before and after scanning contrast;Specifically, in the before and after scanning contrast, by setting different initial inversion time TI, setting 3 groups of LL experiment LL1, LL2, LL3 triggered by continuous ECG, enough relaxation curve sampling points are obtained after fusion;And data is collected at the end of diastole of cardiac cycle, and 1 image is obtained per heartbeat;S2 image processing.This measurement method can realize single-pixel high-resolution T1 mapping under the breath holding of selection data acquisition and multi-LL experiment data fusion, give consideration to high accuracy, high resolution and high efficiency, and have good compatibility and practicality, provide new scheme for early diagnosis of heart disease, lesion quantification and prognosis evaluation, have wide clinical application prospect.

The invention discloses a low-field NMR relaxation time rapid measurement method, and the method comprises the steps: designing an IR-bSSFP pulse sequence which comprises a 180-degree reversal pulse and an excitation pulse sequence, and enabling the flip angle of a radio frequency excitation pulse in the excitation pulse sequence to be a pseudo-random flip angle; the radio-frequency phases of the adjacent radio-frequency excitation pulses are linearly changed by a fixed phase increment; based on the IR-bSSFP pulse sequence, obtaining a component MRF signal sequence of a measured object, and simulating a magnetization vector evolution process to obtain a dictionary matrix; matching the component MRF signal with a dictionary matrix pattern in combination with a smooth constraint term to obtain corresponding longitudinal relaxation time and transverse relaxation time; the invention also discloses low-field NMR relaxation time rapid measurement equipment, which comprises a pulse sequence construction module, a dictionary generation module and a mode matching module. Multi-parameter information can be obtained through single scanning, the measurement time is remarkably shortened, the experiment complexity is reduced, and the precision and repeatability of a measurement result are improved.

A method for generating a property representation of a substance is described. The method comprises: obtaining portions of one or more nuclear magnetic resonance (NMR) data of the substance, where each NMR data portion comprises one or more NMR datasets, each NMR dataset comprising intensity data and relaxation data; processing each NMR data portion into a multi-dimensional distribution of a fitting data set by performing a plurality of fits of a function, where the function includes at least 3 fitting parameters; and generating a characteristic representation of the substance from the fitting data set. The processing includes applying at least one initial guess value. Each set of fitting data comprises data embedded with at least one subset of fitting data comprising an apparent longitudinal relaxation time (T1 *), an associated apparent transverse relaxation time (T2 *) and an associated intensity (M0), preferably said function being a function of a model representing the obtained NMR data portion.

The invention provides a magnetic resonance parameter determination method and device, electronic equipment and a computer program product, and the method comprises the steps: scanning a scanning object through employing a plurality of gradient echo sequences of different repetition times, and obtaining a magnetic resonance image corresponding to the gradient echo sequence of each repetition time; the radio frequency flip angles set by the plurality of gradient echo sequences are the same; performing nonlinear fitting according to a plurality of different repetition times, a radio frequency flip angle set by the gradient echo sequence, the signal intensity of each magnetic resonance image and a preset signal model to determine a longitudinal relaxation time constant, the independent variables of the signal model including the repetition time and the longitudinal relaxation time constant, the dependent variable of the signal model is the signal intensity of the magnetic resonance image. Therefore, the gradient echo sequences with the same flip angle and different repetition times are adopted for scanning, and nonlinear fitting is performed based on the steady-state signal model, so that the longitudinal relaxation time constant can be quickly and accurately determined without long waiting time.

The invention belongs to the technical field of nuclear magnetic resonance gyroscopes, and relates to a device and a method for measuring longitudinal relaxation time of a miniaturized atomic air chamber. The measuring device comprises: a miniaturized atomic gas cell; the pumping light and light path structure comprises a pumping light laser, a pumping light polarizer, a quarter-wave plate and a light absorption black body which are sequentially arranged along the Z axis; the detection light and light path structure comprises a detection light laser, a detection light polarizer, a half-wave plate, a first right-angle prism reflector, a second right-angle prism reflector, a polarization splitting prism, a first photoelectric detector and a second photoelectric detector which are sequentially arranged along a detection light path; the temperature control system comprises non-magnetic heating devices arranged on the two sides of the miniaturized atomic gas chamber and a temperature control circuit; the magnetic field control system comprises a double-layer magnetic shielding cover, a three-axis magnetic field coil arranged on the outer side of the miniaturized atomic gas chamber, and a magnetic field control circuit; and the signal processing system performs fitting calculation on the longitudinal relaxation time.

The application discloses an optimization method, device, equipment and medium for magnetic resonance imaging, and relates to the field of magnetic resonance imaging. The method comprises the following steps: acquiring a reference longitudinal relaxation time of an imaging magnetic resonance device with a preset main magnetic field strength; constructing a linkage fitting function between TR and TI parameters based on the reference longitudinal relaxation time, taking the maximum difference value between an image signal of a hemorrhagic focus and an image signal of healthy brain parenchyma as a target; determining a target TI according to a target TR and the linkage fitting function; optimizing scanning parameters of the magnetic resonance device by using a minimum effective echo time, the target TR and the target TI; acquiring an initial magnetic resonance image, which is obtained by scanning a stroke patient by using the magnetic resonance device with the optimized parameters; and enhancing the initial magnetic resonance image by using a nonlinear stretching function to obtain a stroke triage enhanced inversion recovery image. The application can improve the image contrast of the magnetic resonance imaging.

The application relates to the technical field of magnetic resonance imaging, and provides an ASL perfusion imaging method, device and system based on multi-parameter magnetic resonance measurement, which comprises the following steps: determining a first parameter based on first magnetic resonance measurement data; determining a second parameter based on second magnetic resonance measurement data; determining a third parameter based on third magnetic resonance measurement data; determining a labeling delay time of ASL perfusion imaging based on the first parameter, the second parameter and the third parameter; and performing ASL perfusion imaging based on the labeling delay time. The first parameter comprises blood vessel path length information, the second parameter comprises blood flow velocity information, and the third parameter comprises blood longitudinal relaxation time. The application does not need to prolong the examination time, can match more suitable labeling delay time for different subjects, and improves the accuracy of the examination result.

The invention discloses a method and a device for determining a flow velocity metering upper limit of a magnetic resonance flowmeter. The method comprises the following steps: acquiring field intensity distribution data of a plurality of measurement points of the magnetic resonance flowmeter from the starting position of a probe to the center of an antenna, and acquiring the maximum amplitude of an echo signal and the maximum amplitude of noise measured by putting the probe into static pure water; based on the field intensity distribution data and the maximum amplitude of the echo signal, determining a first magnetization vector when the fluid flows to the antenna according to the set flow velocity and the longitudinal relaxation time of the measured fluid; according to the first magnetization vector and the longitudinal relaxation time of the fluid, determining a second magnetization vector attenuating for a set time after the fluid reaches the antenna; whether the difference value between the second magnetization vector and the maximum amplitude of the double noise is smaller than a set difference value or not is judged; if yes, determining the current speed as the upper limit of the flow velocity measurement of the flow meter on the fluid; and if not, modifying the current speed. According to the method, the measurable flow velocity upper limit of the magnetic resonance flowmeter facing different working conditions can be conveniently determined.

The invention provides a methane occurrence state quantitative analysis method for accurate resource evaluation of deep coal bed gas, which comprises the following steps: firstly, collecting a two-dimensional nuclear magnetic resonance spectrogram of a coal sample adsorption test, carrying out gridding processing on two-dimensional nuclear magnetic resonance spectrogram data of the coal sample adsorption test, and establishing a two-dimensional signal matrix; then, according to the distribution characteristics of the longitudinal relaxation time T1 and the transverse relaxation time T2, dividing the spectrogram into four regions, namely a single-layer adsorption state, a filling adsorption state, an inter-pore free state and an inter-cavity free state; and finally, carrying out point-by-point summation on the signals of each region, and converting a value obtained after signal intensity summation into a gas content model so as to obtain the quantitative content of methane in different occurrence states. According to the method, clear distinguishing between single-layer adsorption and filling adsorption can be achieved, the law that the occurrence state of adsorption and free methane evolves along with pressure can be revealed, and the technical problem of accurately determining the in-situ occurrence state of deep coal bed gas, which puzzles the deep coal bed gas industry for a long time, is solved.

The invention relates to a longitudinal relaxation time constant acquisition method and device and a magnetic resonance imaging system. The method comprises the following steps: acquiring a plurality of amplitude images corresponding to a plurality of inversion recovery moments; adjusting the plurality of amplitude images according to a first deviation value of the amplitude in each amplitude image; and obtaining a longitudinal relaxation time constant of a target position point in the amplitude image according to the multiple adjusted amplitude images and the corresponding inversion recovery moments. By adopting the method, the problem of low accuracy of a longitudinal relaxation time constant fitting result can be solved.