98 results about "Longitudinal Relaxation Time" patented technology

The invention discloses a nuclear magnetic resonance analyzer and a nuclear magnetic resonance measuring method. The analyzer comprises a radio frequency circuit, a magnet, a glass tube, a first coil and a second coil, wherein a sample to be measured is placed in the glass tube; the glass tube is fixedly arranged at a position opposite to the magnet and is placed in a magnetic field produced by the magnet; the first coil and the second coil are wound on the outer surface of the glass tube respectively and are connected with the radio frequency circuit; the first coil is placed at a uniform magnetic field produced by the magnet; and the second coil is placed at a gradient magnetic field produced by the magnet. Through the analyzer, distribution data of transverse relaxation time and longitudinal relaxation time of substances in the sample to be measured can be obtained, and distribution data of diffusion coefficients of the substances in the sample can be obtained.

A method and apparatus for obtaining a parameter of interest relating to a region proximate a nuclear magnetic resonance (NMR) logging tool suitable for subterranean well logging is disclosed. The nuclei of the region are subjected to a pulsed NMR technique and are productive of NMR logging data, the nuclei of the region characteristically having a longitudinal relaxation time T₁ distribution and an apparent transverse relaxation time T_2app distribution. In response to the NMR logging data, an R distribution is defined as R=T₁/T_2app, the T_2app and R distributions are processed as separate bins, along with the NMR logging data, according to a two-dimensional inversion model, and a signal intensity map of R versus T_2app is provided that is representative of the parameter of interest relating to the region. In response to a high-intensity signal on the map being within a first range of T_2app values and a first range of R values, the presence of a light hydrocarbon within the region is identified.

A method for determining a property of a flowing fluid by nuclear magnetic resonance includes applying a static magnetic field to the flowing fluid; acquiring a suite of nuclear magnetic resonance measurements on the flowing fluid using a pulse sequence comprising a spoiling pulse, a wait time, and an acquisition pulse sequence, wherein the suite of nuclear magnetic measurements have different values for the wait time; and fitting the suite of nuclear magnetic resonance measurements to a forward model for responses of the flowing fluid to derive a parameter selected from a flow speed, longitudinal relaxation times of the flowing fluid, and a combination thereof.

Methods and pulse sequences for facilitating nuclear magnetic resonance (NMR) measurements in grossly inhomogeneous fields. Methods and pulse sequences according to the invention may be used to accurately measure variables such as transverse relaxation time, longitudinal relaxation time, and diffusion, without the need for data at long recovery time, thereby allowing for faster measurements. In addition, methods and pulse sequences according to embodiment of the invention may allow simultaneous encoding of information in both the amplitude and the shape of echoes, so as to allow a single-shot measurement of multiple variables, e.g., both transverse relaxation time (from the decay of echo amplitudes) and longitudinal relaxation time (from the echo shape). CPMG detection may be used to overcome the often limited signal-to-noise ratio in grossly inhomogeneous fields.

This document discusses, among other things, a system and method for modulating transverse and longitudinal relaxation time contrast in a rotating frame based on a train of radio frequency pulses.

An MR imaging system independently manipulates a fat and a water component of MR signals used for generating image data. An RF signal generator and a magnetic field gradient generator provide an RF pulse and magnetic field gradient sequence for acquisition of an MR signal discriminating between anatomical objects based on longitudinal relaxation time (T1). The sequence comprises, a first pulse sequence for selectively inverting a water component of the MR signal substantially exclusively of fat, a first time delay adjustable to discriminate between different anatomical elements, a second pulse sequence having a resonant frequency selected to invert a fat component of the MR signal substantially exclusively of water and a data acquisition magnetic field gradient for acquisition of the MR signal. An image shows enhanced visualization of discriminated anatomical elements.

An amplitude of an echo signal in a driven equilibrium (DE) pulse group is used for determination of a longitudinal relaxation time T₁ of an earth formation. DE pulse groups followed by a CPMG sequence can be used for estimating both T₁ and a transverse relaxation time T₂ within one fast measurement.

An MRI apparatus is disclosed, the MRI apparatus comprising a computer programmed to apply a fluid suppression technique prior to an imaging pulse-gradient sequence, wherein the fluid suppression technique is configured to suppress signals from fluids having long longitudinal relaxation times, and apply a fat suppression technique after the fluid suppression technique and prior to the imaging pulse-gradient sequence, wherein the fat suppression technique is configured to suppress fat signals. The computer is further programmed to apply a flow suppression preparation sequence after the fat suppression technique and prior to the imaging pulse-gradient sequence, wherein the flow suppression preparation sequence is configured to suppress moving tissue signals. The computer is also programmed to apply the imaging pulse-gradient sequence, cause the RF transceiver system to acquire MR signals during the imaging pulse-gradient sequence, and reconstruct an image from the acquired MR signals.

The invention provides a petroleum reservoir rock constituent identification and quantitative evaluation method. The method comprises the steps that nuclear magnetic resonance response signals of sample rocks are received, and inversion is performed on the response signals so that a first spectrogram is acquired; aperiodic relaxation time T2sec and the specific value T1/T2 of longitudinal relaxation time T1 to transverse relaxation time T2 are calculated according to the first spectrogram, and the first spectrogram is projected to a coordinate system with the specific value T1/T2 of longitudinal relaxation time T1 to transverse relaxation time T2 and aperiodic relaxation time T2sec acting as coordinate axes so that a second spectrogram is formed; and locating areas of different hole types are divided on the second spectrogram according to the preset cut-off value, and the proportion of each hole type is obtained via an integration method. According to the petroleum reservoir rock constituent identification and quantitative evaluation method, accuracy of reservoir rock constituent identification and reliability of the reservoir quantitative evaluation result can be enhanced.

A method for determining an earth formation property from nuclear magnetic resonance measurements includes applying suppression functions to spin echoes in at least one burst measurement set to produce a modified burst data set, the suppression functions to suppress contribution of spin echoes having non-negligible polarization correction; inverting the modified burst data set and at least one standard spin echo measurement set to produce a nuclear magnetic resonance parameter distribution, the at least one standard spin echo measurement set and the at least one burst measurement set being acquired on an earth formation sample; and computing the earth formation property from the nuclear magnetic resonance parameter distribution. The nuclear magnetic resonance parameter includes at least one selected from longitudinal relaxation time, transverse relaxation time, a ratio of longitudinal relaxation time to transverse relaxation time, and diffusion constant.

The embodiment of the invention discloses a synchronous monitoring method, apparatus and device for tissue displacement and temperature and a storage medium. The method includes the steps that when asequence in a magnetic resonance sound radiation power image MR-ARFI meets the condition that the ratio of echo time to transverse relaxation time is smaller than a preset first threshold value and the ratio of repetition time to longitudinal relaxation time is greater than a preset second threshold value, tissues are scanned based on MR-ARFI technology to obtain a tissue image; according to an image amplitude at the current moment, the accumulated phases of the image at all moments and the image amplitude at the initial moment and the tissue temperature, the tissue displacement and temperature at the current moment are monitored synchronously. By adopting the technical scheme of the embodiment of the present invention, the displacement and temperature of the tissue at the current moment can be synchronously monitored, and the safety of the FUS focusing process is ensured.

The invention relates to a method for determining the conversion rate of polyisobutylene, in particular to a method for determining the conversion rate of the polyisobutylene during a process of generating p-polyisobutylene phenol through reaction of the polyisobutylene and excessive phenol through a quantitative nuclear magnetic resonance spectroscopy. The method comprises the steps of respectively acquiring a polyisobutylene phenol sample, and a polyisobutylene and phenol nuclear magnetic resonance spectroscopy, obtaining chemical shift of the p-polyisobutylene phenol through spectrogram comparison and spectrogram reasoning; determining longitudinal relaxation time T1 of a p-polyisobutylene phenol sample in a deuteration reagent, setting a pulse flip angle and relaxation time of a nuclear magnetic resonance spectrometer according to the T1, utilizing the nuclear magnetic resonance spectrometer for determining the nuclear magnetic resonance spectroscopy of a solution to be tested, obtaining a peak area of each part of hydrogen through integration, and calculating to obtain the conversion rate of the polyisobutylene through the number of hydrogen actually contained in a target product and raw materials. The method provided by the invention is low in cost, can be used for quickly and accurately evaluating the type and the conversion rate of a synthetic product of the polyisobutylene and the phenol, and provides a powerful evidence for synthesis.

The invention provides a prostate magnetic resonance image segmentation method based on a level set and relates to the technical field of magnetic resonance image segmentation. Based on a prostate magnetic resonance image, the invention provides a prostate magnetic resonance image segmentation method based on edge distance adjustment level set evolution for the comprehensive segmentation of the internal and external contours of the prostate. Based on the establishment of a level set evolution equation, the method achieves the segmentation of the external contour based on a prostate magnetic resonance longitudinal relaxation time image, and achieves the segmentation of the internal contour based on a prostate magnetic resonance transverse relaxation time image under an external contour constraint condition, thereby further completing the full effective segmentation of the internal and external contours of the prostate. The method can achieve the comprehensive segmentation of the internal and external contours of the prostate, is very close to the ideal result of manual segmentation of a clinical expert, and has a good reference value for the clinical diagnosis and treatment of prostate diseases.

The invention provides a magnetic sensor based on longitudinal relaxation time signal readout. The magnetic sensor takes a longitudinal relaxation time (T1) as a readout signal. The invention also provides a method for constructing a magnetic sensor based on longitudinal relaxation time signal readout, and the use of the magnetic sensor in the fields of biochemical analysis and immunoassay, food safety, environmental detection and the like.

The invention provides a measuring method and device for the underground thick oil molecule chain length. The method comprises the steps that a three-dimensional nuclear magnetic resonance pulse sequence is emitted into a probe of a nuclear magnetic resonance fluid analyzer filled with a thick oil sample, wherein the three-dimensional nuclear magnetic resonance pulse sequence contains three independent windows used for editing information of the longitudinal relaxation time T<1>, information of the diffusion coefficient D and information of the transverse relaxation time T<2> respectively; echo data is collected; inversion is performed on the echo data by adopting a fast inversion algorithm, and a joint probability distribution function about the longitudinal relaxation time T<1>, the diffusion coefficient D and the transverse relaxation time T<2> is calculated; a probability distribution function of the molecule chain length of all components in the thick oil sample is solved according to a pre-established model of the relation between the longitudinal relaxation time T<1> and the molecule chain length of all the components in the thick oil sample or a pre-established model of the relation between the diffusion coefficient D and the molecule chain length of all the components in the thick oil sample or a pre-established model of the relation between the transverse relaxation time T<2> and the molecule chain length of all the components in the thick oil sample.