92 results about "T2 relaxation" patented technology

A magnetic resonance imaging “MRI” method and apparatus for lengthening the usable echo-train duration and reducing the power deposition for imaging is provided. The method explicitly considers the t1 and t2 relaxation times for the tissues of interest, and permits the desired image contrast to be incorporated into the tissue signal evolutions corresponding to the long echo train. The method provides a means to shorten image acquisition times and / or increase spatial resolution for widely-used spin-echo train magnetic resonance techniques, and enables high-field imaging within the safety guidelines established by the Food and Drug Administration for power deposition in human MRI.

A magnetic resonance imaging "MRI" method and apparatus for lengthening the usable echo-train duration and reducing the power deposition for imaging is provided. The method explicitly considers the t1 and t2 relaxation times for the tissues of interest, and permits the desired image contrast to be incorporated into the tissue signal evolutions corresponding to the long echo train. The method provides a means to shorten image acquisition times and / or increase spatial resolution for widely-used spin-echo train magnetic resonance techniques, and enables high-field imaging within the safety guidelines established by the Food and Drug Administration for power deposition in human MRI.

The present invention is directed to a method and system of tissue or background suppression for the acquisition of image data from blood flow or tissue perfusion. Background suppression with minimal effects upon inflowing spins is achieved through a series of spin locking low level RF pulses that cause adiabatic demagnetization of tissue with a relaxation time T1-rho that is intermediate between T1 and T2 relaxation times. In this regard, the effective transverse magnetization of static tissue resulting from the application of a series of low level RF pulses is reduced and, with the spin locking, longitudinal magnetization regrowth is minimized. As such, inflowing spins to an imaging volume may be directly imaged with significant background tissue suppression. The present invention is particularly applicable to time-of-flight MRA and MR perfusion imaging.

The invention discloses a core stress sensitivity measuring method based on nuclear magnetic resonance. Core stress sensitivity is measured on the basis of conventional displacement experiments and nuclear magnetic resonance testing methods. The method includes the steps that core pretreatment is conducted; a core is subjected to pressurized saturation to simulate formation water; the core is placed in a non-magnetic core clamp to be fixed to an NMR coil; confining pressure is set to test the nuclear magnetic resonance T2 relaxation spectrum of the core; stress values are set for repeated testing at intervals; the highest static stress values are sequentially reduced from 20 MPa to 2.5 MPa, each stress value is kept for a certain period of time to test the T2 spectrum, and the current conventional permeability and NMR permeability are obtained through computation; a core conventional stress sensitivity curve is drawn. By means of the method, people can understand the core stress sensitivity change rule from the micro perspective, characteristics such as pore size distribution, porosity changes and NMR permeability in the experiment process are provided, and change rules of microfracture compact matrix limestone pore size distribution, porosity and permeability in stress sensitivity testing can be effectively detected.

Novel pulse sequences are used to probe the properties of porous media, such as are found in subterranean formations and core samples. This use allows diffusion effects to be uncoupled from the overall T2 relaxation time of the sample. Properties such as internal field gradient and distribution of diffusion coefficients may be determined. A series of pulse sequences are applied to the media to be evaluated. The series of pulse sequences include first and second windows. The first windows include pulse sequences have varying characteristics, such as increasing echo spacing, while the second windows preferably utilize similar pulse sequences which have very small echo spacing. Apparent internal field gradient distribution and apparent diffusion coefficient may be determined as a function of T2 relaxation time. These properties are readily visualized in a two-dimensional map with a first axis being the apparent internal field gradient or alternatively the diffusion coefficient of pore fluids, a second axis being the T2 relaxation times, and the vertical amplitudes being proportional to the proton population. Other properties which may be determined from use of this method include porosity, pore size distribution, oil and water saturation, oil viscosity, oil wettability, and permeability. Also, a method for determining and plotting a T1-MAS 2D spectrum is provided where T1 relaxation time and chemical shift are plotted on x,y axes while intensity of proton population is displayed along a third axis.

The invention relates to a preparation method of HPEI (hyperbranched polyethyleneimine)-encapsulated ferroferric oxide magnetic nano particles, comprising the steps of: adding Fe source to ultrapure water, then adding NH3.H2O, stirring in air, adding HPEI, and reacting at 134-140 DEG C for 3h, wherein the mass ratio of Fe source to HPEI is 1-5 :1; cooling, and carrying out washing and magnetic separation on precipitate to obtain HPEI-encapsulated ferroferric oxide nano particles Fe3O4 / HPEI; and then carrying out different surface modification on the Fe3O4 / HPEI nano particles, such as polyethylene glycolation (PEGlation), acetylation and carboxylation, so as to increase biocompatibility of the nano particles to be used for MRI (magnetic resonance imaging) diagnosis. The process is simple, the reaction conditions are mild and operation and separation are easy; and the prepared iron oxide magnetic nano particles have excellent biocompatibility and T2 relaxation effect, and have potential application value in the field of MRI imaging diagnosis.

The present invention relates to a method capable of utilizing T2 relaxation spectrum to interpret heavy oil reservoir. It is characterized by that said invention utilizes the difference of distributed zones of heavy oil, movable water and irreducible water on the T2 relaxation spectrum to separate them so as to attain the goal of effectively and accurately judging that the heavy oil reservoir is eater-flooded or not. The invented method includes the following steps: sampling, nuclear magnetic resonance analysis and T2 relaxation spectrum analysis and interpretation.

A magnetic resonance imaging (MRI) method for the quantification of the longitudinal (T1) and / or transverse (T2) relaxation times in a sample is provided. According to this MRI method a sample is subjected to an unbalanced steady state free precession (SSFP) sequence comprising a series of consecutive radiofrequency (RF) pulses. By means of this unbalanced SSFP sequence, the first order SSFP FID signal (F1), the lowest order SSFP FID signal (F0), and the lowest order SSFP Echo signal (F−1) are acquired. Based on the F0-signal, the F1-signal and the F−1-signal the longitudinal (T1) and / or transverse (T2) relaxation times of the sample are determined.

The invention discloses a method for measuring the oil content and the water content in drilling fluid through low-field nuclear magnetic resonance. Manganese chloride is used so that the relaxation time of water can be shortened, however, the relaxation time of oil is not affected, hence, the oil and the water in the drilling fluid can be distinguished, and quantitative testing of the oil content and the water content in the drilling fluid is achieved. The method includes the steps that nuclear magnetic resonance analysis is conducted on an original sample of the drilling fluid first, and the T2 relaxation spectrum of the original sample of the drilling fluid is tested; then a manganese chloride solution is added into the original sample of the drilling fluid to be fully stirred; afterwards, nuclear magnetic resonance analysis of the manganese-saturated drilling fluid is performed; the peak area of crude oil is the peak area of the manganese-saturated drilling fluid after the relaxation time is 1 ms, the peak area of the water in the drilling fluid is the difference between the peak area before manganese saturation and the peak area of the crude oil, and the peak area of the crude oil and the peak area of the water in the drilling fluid are introduced into corresponding working curve equations so that the oil content and the water content in the drilling fluid can be obtained; at last, the oil content and the water content of the drilling fluid can be obtained by combining the mass of the drilling fluid.

A system provides B1- and B0-insensitive, blood flow and motion-robust T2-preparation and T2-preparation combined with inversion recovery. An MR imaging system discriminates between imaged tissue types based on transverse relaxation time (T2) or transverse relaxation time combined with longitudinal recovery time (T1). A signal generator generates a pulse sequence for T2 preparation or combined T2-preparation with inversion recovery comprising one or more B1 independent refocusing (BIREF-1) pulses for refocusing of magnetization of an anatomical region of interest being imaged, and different combinations of adiabatic or non-adiabatic tip-down and flip-back pulses. Multiple RF coils transmit RF pulses in response to the pulse sequence and acquire RF data in response to transmission of the RF pulses. A processing system processes the RF data to provide a display image indicating different tissue types with enhanced discrimination based on T2 relaxation time difference or combined T2 and T1 time difference.

The invention relates to a tumor-targeted T1-T2 double nuclear magnetic resonance imaging contrast agent and a preparation method and an application thereof. The contrast agent comprises hyaluronic acid-coated ferroferric oxide composite magnetic nanoparticles, wherein the molecular formula of hyaluronic acid is as shown in the specification; n is an integer of 17-290. The preparation method of the contrast agent comprises the following steps: (1) dissolving hyaluronic acid into deionized water, introducing a gas, and heating to obtain a reaction system A; (2) dissolving ferric salt and ferrous salt into a strong acid to obtain a solution B; (3) injecting the solution B into the reaction system A, adjusting the pH to be alkaline, and then refluxing at a high temperature to obtain a reaction system C; and (4) cooling a reaction system C to a room temperature, and dialyzing to obtain the contrast agent. The invention further provides an application of the contrast agent in T1 and T2 weighted imaging in in-vivo and in-vitro nuclear magnetic resonance. The contrast agent provided by the invention has superparamagnetism and outstanding T1 and T2 relaxation enhancement effects, and is suitable for being used as a T1-T2 double nuclear magnetic resonance imaging contrast agent.

The invention relates to a preparation method of Fe3O4 / Au composite nanoparticles, which comprises the following steps: carrying out PEG modification on PEI; coating the PEI subjected to PEG modification so as to synthesize gold nanoparticles; synthesizing PEI-coated Fe3O4 / Au composite nanoparticles by using a hydrothermal method; and carrying out surface acetylation modification on the PEI-coated Fe3O4 / Au composite nanoparticles. According to the invention, the reaction conditions are mild, and the synthetic steps are simple; and prepared Fe3O4 / Au composite nanoparticles are good in colloidal stability, biocompatibility, T2 relaxation effect and X-ray attenuation properties, and have a potential application value in the field of MR / CT bi-modal imaging diagnosis.

The present invention relates to a rapid evaluation method for rock core wettability change caused by a nanometer fluid, wherein the T2 relaxation times of water before and after treatment of rock core with a nanometer fluid are tested by using special rock core nuclear magnetic resonance equipment, and the T2 cutoff value and the change thereof are determined so as to rapidly determine the rock core wettability change. The concrete method comprises: saturating rock core with water, and testing a T2 relaxation spectrum; removing movable water from the rock core through a centrifugal method and a gas flooding method, testing the T2 relaxation spectrum of pore wall bound water, and respectively accumulating the two T2 relaxation times to obtain the T2 spectrum accumulation curve of the saturated water and the T2 spectrum accumulation curve of the bound water; making a straight line parallel to the horizontal axis by using the maximum value of the T2 spectrum accumulation curve of the bound water, and making the straight line and the T2 spectrum accumulation curve of the saturated water intersect to obtain a T2 cutoff value; and determining the rock core wettability change through the change of the T2 cutoff value. According to the present invention, the process is simple, the evaluation is rapid, the injection of crude oil during the detection process is not required, and the secondary use of the rock core is not affected.

The invention relates to a one-dimensional ferroferric oxide magnetic nano chain and a preparation method thereof in the technical field of nanometer. The preparation method comprises the following steps: putting ferroferric oxide nano druses into a mixed solution of absolute ethyl alcohol and tetrahydrofuran for ultrasonic dispersion; respectively adding HCCP and BPS in the solution for further ultrasonic dispersion, and finally adding triethylamine; and preparing the one-dimensional ferroferric oxide magnetic nano chain packed by loop crosslinking type polyphosphazenes after the reaction at room temperature. The one-dimensional magnetic nano material has excellent dispersion stability in water and polar solvents such as ethanol, acetone, tetrahydrofuran and the like, and is convenient for the following-up surface modification and application; simultaneously, compared with the zero dimension ferroferric oxide nano druses, the one-dimensional ferroferric oxide magnetic nano material has high T2 relaxation rate, and excellent biological application value of magnetic separation and magnetic resonance imaging (MRI) and the like.

A magnetic resonance imaging “MRI” method and apparatus for lengthening the usable echo-train duration and reducing the power deposition for imaging is provided. The method explicitly considers the t1 and t2 relaxation times for the tissues of interest, and permits the desired image contrast to be incorporated into the tissue signal evolutions corresponding to the long echo train. The method provides a means to shorten image acquisition times and / or increase spatial resolution for widely-used spin-echo train magnetic resonance techniques, and enables high-field imaging within the safety guidelines established by the Food and Drug Administration for power deposition in human MRI.

The invention provides a method for nondestructive detection of water and fat contents of yellow croaker. The method comprises 1, yellow croaker sample detection: acquiring a transverse relaxation signal through a CPMG sequence so that a yellow croaker sample transverse relaxation spectrum is obtained, 2, determination of yellow croaker water and fat contents, 3, building of yellow croaker water and fat content prediction models: building prediction models through the T2 relaxation spectrum as an independent variable and water and fast contents as dependent variables, and 4, signal data analysis and processing. The method researches correlation of the spectrum and ingredients, utilizes yellow croaker low field nuclear magnetic resonance relaxation data as a research object and yellow croaker water and fast contents as indexes to build the yellow croaker water and fat content PCR and PLSR prediction models and realizes fast detection of water and fat contents of the yellow croaker.

A method for calculating a sensitivity distribution of a receive coil and taking a tomographic image of a subject, based on magnetic resonance signals received by a surface coil in an imaging sequence with a plurality of different echo times TE1 and TE2 in a reference scan, a plurality of reference images are produced by a first reference image producing section; and based on the plurality of reference images, a T2 relaxation time is calculated by a T2 relaxation time calculating section. Then, based on the calculated T2 relaxation time, a T2-weighted image at the echo time TE2 is calculated by a T2-weighted image calculating section, and thereafter, based on the reference image and T2-weighted image at the echo time TE2, a sensitivity distribution is calculated by a sensitivity distribution calculating section. Based on the sensitivity distribution, a tomographic image by an actual scan is corrected by a correcting section.

The invention discloses a testing method of the specific surface area of a particulate matter in a suspension system. The testing method comprises the following steps: (1) carrying out nuclear magnetic resonance detection on a solvent, controlling the temperature of the solvent by virtue of a metal bath, carrying out CPMG impulse sequence testing on the solvent to obtain T2 relaxation time of the solvent, and calculating relaxation rate R2f of the solvent; (2) adding a particulate matter sample into the solvent, so as to obtain suspension liquid containing the particulate matter sample; (3) carrying out the nuclear magnetic resonance detection on the suspension liquid containing the particulate matter sample, controlling the temperature of the suspension liquid by virtue of the metal bath, carrying out the CPMG impulse sequence testing on the suspension liquid to obtain T2 relaxation time of the particulate matter sample, and calculating the average relaxation rate according to a formula: R2=PbR2b+PfR2f; and (4) calculating the specific surface area of the particulate matter according to the following formula: Sa=(R2sp*R2f) / (Psi*Kp). According to the testing method, the specific surface area of the particulate matter in a suspension state can be tested.

The invention discloses a carbon nanotube / chitosan / magnetic ferrite nanoparticle composite material. A preparation method of the material comprises the following steps of: coating chitosan polymer and magnetic ferrite nanoparticles on multi-wall carbon nanotubes from inside to outside in turn; modifying the surfaces of the carbon nanotubes by coating the chitosan; and depositing the magnetic ferrite nanoparticles on the carbon nanotubes in situ by a hydrothermal method. The material prepared by the method has higher saturation magnetization rate and T2 relaxation coefficient, and is a good magnetic resonance imaging contrast medium. In the invention, concentrated acid oxidation treatment is not required to be performed on the carbon nanotubes in advance, so that the structural integrity of the carbon nanotubes is protected; and the preparation method has the advantages of readily available raw materials, low cost and the like, is easy to operate and is suitable for industrial production.

An MRI method includes performing a first image acquisition module of a pulse sequence to acquire a first MR data from slices disposed at different locations in a region of interest (ROI) of an object; performing a second image acquisition module of the pulse sequence, to acquire a second MR data from the slices disposed at the different locations of the ROI, with a T2 preparation time different than that of the first image acquisition module; and generating a T2 map based on the acquired first MR data and the acquired second MR data.

The invention provides a preparation method of a targeted superparamagnetic nano-probe. The method includes the steps of: 1. preparing ferroferric oxide nano-particles with a particle size of 10-20nm in an oil phase by high temperature thermal decomposition; 2. synthesizing an amphiphilic polymer; 3. conducting aqueous phase transformation of the ferroferric oxide nano-particles obtained by step 1 through the amphiphilic polymer obtained by step 2 so as to obtain water-soluble superparamagnetic nano-particles; and 4. under the coupling effect of EDC / NHS, subjecting the water-soluble superparamagnetic nano-particles obtained by step 3 to covalent coupling with a target molecule, thus obtaining the targeted superparamagnetic nano-probe. The invention also provides an application method of the probe. Under the action of a separation column and an applied magnetic field, the probe can specifically and effectively capture and separate target cells. Compared with the prior art, the probe prepared by the method provided by the invention has the advantages of uniform particle size, high T2 relaxation rate, good stability, high pH value, high salt tolerance, and good target cell separation effect.

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.

In a method and an apparatus for automatic determination of objects that attenuate high energy / penetrating radiation by magnetic resonance, the magnetic resonance apparatus scans and prepares MR images, and the MR images contain information about the T2 relaxation time constant. Subsequently, penetrating radiation-attenuating objects are determined in the MR images by means of the T2 relaxation time constant.

The invention discloses an evaluation method of the mobile oil ratio and the mobile oil source quantity of a low porosity and low permeability sandstone reservoir. The evaluation method comprises thefollowing steps of (A) acquiring oil-gas geology data of a target layer of an evaluation region; (B) performing sampling at different depths of the target layer of the evaluation region to obtain twoor more rock core samples, and determining the porosity and the permeability of each rock core sample; (C) adopting a low porosity and low permeability sandstone reservoir mobile oil ratio evaluationmethod to determine the mobile oil ratio of each rock core sample; (D) according to the porosity, the permeability and the mobile oil ratio of each rock core sample, establishing a relationship formula of the porosity, the permeability and the mobile oil ratio, and calculating the reservoir mobile oil ratio; and (E) calculating the mobile oil source quantity of the target layer of the evaluation region according to the reservoir mobile oil ratio. The mobile oil ratio calculation method provided by the invention does not need to consider a T2 relaxation time cutoff value and is higher in reliability by calculating the mobile oil ratio according to nuclear magnetic resonance T2 spectrum changes of the rock core samples before displacement and after displacement.

The invention relates to a nano magnetic resonance imaging contrast agent and a preparation method thereof. The contrast agent consists of external aqueous phase and humic acid substance-modified super-paramagnetic ferrite nano crystal dispersed in the external aqueous phase. The super-paramagnetic ferrite nano crystal is synthesized by adopting a chemical co-precipitation method, and the grain diameter is 15 to 30 nanometers. The nano crystal is purified and then dispersed in the external aqueous phase to form the contrast agent for intravenous injection. The contrast agent can be stabilized for over two years. The contrast agent has low toxicity, good biocompatibility, large time window and high saturation magnetization, and the half-life period of the contrast agent in the blood reaches 30 to 60 minutes. The contrast agent is absorbed by netlike endothelial systems in liver and spleen tissues through intravenous injection, and is focused in the liver and spleen tissues so as to shorten the T2 relaxation time. In a T2 image, signals of normal liver and spleen tissues are obviously reduced, and signals of tumor or pathological change tissues have no obvious change, so the contrast agent improves the imaging contrast of the focus and the normal tissue and can be used for early diagnosis of pathological changes such as micro tumor of liver and spleen tissues and the like.

A method of generating 2D or 3D maps of MRI T1 and T2 relaxation times by acquiring 2D or 3D MRI gradient-echo images and extracting the T1 and T2 values from the images, wherein MRI images are acquired using a combination of gradient-echo sequences, including a first MRI image acquired using a SSFP-FID (Steady State Free Precession-Free Induction Decay) acquisition sequence; two further images acquired using a Dual-Echo SSFP acquisition sequence; and the T1 and T2 values are extracted for each image pixel or voxel from the corresponding MRI signals.

The invention relates to a core oil / water calibration method based on a nuclear magnetic resonance transverse relaxation spectrum line (see Fig. 1 for the block diagram of the operation procedure). According to the method, in the process of saturating a core with oil / water before a core flooding experiment, the corresponding relationship between the oil / water mass or volume in the core and the peak area of a nuclear magnetic resonance T2 relaxation signal is tested, that is, a more accurate calibration result of the oil / water mass or volume and the signal amplitude is obtained without affecting the experimental operation procedure, so that the calibration is achieved. By using the calibration result, the change of the oil / water mass or volume in the core can be directly obtained by testingthe T2 relaxation spectrum line in the core flooding process, and the mass / volume and the recovery ratio of the produced oil / water can be further determined. According to the scheme of the invention,the key information of a nuclear magnetic resonance core flooding experiment is calibrated in real time based on the nuclear magnetic resonance T2 relaxation spectrum and the actual core flooding experiment, so that the accuracy and reliability of the experimental data can be improved, and the interference to the subsequent core flooding experiment cannot occur.

The present disclosure provides a method of DDCE-MRF. The method can include: a) introducing two or more contrast agents to a region of interest (ROI) of a subject, the two or more contrast agents having different relaxivities; b) measuring a T1 relaxation time and a T2 relaxation time for locations within the ROI using magnetic resonance fingerprinting (MRF); c) determining, using equations that relate the different relaxivities, the T1 relaxation time, the T2 relaxation time, and concentrations of the two or more contrast agents, the concentrations of the two or more contrast agents for each of the locations within the ROI; and d) producing an image depicting the ROI based, at least in part, on the concentrations of the two or more contrast agents.

The invention provides a method for nondestructively testing trepang autolysis on basis of a nuclear magnetic resonance technique. The method comprises the following steps: carrying out nuclear magnetic resonance signal collection on the trepang under the same parameters by adopting a magnetic resonance imaging analyzer and utilizing a CMPG sequence, thereby acquiring a transverse relaxation spectrum; and then judging the change of the content of free water in the trepang according to the degree of left shifting of T2 relaxation peak. According to the method for analyzing the water content change in the trepang autolysis process through low-field nuclear magnetic resonance provided by the invention, the transverse relaxation time spectrum T2 and the magnetic resonance imaging of the fresh bowel-cut trepang are taken as main analyzing basis, so as to quickly judge the water content change in the trepang autolysis process. The method provided by the invention has the advantages that the accuracy of the measuring result is high, the consumed time is short, the sample is free from being damaged, the inner visible information of the sample can be supplied, and the like. The reliable information is supplied to the detection for the autolysis process of the bowel-cut trepang and the change in the quality during the autolysis process of the bowel-cut trepang.