33 results about "T2 value" patented technology

The embodiment of this specification provides a method and device for acquiring a capillary pressure curve of a reservoir. The method comprises: obtaining nuclear magnetic resonance T2 distribution and capillary pressure curves of multiple core samples of the target reservoir; the capillary pressure curve is a relationship curve of non-wetting phase saturation with capillary pressure; establishing nuclear magnetic resonance T2 distribution conversion capillary pressure The nonlinear conversion relational expression of the curve, said relational expression includes a plurality of unknown coefficients; Substituting the T2 value of the nuclear magnetic resonance T2 distribution of each rock core sample and the measured value of capillary pressure into said conversion relational expression, according to a preset algorithm Find the solutions of the multiple unknown coefficients; wherein, the measured value of the capillary pressure is the capillary pressure value of the capillary pressure curve; the nuclear magnetic resonance T2 distribution of the target reservoir and the solutions of the multiple unknown coefficients are substituted into In the conversion relational formula, the capillary pressure curve of the target reservoir is calculated, thereby improving the prediction accuracy of the capillary pressure curve of the reservoir.

The invention relates to the technical field of optimization of medical imaging sequence parameters, that is, a method for simultaneously obtaining T1 weighted imaging by using a RAREVTR sequence for magnetic resonance double-signal nanoprobes. The steps are as follows: (1) Nano-probes with T1 and T2 double contrast signals are equipped with different concentrations, the concentrations are respectively 0.05mM, 0.1mM, 0.2mM, and 0.4mM. (2) The prepared probe phantom is fixed together, placed on the scanning bed in the middle of the magnet and tuned, and then the RAREVTR and MSME sequences are routinely scanned on the ParaVision6.0.1 imaging system to obtain the T1 and T2 values ​​corresponding to different concentrations of probes. (3) After step (2), set the optimal TE value and TR value for the probe solution according to the equation Y=[A+C*(1‑exp(‑TR / T1))]*exp(‑TE / T2) . When imaging with dual-signal probe T1mapping, the RAREVTR sequence with optimized parameters can eliminate the influence of probe T2 signal. When the dual-signal probe T2mapping is used for imaging, the optimized MSME sequence can eliminate the influence of the probe T1 signal. The RAREVTR sequence with optimized parameters can obtain not only accurate T1 values ​​but also approximate T1WI images.

The invention relates to the technical field of nuclear magnetic resonance imaging, and discloses a measurement method, device, computer equipment and non-uniform field magnetic resonance system of ADC‑T2 two-dimensional atlas, which can be used in extremely non-uniform magnetic fields or extremely short In the echo time NMR system, the ADC coefficient and T2 value are fitted from multiple sets of echo signals by acquiring multiple echo signals collected by CPMG sequences with different echo intervals, so that the ADC‑ The T2 spectrum eliminates the need for complex diffusion weighted sequences, has the advantages of simple algorithm and low system requirements, and can reduce the cost of hardware systems such as spectrometer equipment, RF power amplifiers, and RF coils. At the same time, the measurement method also has the characteristics of stable algorithm, is not easily affected by flowing liquid, and is also suitable for substances with small T1 / T2.

The present invention falls within the field of medical equipment quality inspection. Disclosed is a method for preparing a general-purpose MRI phantom material and a method for preparing a general-purpose MRI phantom. In the method for preparing a general-purpose MRI phantom material of the present invention, a ratio formula is established, wherein according to preset T1 and T2 values of the MRI phantom, the ratio of a desired material corresponding to a given T1 / T2 value can be directly calculated, and the range in which the T1 / T2 value can be adjusted is large. The method for preparing a general-purpose MRI phantom of the present invention comprises: according to preset T1 and T2 values of an MRI phantom and the volume of water, taking a prepared MRI phantom material and adding water thereto and mixing same, heating and dissolving same multiple times by means of microwaves, and placing same in an MRI phantom carrier to remove air bubbles by means of ultrasonic waves. In the method for preparing a general-purpose MRI phantom of the present invention, a phantom material can be directly configured as needed, making the efficiency high; heating is performed multiple times by means of a microwave oven, and therefore, the time consumption is short and less water is evaporated; there is no need to filter residue, and the concentration of a solution does not change; and ultrasonic waves are used to remove air bubbles, making operation simple.

The invention relates to a method for obtaining the delay time of a contrast agent. Automatically identify the contrast agent sample in the image, accurately locate the center point of the sample to calculate the radius of the sample test tube, and automatically select the ROI based on the center point of the test tube according to the radius of the test tube, calculate the average value of the pixel signal in the ROI, and the experimental standard deviation. Finally, nonlinear fitting is performed on the automatically extracted signals to accurately, quickly and efficiently calculate the spin-lattice relaxation time T1 and spin-spin relaxation time T2 values ​​of the contrast agent. The process of identifying multiple samples in the image and selecting the sample ROI is a computer-automated process that does not require manual processes. The positioning accuracy, ROI shape consistency, and result accuracy are much higher than traditional methods; this method is from ROI selection, ROI signal extraction to The entire process of nonlinear fitting is a fully automated process, and its time efficiency is much higher than that of traditional methods.

The invention discloses a nuclear magnetic resonance T2 image imaging method provided by the invention, which includes the following steps: Step 1, setting a pulse sequence, and the pulse sequence adopts a fast spin echo sequence. Step 2: Carry out nuclear magnetic resonance test and collect echo signals in the echo chain; the number of echo signals is required to cover the signal intensities at different time points in the transverse relaxation of the measured substance. Step 3, taking the corresponding signal strengths at different time points as K-space data and performing image reconstruction. Step 4: Obtain the MR signal intensity of each excited voxel in the position space by Fourier transforming the image data in the K space. Step five, calculating the T2 value of each excited voxel. The invention can reduce the scanning time and increase the scanning speed, and is suitable for the inspection of autonomous moving organs.

The invention relates to the technical field of nuclear magnetic resonance imaging, and discloses a method for correcting and measuring the decay time constant of a transverse magnetization vector, a device, a computer device and an inhomogeneous field magnetic resonance system. In the NMR system of the echo time, the ADC-T2 two-dimensional spectrum is first fitted by acquiring multiple echo signals collected by SE-CPMG sequences with different b values, and then the transverse magnetization vector decay time constant T2 Make corrections, so that the problem of small T2 measurement values ​​caused by diffusion can be avoided. In addition, a more accurate ADC-T2 two-dimensional map can be further obtained based on the corrected T2 measurement value, ensuring that the T2 value measurement is not affected by echo time and molecular diffusion, and has low system requirements, which can reduce system costs.

The invention relates to a method for determining T2cutoff value by nuclear magnetic resonance logging (NMRL) T2 spectra, comprising the steps of: 1. classifying NMRL T2 spectra by shape characteristics; 2. fitting and obtaining centrifugal spectrum according to different types of logging T2 spectra; 3. making area integration on the centrifugal spectrum and obtaining area of centrifugal spectrum; 4. calculating areas of logging T2 spectra; 5. accumulating the areas of logging T2 spectra, and as the accumulated area is equal to or closest to the area of centrifugal spectrum, the corresponding T2 value is a T2cutoff value. Thus, the invention determines T2cutoff value of each depth point by directly using NMRL T2 spectra.

The invention belongs to the technical field of magnetic resonance imaging, in particular to a method for rapidly quantifying T1ρ based on magnetic resonance fingerprint imaging. The method of the present invention includes adding a spin-lock preparation pulse before the traditional MRF sequence, and through reasonable modeling, the T1ρ evolution of the signal is fused with the T1, T2 evolution of the signal, so that the signal collected at each time point includes T1, T2 and Components of T1ρ. Design the sequence parameters TSL, FA, TR, and TE with pseudo-random changes, and establish a dictionary of different relaxation time value combinations through the evolution of the magnetization vector in the Bloch equation, and match the actually collected image sequence with the dictionary to quantify T1ρ, T1 and T2 values. Compared with the traditional exponential fitting method, the method for quantifying T1ρ of the present invention can greatly shorten the scanning time, and is expected to have greater application value in T1ρ imaging.

The embodiment of the invention discloses a method and a system for determining a transformation relationship between a tight sandstone aperture and a nuclear magnetic resonance T2 value, and relatesto the technical field of oil and gas reservoir stratum geological evaluation. The method comprises the following steps that: carrying out CT (Computed Tomography) on an obtained tight sandstone sample to obtain a three-dimensional digital core; through the three-dimensional digital core, obtaining aperture radius and volume data, and further obtaining a digital core aperture radius distribution diagram; carrying out saturated salt water nuclear magnetic resonance measurement on the tight sandstone sample to obtain a nuclear magnetic resonance T2 spectrogram; and on the basis of the digital core aperture radius distribution diagram and the nuclear magnetic resonance T2 spectrogram, according to an equal porosity principle, establishing a crossplot of the aperture radius rc and the nuclearmagnetic resonance T2 spectrogram, and carrying out fitting to obtain a relational expression of rc and T2. By use of the embodiment of the invention, the quantitative calculation of the transformation relationship between the tight sandstone aperture radius and the nuclear magnetic resonance T2 value is realized. Compared with the transformation relationship obtained through mercury penetration pore throat distribution and the nuclear magnetic resonance T2 spectrogram in the prior art, the transformation relationship obtained by the method is more reliable, and therefore, the tight sandstonereservoir stratum full-scale aperture structure is further accurately represented.