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A Measuring Method of Gradient Field in Magnetic Resonance System Based on Diffusion Effect

A measurement method and diffusion effect technology, applied in magnetic resonance measurement, magnetic field size/direction, etc., can solve the problems of time-consuming and inaccurate measurement, achieve short measurement time, improve installation and service efficiency, and facilitate measurement

Active Publication Date: 2021-07-23
MARVEL STONE HEALTHCARE CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Existing technology measurements are very time consuming, taking more than several hours, and are extremely inaccurate

Method used

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  • A Measuring Method of Gradient Field in Magnetic Resonance System Based on Diffusion Effect
  • A Measuring Method of Gradient Field in Magnetic Resonance System Based on Diffusion Effect
  • A Measuring Method of Gradient Field in Magnetic Resonance System Based on Diffusion Effect

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Effect test

Embodiment 1

[0095] Figure 4 Shown is a schematic diagram of an apparent diffusion coefficient measurement sequence for a non-uniform field NMR system. The sequence consists of a series of precisely controlled radio frequency pulses, which are respectively the first excitation pulse, the first refocusing pulse, the second refocusing pulse, and up to the nth refocusing pulse. The constant gradient field is the natural gradient field of the magnet and does not need to be controlled.

[0096] The flip angle of the first excitation pulse is θ, and the flip angle of all subsequent refocusing pulses is 2θ; the phase difference between the first excitation pulse and the first refocusing pulse is 90 degrees, and the phase difference between the first refocusing pulse and subsequent refocusing pulses The phase difference between them is 0 degree; the time interval between the first excitation pulse and the first refocusing pulse is T, which is called the diffusion-sensitive gradient duration; the...

Embodiment 2

[0112] Figure 5 Shown is a schematic diagram of the apparent diffusion coefficient measurement sequence of the non-uniform field NMR system, that is, a typical θ-2θ-2θ-2θ... RF pulse sequence: the first excitation pulse flip angle is θ, followed by several Refocusing pulse, the flip angle is 2θ; the phase difference between the first excitation pulse and the first refocusing pulse is 90 degrees, the time interval between the first excitation pulse and the first refocusing pulse is τ / 2, the first The time interval between the refocusing pulse and the first sampling window is τ / 2; the time interval between the refocusing pulses is τ, which is called the echo interval. The constant gradient field is the natural gradient field of the magnet and does not need to be controlled. One excitation collects n echo signals. Often multiple excitations and acquisitions are also required to improve the signal-to-noise ratio by averaging the signal. In order to estimate the size of the gra...

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Abstract

The invention discloses a method for measuring the gradient field of a magnetic resonance system based on a diffusion effect, which consists of a non-uniform field magnet, a nuclear magnetic resonance spectrometer, a radio frequency power amplifier, a radio frequency coil, and a standard quantitative water model with known ADC coefficients and T2 relaxation time constants, etc. composition. Multiple sets of signals are acquired through magnetic resonance sequences with different diffusion-sensitive gradient durations or different echo intervals, and the gradient field size is fitted from the multiple sets of signals. This method does not require additional special magnetic field detection equipment, the measurement time is short, and it is easy to integrate into the magnetic resonance system, which makes it very convenient to complete the gradient field measurement at the installation site, and improves the efficiency of installation and service.

Description

technical field [0001] The invention relates to the technical field of nuclear magnetic resonance, in particular to a method for measuring a gradient field of a magnetic resonance system based on a diffusion effect. Background technique [0002] Nuclear magnetic resonance technology is a technique that uses the nuclear magnetic resonance phenomenon of hydrogen protons to image or detect the composition and structure of substances. Nuclei containing a single number of protons in the human body, such as the hydrogen nucleus, have a spin motion for the protons. The spin motion of charged atomic nuclei is physically similar to individual small magnets, and the directionality distribution of these small magnets is random in the absence of external conditions. When the human body is placed in an external magnetic field, these small magnets will rearrange according to the field lines of the external magnetic field. At this time, the atomic nuclei are excited by radio frequency pu...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R33/24
CPCG01R33/24G01R33/56341G01R33/3808G01R33/4625
Inventor 吴子岳罗海陈潇叶洋
Owner MARVEL STONE HEALTHCARE CO LTD
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