Multi-dimensional nuclear magnetic resonance fringe magnetic field imaging experimental device

Abstract

Relating to nuclear magnetic resonance imaging, the invention provides a multi-dimensional nuclear magnetic resonance fringe magnetic field imaging experimental device. The experimental device is equipped with a host computer, a PMAC controller, a spectrometer, an AC servo motor driver, four DC servo motor drivers, an AC servo motor, four DC servo motors, a fringe magnetic field imaging plane lifting platform, an imaging probe, two sample chamber Y axis motion system power transmission lines, five sample chamber rotation motion system power transmission lines, seven sample chamber up-and-down motion system power transmission lines, four sample chamber X axis motion system power transmission lines, a probe coil, and a sample chamber up-and-down motion system worm. The experimental device can realize arbitrary angle adjustment of the sample chamber, stable mechanical discontinuous rotation and relative motion of the sample chamber and the probe coil. Through combination of positioning algorithm and a precise mechanical structure, the experimental device realizes movement of the sample chamber relative to the coil, and solves the problem that existing multi-dimensional fringe magnetic field imaging probe experimental devices in the world cannot realize large size sample imaging under an ultrastrong gradient field.

Description

technical field [0001] The invention relates to nuclear magnetic resonance imaging, in particular to a multi-dimensional nuclear magnetic resonance edge magnetic field imaging experimental device. Background technique [0002] NMR fringe magnetic field imaging technology originated in the late 1980s. Compared with traditional NMR imaging technology, its remarkable feature is to use superconducting magnet edge super strong gradient field to image samples. The gradient field that can be generated by the gradient coils used in magnetic field equipment can generally only reach about 1.5T / m, which is much smaller than the 50-60T / m of the fringe magnetic field, and because the resolution of MRI is directly related to the gradient field strength, so in In terms of image resolution, fringe magnetic field imaging technology has greatly improved compared with traditional MRI technology. In the field of nuclear magnetic resonance imaging, since the molecules of solid samples cannot mo...

AI Technical Summary

Problems solved by technology

In the current patents or related documents published at home and abroad, US Patent US005424644 describes a mechanism that can be used for multi-dimensional fringe magnetic field imaging. This mechanism realizes the attitude adjustment of the sample in the coil, but when adjusting the sample up and down , the relative movement between the probe and the sample is not realized, but the overall movement. In the fringe magnetic field environment of the superconducting magnet, because the gradient field is extremely strong, the large-scale movement of the probe will often cause a drastic change in the magnetic field where the probe is located. Due to the large change of the magnetic field and the increase of uncertain factors, the imaging resolution and signal-to-noise ratio will also be affected, and it is easy to cause image artifacts

The patent WO20008833A2 and the paper "Multi-dimensional magnetic resonance imaging inastray magnetic field" describe the combination of magic angle rotation technology and fringe magnetic field imaging, directly tilt the sample cavity to the magic angle angle, and rotate the sample pneumatically. This method achieves 3D imaging effect, but the movement of the sample relative to the probe has not been realized. When the sample is large, the coverage area of ​​the RF pulse cannot cover the size of the sample, so only small sample imaging experiments can be done, and the pneumatic method also makes the rotation of the sample chamber stable. The performance cannot be guaranteed, which will affect the accuracy of the experimental results

In addition, the authors of the papers "ContrastSTRAFI–MASimaging", "Two-andThree-Dimensional Multinuclear Stray-Field Imaging of Rotating Samples with Magic-Angle Spinning (STRAFI-MAS) From Bioto Inorganic Materials" also tried to apply the off-the-shelf magic-angle rotating commercial probe directly to the edge magnetic field imaging technology to make three-dimensional However, because the commercial magic-angle rotating probe is mainly used for solid-state magnetic resonance spectroscopy, not specifically developed for fringe magnetic field imaging technology, there are many shortcomings, such as the sample rotation speed cannot be well controlled, and the conventional magic-angle rotating probe rotates Poor stability and severe image distortion caused by spatial position changes during the evolution of gradient encoding; and the current magic-angle rotating multi-dimensional fringe magnetic field imaging probes cannot achieve relative movement between the sample and the coil, so that the imaging The size of the sample is limited, and it is impossible to perform multi-dimensional fringe magnetic field imaging of large-sized samples under a super-strong gradient field, and it is also impossible to adjust the multi-angle attitude of the sample at will.

All in all, the current three-dimensional fringe magnetic field imaging experimental device cannot realize the stable rotation of mechanical discontinuity and the movement of the sample cavity relative to the probe coil when imaging large-scale solid samples under an ultra-strong gradient field.

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