An extremely low-field nuclear magnetic resonance imaging system and its baseline calibration method

Abstract

The present invention provides an extremely low-field nuclear magnetic resonance imaging system and a baseline calibration method thereof. The imaging system includes: a nuclear magnetic resonance coil set arranged in a radio frequency shielding room, a prepolarization coil, a reference channel, a first SQUID readout circuit, Program-controlled arithmetic processor, detection channel and the second SQUID readout circuit, and the SQUID control / data collector and host computer located outside the radio frequency shielding room; the present invention utilizes the output of the reference channel to compensate the magnetic signal detected by the detection channel to This cancels the eddy current magnetic field pulse in the detection channel, thereby reducing the output drift of the detection channel and stabilizing the baseline of its output signal. An extremely low-field nuclear magnetic resonance imaging system and its baseline calibration method provided by the present invention solve the problems in the prior art of improving extremely low-field nuclear magnetic resonance imaging through strong prepolarization magnetic field pulses and increasing the size of the second-order gradiometer The problem that the signal-to-noise ratio causes the baseline drift of the output signal.

Description

technical field [0001] The invention relates to the technical field of extremely low-field nuclear magnetic resonance imaging, in particular to an extremely low-field nuclear magnetic resonance imaging system and a baseline calibration method thereof. Background technique [0002] Magnetic resonance imaging (MRI) is a non-invasive tomographic imaging technology. It uses the phenomenon of nuclear magnetic resonance to obtain the electromagnetic induction signal after the proton is excited from the human body, and reconstructs the structural information of human soft tissue through spatial encoding. It has the characteristics of high image resolution, high contrast when imaging human tissues, especially soft tissues, and will not cause damage to the human body, so it has been widely used in clinical medical diagnosis. [0003] At present, the magnetic field strength of commercial MRI equipment commonly used in clinical medicine is above 1T, which can only be realized by superc...

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Problems solved by technology

[0005] In view of the shortcomings of the prior art described above, the object of the present invention is to provide an extremely low-field nuclear magnetic resonance imaging system and a baseline calibration method thereof, which are used to solve the problems in the prior art by strong prepolarization magnetic field pulses and increasing the second step The problem of baseline drift of the output signal when the size of the metric is used to improve the signal-to-noise ratio of extremely low-field MRI

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