Flow compensation method for nuclear magnetic resonance imaging system

Abstract

The invention discloses a flow compensation method for a nuclear magnetic resonance imaging system. The flow compensation method is characterized by comprising the following steps that: (1) gradient combined pulses which satisfy flow compensation are applied in a frequency encoding direction between a 90-degree radio frequency pulse time series and a 180-degree radio frequency pulse time series of a fast spin echo (FSE) sequence; (2) a scattering gradient is applied before a signal acquisition gradient and before 180-degree radio frequency pulses, and a compensation gradient is applied after the acquisition gradient, and the signal acquisition gradient, the scattering gradient and the compensation gradient jointly form a first-order gradient velocity compensation gradient; (3) phase encoding gradient amplitude is set to be zero, and the time series of the sequence is set, and the amplitudes of the gradients are adjusted, and the amplitude of echo signal peaks of an echo chain is made to reach a maximum value, and the debugging of the sequence is completed; and (4) the sequence is outputted to a spectrometer, so that flow compensation can be realized. With the flow compensation method for the nuclear magnetic resonance imaging system of the invention adopted, situations such as cerebrospinal fluid flow and spinal fluid flow artifacts and image blurring can be significantly inhibited, and therefore, the problem of image artifact generation which is caused by physiological movement such as blood flow or periodic movement can be alleviated.

Description

technical field [0001] The invention belongs to the technical field of magnetic resonance imaging, in particular to a flow compensation method for a nuclear magnetic resonance imaging system. Background technique [0002] Magnetic resonance imaging (MRI) has become a very important imaging method in medical diagnosis. Conventional magnetic resonance imaging sequence, by controlling the radio frequency pulse and the gradient amplitude and timing imaging of the three encoding directions of Gx, Gy, and Gz, for static tissues, the cumulative phase of the gradients in the three directions after echo acquisition is zero, but the flow The liquid (blood, breathing, heartbeat, gastrointestinal peristalsis and other physiological movements) has a certain flow velocity, which will cause the phase accumulation of the spin magnetization vector in the gradient direction, which will cause the echo signal amplitude to decrease, and the image pulsation artifacts shadowing is severe and imag...

AI Technical Summary

Problems solved by technology

In the conventional MRI sequence, by controlling the radio frequency pulse and the gradient amplitude and timing imaging of the three encoding directions of Gx, Gy, and Gz, for static tissues, the cumulative phase of the gradients in the three directions after echo acquisition is zero, but the flow The liquid (blood, breathing, heartbeat, gastrointestinal peristalsis and other physiological movements) has a certain flow velocity, which will cause the phase accumulation of the spin magnetization vector in the gradient direction, which will cause the amplitude of the echo signal to decrease, and the image pulsation artifacts Severe shadowing, degraded image quality

Images