System and method for generating magnetic resonance gradient waveform with adjustable digital pre-emphasis

Abstract

The invention relates to a system and method for generating a magnetic resonance gradient waveform with adjustable digital pre-emphasis. The system is provided with a FPGA (Field Programmable Gate Array) and a three-dimensional digital to analog converter, wherein the FPGA receives message queues, relevant to gradient, sent by a magnetic resonance scanning sequence compiler and processes the message queues to form three-dimensional gradient pulse digital waveform signals; the three-dimensional gradient pulse digital waveform signals can meet linear variation and can effectively compensate thegradient eddy-current effect, and number of slope steps can be randomly set; and the signals are processed through the three-dimensional digital to analog converter for generation of three-dimensional gradient pulse simulating waveform signals. The method comprises the following steps of: receiving the message queues of the magnetic resonance scanning sequence compiler; identifying the gradient event attributes of the message queues to obtain different gradient event attributes to carry out a corresponding processing operation, and obtaining gradient waveform data with adjustable digital pre-emphasis; and generating the gradient waveform according to the gradient waveform data. In the invention, the FPGA is used as a hardware carrier, so that the control of the gradient waveform signals has good instantaneity, and the gradient waveform with arbitrary gradient slope characteristics and gradient pre-emphasis characteristics can be obtained.

Description

technical field [0001] The invention relates to the technical field of nuclear magnetic resonance realization, in particular to a system and method for generating a magnetic resonance gradient waveform with adjustable digital pre-emphasis based on parallel processing technology. Background technique [0002] The gradient waveform generator is an important part of the MRI system. In order to be able to apply magnetic resonance imaging to physical phenomena, while sending radio frequency excitation pulses, a gradient waveform generator is also required to generate slice-selective gradient pulse signals and spatially encoded gradient pulse signals in the horizontal and vertical directions within the slice. After the three-dimensional linear gradient signals are amplified by the gradient amplifier, the three-dimensional gradient coil is driven to generate a three-dimensional gradient field, which is used for spatial positioning of each voxel of the measured body. [0003] Howev...

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Problems solved by technology

[0008] For method 1, although it is a combination of digital control and analog control, it generally belongs to the category of analog control, and its waveform time constant is constant or limited, and it is difficult to correlate pre-emphasis parameters with pulse sequence parameters; for For method 2, although it belongs to the category of digital control, it is necessary to configure the pre-emphasis parameters of the multivariate digital filter in advance and save them in a parameter memory, and obtain the time constant and amplitude of the gradient pre-emphasis waveform by address selection The two parameters, when the scan is in progress, form a gradient waveform output according to the same clock beat, so the setting of the pre-emphasis waveform is not flexible, the randomness of the waveform selection is poor, and the real-time performance of the pre-emphasis control is not high; for method 3 In other words, the data measured by this method are reliable, and the automatic setting of gradient pre-emphasis can be realized, but it takes at least 10 minutes to achieve a good compensation effect, and this adjustment operation is independent of the sequence scan control

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