A Design Method of Compressed Helical Gradient RF Pulses with Reduced Specific Absorption Rate

Abstract

The invention provides a compressive spiral gradient radio frequency pulse design method reducing the special absorption rate. The method comprises the steps that pre-scanning is carried out on a magnetic resonance instrument to acquire the excitation radio frequency field distribution of a scanning object; the energy distribution of the excitation Fourier space, namely k space, is calculated according to the target excitation profile; a traditional spiral gradient trajectory is acquired through the excitation resolution and the excitation view field design; the gradient trajectory is combined with the energy distribution of the k space to design the compression factor of the spiral gradient trajectory, so as to acquire a compression-type spiral gradient trajectory; and according to the excitation target and the radio frequency field distribution in pre-scanning, the parallel excitation pulse design method of the spatial domain is used to calculate the radio frequency pulse waveform and size of each excitation channel under the compression-type spiral gradient trajectory. Compared with the existing spiral gradient trajectory, the method proposed by the invention has the advantages that the peak radio frequency intensity of each emission channel can be reduced under the similar excitation effect; and radio frequency energy absorbed by the scanning object is reduced, namely the specific absorption rate (SAR).

Description

technical field [0001] The invention belongs to the technical field of information processing, and relates to a compression-type spiral gradient radio frequency pulse design method for reducing special absorption rate. Background technique [0002] Magnetic resonance imaging (MRI) is a non-invasive imaging technique without ionizing radiation. Its good contrast in soft tissue imaging makes MRI widely used in the field of clinical medicine. In order to meet the detection needs of small lesions in the clinic, magnetic resonance imaging technology is developing towards high resolution and high signal-to-noise ratio, which usually makes the scanning time longer and makes the scanning results more sensitive to motion and magnetic field inhomogeneity, which leads to blurred images , or signal loss, which in turn causes diagnostic errors, limiting clinical applications. [0003] Regional imaging technology (rFOV) is a technology that reduces scan time, motion artifacts, and suscep...

AI Technical Summary

Problems solved by technology

In terms of RF pulse design, this method is relatively simple to implement, but it does not consider the distribution characteristics of k-space energy. For example: considering the usual square excitation shape, the k-space energy is mainly concentrated on the center of k-space and the kx and ky coordinate axes.

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