非均匀磁场下的核磁共振技术仿真分析

Simulation Analysis of NMR Techniques under Inhomogeneous Magnetic Field

目的探讨出非均匀磁场下的核磁共振技术条件。方法首先,分析开放式单边磁体非均匀主磁场的特点;其次,探讨CPMG单个衰减指数的回波与回波串幅度的包络线在非均匀场下的特性;最后,研究非均匀场下射频脉宽与带宽的限制条件。结果得出非均匀磁场下核磁共振技术条件,并通过仿真获得满足非均匀场条件下的CPMG信号。结论通过对CPMG序列下的非匀场核磁共振技术研究,并仿真验证了该技术条件的可行性,为后续单边全开放式磁体系统研究奠定基础。

Objective To explore NMR techniques of Inhomogeneous magnetic field. Methods First- ly, we analyzed the characteristics of the open - sided inhomogeneous magnetic field. Secondly, features of CPMG echo of single exponential decay and CPMG echo train envelope in the inhomogeneous field were investigated. Last- ly, the restrictions with RF pulse width and bandwidth under non - uniform field were studied. Results We ob- tained the technical conditions tor the NMR system under inhomogeneous magnetic field and the corresponding CPMG signals by simulation. Conclusion Through studying the inhomogeneous field NMR techniques under CPMG sequence and simulating those technical conditions, we have laid the foundation for the subsequent ＂fully open unilateral magnet＂ system.