MR信噪比一幅图像测量方法与两幅图像测量方法对照研究

目的对比分析MR信噪比一幅图像测量方法和两幅图像测量方法的差异与关系.方法利用Magphan体模的均匀模块在8台不同场强、不同厂家的MRI设备上进行实验.利用一幅图像测量方法和两幅图像测量方法得到信噪比结果.计算不同测量方法的重复性(Rp1和Rp2)及两幅图像测量方法的信噪比与一幅图像测量方法的信噪比的比值(R).结果8台设备的检测结果为:Rp1在77.65%～98.78%之间;Rp2均大于99.00%;R值在0.39到9.50之间.结论利用两幅图像测量方法得到信噪比的重复性较好,在MR系统稳定性较好的条件下,能够真实反映MR系统信噪比.但是在进行MR系统性能检测过程中,应结合两幅图像测量方法和一幅图像测量方法对信噪比进行评价,利用Rp1、Rp2和R给出信噪比检测结论,与其他性能参数相结合可对MR系统其他性能进行评价,如主磁场均匀性、主磁场稳定性、射频场与梯度场的性能,使检测结果能够更准确地反映MRI设备的质量状况.

A Study of Comparison of Single-image Test Method and Two-image Test Method Regarding MR Signal-to-noise Ratio

Objective To evaluate and compare two signal-to-noise ratio ( SNR ) test methods for MR. They are single-image test method and two-image test method.Method The uniform module of Magphan phantom was used for eight MR imaging devices of different magnetic field strength. They were made by different manufactures. SNR were measured with two-image test method and single-image test method. Repeatabilities of single-image test method ( R p1 ) and two-image test method ( R p2 ) were calculated. SNR of two-image method and single-image method were compared, and the ratio ( R) were obtained.Result The R p1 of 8 MR imaging devices were between 77^65% and 98^78%; however the R p2 were all greater than 99^00%; the values of R were all between 0^39 and 9^50.Conclusion The repeatability of two-image test method was better. If the MR system is stable, the SNR of two-image test method can show the true SNR of MR. However, in order to evaluate the SNR objectively and exactly, the results of two-image test method and single-image test method should be combined. The R p1 ,R p2 and R were all used to evaluate the SNR. If they are combined with other parameters, such as performance of RF subsystem, gradient subsystem, homogeneity and stability of magnetic field, the performance of MR can be evaluated even better.