双梯度磁共振成像质量参数的比较

Comparison on MR imaging quality parameters between ZOOM and WHOLE gradient Modes with GE Twinspeed MR scanner

目的探讨双梯度MR成像系统常规成像序列在ZOOM和WHOLE梯度模式下的成像质量。方法采用GE双梯度MR系统,在ZOOM和WHOLE梯度模式下对Magphan-SMR170 MR成像参数测试体模内的5个测试平面分别行SE及FSE序列扫描,比较两种梯度模式下的成像质量参数。应用Matlab 7.0软件测量和计算SNR、信号均匀性、实测层厚、层厚误差、层间距误差、几何畸变率,直接在MR显示器上读取空间分辨率数据。结果与WHOLE梯度模式相比,SE序列成像ZOOM梯度模式下SNR及实测层厚差异有统计学意义(P均<0.05);与WHOLE梯度模式相比,FSE序列成像ZOOM梯度模式下SNR、信号均匀性、实测层厚、层间距误差、几何畸变率差异有统计学意义(P均<0.05)。结论 ZOOM梯度模式下的成像质量优于WHOLE梯度模式。临床应用中,在小FOV情况下,常规SE和FSE序列MR检查时应选择ZOOM梯度模式。

Objective To compare the imaging quality parameters between ZOOM and WHOLE gradient modes in routine imaging sequence with GE Twinspeed MR system.Methods MR scanning was performed to 5 test planes of Magphan-SMR170 phantom under ZOOM and WHOLE gradient modes using SE and FSE sequences.The imaging quality parameters including SNR,image uniformity,actual slice thickness,slice thickness error,interlayer spacing error,the rate of geometry distortion and spatial resolution were measured or calculated.Spatial resolution was read on the screen directly,and the other parameters were obtained with Matlab 7.0 software.Results Between ZOOM and WHOLE gradient mode,statistical difference of SNR and actual slice thickness was found using SE sequence（all P0.05）,while there was statistical difference of SNR,image uniformity,actual slice thickness,interlayer spacing error and the rate of geometry distortion using FSE sequence（all P0.05）.Conclusion The imaging quality of ZOOM gradient mode is better than that of WHOLE gradient mode.ZOOM gradient mode should be selected in clinical application of small FOV routine MR examination with SE and FSE sequences.