对MRI设备层间射频信号干扰进行检测的实践

Initial practice on cross-talk tests for MRI scanners

目的对3台MRI设备的层间射频信号干扰情况进行检测,以加深对层间射频信号干扰现象的认识。方法通过3台MRI设备(设备1:GE 1.5T HDi,装机时间:2012年;设备2:GE 3.0T HD,装机时间:2006年;设备3:GE3.0T750W,装机时间:2016年)采用轴位T1WI序列扫描ACR模体,记录层间距为5.0、1.0、0.5和0mm时的SNR,绘制SNR变化百分比与层间距百分比的函数图。处置标准:当层间距从5mm减小到0时,由层间射频信号干扰作用所导致的SNR的下降不超过20%。结果当层间距由5mm减小到0时,设备1的SNR下降幅度为18.16%,设备2的SNR下降幅度为23.57%,设备3的SNR下降幅度为10.75%;设备1和设备3的层间射频信号干扰检测结果达到处置标准,设备2(使用时间超过10年)的检测结果未达标。结论 3台MRI设备都存在不同程度的层间射频信号干扰现象,其中使用时间最久的设备检测结果不达标。层间射频信号干扰检测应该在临床质量控制工作中受到重视。

Objective To detect the cross-talk RF signal interference of three MRI scanners,in order to deepen the understanding of cross-talk RF signal interference.Methods Three different GE magnetic resonance imaging scanners（GE1.5 T HDi,installation time：2012;GE 3.0 T HD,installation time：2006;GE 3.0 T750 W,installation time：2016）were tested.The axial T1-weighted sequence was used to scan ACR phantom.Slice gaps with 5.0 mm,1.0 mm,0.5 mm and 0 were performed,respectively.SNR values were also recorded.Based on the results,the percentage change charts of SNR with slice gaps were made.Test standard was set as SNR decreased less than 20% when the slice gap reduced from 5 mm to 0.Results When slice gap was reduced from 5 mm to 0,SNRs for three scanners decreased by 18.16%,23.57% and10.75%,respectively.Both the results of cross-talk obtained with GE 1.5 T HDi and GE 3.0 T750 Wscanner met the test standard,while the result obtained with GE 3.0 T HD（used for more than 10 years）was below the standard.Conclusion The cross-talk RF signal interference still exists for three MRI scanners.The test result of the scanner used for the longest time is unqualified.The quality control test of cross-talk should be done in the daily work.