一体化PET-MR中PET设备性能指标测试研究

摘要

目的:探讨一体化正电子发射断层扫描-MR(PET-MR)在MR常规序列采集时的磁场环境中PET的性能测试.方法:依据国家标准GBT18988-1(NEMA NU2-2007),在MR常规序列采集时,同步测试PET的空间分辨率、散射分数、计数丢失、随机符合、灵敏度、校正精度及图像质量指标.结果:视野中心1 cm处横向和轴向空间分辨率分别为3.9 mm和4.2 mm,10 cm处分别为4.9 mm和6.5 mm.视野中心和距中心10 cm处的系统灵敏度分别为13.5 kcps/MBq和13.8 kcps/MBq,散射分数为36.4%.当放射性浓度为21.6 kBq/ml时最大噪声等效计数率为187.9 kcps;真符合计数率峰值为713.6 kcps,计数丢失及随机符合校正最大误差为13%,散射和衰减校正的相对误差为22.82%.结论:一体化PET-MR在MR常规序列采集时的磁场环境中,PET的性能指标与同期的PET-CT中PET的性能指标相当,甚至更佳.%Objective: To discuss the performance test of PET when integrated PET-MR was in the environment of magnetic field as MR collecting routine sequence. Methods: According to GBT18988-1(NEMA NU2-2007), the space resolution, scattering score, count losing, random coincidence, sensitivity, corrective precision and image quality of PET were synchronously test during routine sequence of MR was collected. Results: The horizontal space resolution and axial space resolution at the 1cm from center of view field were 3.9 mm and 4.2 mm, and they were 4.9 mm and 6.5 mm at 10 cm, respectively. And the system sensitivities at center of view field and 10cm from center of view field respectively were 13.5 kcps/MBq and 13.8 kcps/MBq, and the scatting score was 36.4%, and the equivalent counting rate of the largest noise were 187.9 kcps when radiation concentration was 21.6 kBq/mL. Besides, the peak value of real coincidence counting rate was 713.6 kcps, and count losing and the largest error of random coincidence correction was 13%, and the relative error of scattering correction and damping correction was 22.82%. Conclusion:During integrated PET-MR in the environment of magnetic field when the routine sequence of MR was collected, the performance indicator of PET was equal with performance indicator of PET in PET-CT, or even better.