数据采集方式对脑PET图像的影响

The study on acquisition mode and reconstruction parameters of brain FDG PET images

目的 评价不同采集方式对1 8F 脱氧葡萄糖 (FDG)PET脑显像图的影响。方法 通过改变条件和参数 ,分别得到不同采集模式、不同发射计数、不同透射时间下模型脑PET重建图像 ,并与参考图像相比 ,研究不同采集模式、不同数据采集对脑PET重建图像的影响。结果 与二维采集相比 ,三维采集条件下重建图像的本底和高频噪音较多 ,且对颅顶、颅底结构的显示较差 ,但对大脑中间结构的显示与二维采集基本一致。二维采集条件下灰质 白质放射性比值为 2 10 8± 0 183,而三维采集条件下为 2 2 86± 0 2 32 ,差异无显著性 (t=0 .73,P >0 0 5 )。不同发射计数情况下 ,1× 10 8、2×10 8、4× 10 8发射计数下灰质 白质放射性比值分别为 2 10 8± 0 183、2 12 5± 0 15 8、2 16 1± 0 176 ,差异无显著性 (P >0 0 5 )。不同透射计数的情况下 ,随着计数 (即扫描时间 )的增加 ,分割图像中脑模型的轮廓和脑内结构的边界趋向完整和清楚。结论 不同采集模式、不同透射计数和不同发射计数对PET图像会产生一定影响 ,临床应加以注意。

Objective To evaluate the effect of acquisition mode on the brain PET images. Methods After changing conditions and parameters,we got brain PET images of different acquisition modes,different emission counts,different transmission times; and compared with the reference images the impacts of different acquisition modes,different acquisition conditions were assessed. Results Compared with 2D mode, much higher background and noise were observed on the reconstruction images of 3D mode, and the bottoms of the brain structure were not well displayed. But the middle part of brain structure displayed well in 2D and 3D mode without difference; the gray/white radioactivity ratios were 2.108±0.183 and 2.286±0.232 under 2D and 3D mode,respectively. The gray/white radioactivity ratios with different emission counts were 2.108±0.183, 2.125±0.158, 2.161±0.176, respectively, there was no evident difference among them. With transmission counts increasing, the segmented image outline of Hoffman phantom and brain structure became clear and integral. Conclusions Different acquisition modes, different emission counts and different transmission times are of certain impacts on brain FDG PET images, and it should be paid more attention in clinical practice.