一种用于直接四维PET显像的动态散射校正方法

摘要

Objective To propose a method of dynamic scatter correction for direct 4-dimensional (4D) PET parametric image reconstruction. Methods Scatter correction for direct 4D PET parametric im-age reconstruction was achieved by extending 3-dimensional (3D) static single scatter simulation (SSS) into 4D dynamic SSS with the help of spatiotemporal cubic polynomial interpolation. The 2 h-serotonin transporter tracer 11 C-2-(2-(dimethylaminomethyl)phenylthio)-5-fluoromethylphenylamine (AFM) brain List mode data of 3 volunteers were obtained from a human brain-dedicated high resolution research tomograph (HRRT) PET scanner. Parametric images (K1 and VT ) were reconstructed by both conventional frame-based method (FM) and direct 4D method. Estimated scatter fractions by both methods were compared. Paired t test was used to analyze the data. Results Scatter fractions derived from FM and direct 4D method were 30.1％(6. 35×107 / (2.11× 108 )), 32.0％ (6.82× 107 / (2.13× 108 )) and 34.4％ (7.22× 107 / (2.10× 108 )), 30. 0％(6.33×107 / (2.11×108 )), 33.3％(7.10×107 / (2.13×108 )) and 34.1％(7.16×107 / (2.10×108 )) for the three subjects, respectively (t = -0.002, P>0.05). Scatter fractions obtained by the two methods were comparable. There was no significant difference between K1(FM: (0.51±0.11) ml·min-1 ·cm-3 , 4D: (0.48±0.09) ml·min-1 ·cm-3) and VT (FM: (24.77±11.80) ml/ cm3, 4D: (27.85±12.65) ml/ cm3) in the two methods (t values: -0.01, -0.97, both P>0.05). Conclusion The proposed dynamic scatter cor-rection method can be used for direct 4D parametric imaging and make it feasible for clinical use.%目的 提出一种适用于临床的直接四维(4D)PET参数化显像动态散射校正方法.方法 对传统的空间三维(3D)单散射模拟校正方法进行时域和空域插值拓展,获得时域和空域连续的PET散射事件.通过List mode在人脑专用高分辨率研究型断层显像系统(HRRT)PET仪上采集3名志愿者脑部2 h 11 C-2-[2-(二甲基氨基甲基)苯硫基]-5-氟甲基苯基氨基(AFM)PET数据,将基于帧的方法(FM)获得的参数化图像和直接4D重建方法所获得的参数化图像进行比较,评估新的用于4D动态散射校正方法的可行性.采用配对t检验进行分析.结果 FM获得的PET散射事件百分比分别为30.1％[6.35×107/(2.11×108)]、32.0％[6.82×107/(2.13×108)]和34.4％[7.22×107/(2.10×108)],4D法对应数据分别为30.0％[6.33×107/(2.11×108)]、33.3％[7.10×107/(2.13×108)]和34.1％[7.16×107/(2.10×108)],结果接近(t=-0.002,P>0.05).2种方法计算所得到脑区的动力学参数[摄取速率K1,FM:(0.51±0.11)ml·min-1·cm-3,4D:(0.48±0.09)ml·min-1·cm-3]和分布体积[VT,FM:(24.77±11.80)ml/cm3,4D:(27.85±12.65)ml/cm3]差异没有统计学意义(t值:-0.01和-0.97,均P>0.05).结论 成功建立一种新的适用于直接4D PET参数化显像的动态散射校正方法,可以达到传统3D校正的效果,并能应用于临床.