PET重建中绝对散射校正与相对散射校正对图像质量影响的对比  

Comparison of effects of absolute scatter correction and relative scatter correction on image quality in PET reconstruction

作　　者：杜长治 孟祥溪 谢卿[1] 张岩[1] 刘士玮 王风[1] 朱华[1] 于江媛[1] 杨志[1] 李囡[1] Du Changzhi;Meng Xiangxi;Xie Qing;Zhang Yan;Liu Shiwei;Wang Feng;Zhu Hua;Yu Jiangyuan;Yang Zhi;Li Nan(Key Laboratory of Carcinogenesis and Translational Research(Ministry of Education),Department of Nuclear Medicine,Peking University Cancer Hospital&Institute,Beijing 100142,China)

机构地区：[1]北京大学肿瘤医院暨北京市肿瘤防治研究所核医学科、恶性肿瘤发病机制及转化研究教育部重点实验室,北京100142

出　　处：《中华核医学与分子影像杂志》2023年第8期486-491,共6页Chinese Journal of Nuclear Medicine and Molecular Imaging

基　　金：国家自然科学基金(81871387);北京市自然科学基金(7202027)。

摘　　要：目的研究PET/CT图像重建过程中,散射校正算法的选择对临床条件下图像伪影和定量参数准确性的影响。方法采用符合美国国家电气制造商协会(NEMA)NU2标准的躯干体模(简称NEMA体模),以^(18)F溶液灌注模体。固定本底的活度,并改变阳性球中溶液的活度,获得常规比例(4.08∶1)组与极高比例(200∶1)组。体表污染组在极高比例组的基础上,在模体外部放置不同活度(74、37、3.7和0.37 MBq)的小放射源。回顾性选取2012年7月至2021年12月间于北京大学肿瘤医院行PET/CT检查的病例共30例[男21例、女9例,年龄(44.5±10.2)岁],其中常规显像(^(18)F-FDG)病例10例,特殊显像病例20例(位移病例10例,体表污染病例10例)。PET/CT显像后,分别采用相对散射校正(Relative)与绝对散射校正(Absolute)进行图像重建,以靶本底比(TBR)或伪影分级评价体模图像质量,以CV或伪影分级比较临床图像质量。采用Mann-Whitney U检验和χ^(2)检验分析数据。结果NEMA体模常规比例组与极高比例组Relative方式的图像TBR始终高于Absolute方式,差异具有统计学意义[常规比例组:3.30(1.94,4.53)和2.72(1.56,3.56);z=-2.20,P=0.028;极高比例组:105.47(45.62,162.82)和101.36(43.96,155.57);z=-1.99,P=0.046]。体表污染组随着小放射源活度的增加,PET图像伪影越明显,Absolute方式的图像伪影评分始终优于Relative方式,差异具有统计学意义[1.5(1.0,2.0)和2.5(2.0,3.0)分;z=-2.00,P=0.046]。10例常规显像病例Relative方式与Absolute方式的CVliver差异具有统计学意义[9.67%(8.00%,11.00%)和11.00%(9.00%,12.00%);z=-2.57,P=0.010],表明Relative方式的图像质量高。2组特殊显像病例Absolute方式的图像伪影较轻、较少,图像质量始终高于Relative方式,其合格比差异均有统计学意义(位移病例:9/10和4/10;χ^(2)=5.50,P=0.019;体表污染病例:9/10和4/10;χ^(2)=5.50,P=0.019)。结论以Relative方式进行图像重建适用于临床常规情况,但当采集过程�Objective To study the impact of different scattering correction algorithms in the reconstruction of PET/CT images on image artifacts and the precision of quantitative parameters.Methods The phantom as described in the National Electrical Manufacturers Association(NEMA)NU2 standard was filled with ^(18)F.The background activity was fixed,and the activity of the solution in the spheres was adjusted to obtain several configurations,including the normal ratio group(4.08∶1)and the extreme ratio group(200∶1).The surface contamination group with the same ratio as the extreme ratio group contained a small radioactive source with different doses of ^(18)F(74,37,3.7 and 0.37 MBq)placed at the surface of the phantom.PET/CT images of 30 patients(21 males,9 females,age:(44.5±10.2)years)from Peking University Cancer Hospital&Institute between July 2012 and December 2021 were retrospectively analyzed,including 10 with normal images(^(18)F-FDG)and 20 with abnormal images(10 with dislocation during acquisition,10 with surface contamination).The images were reconstructed with relative and absolute scattering correction.The phantom was evaluated using the target to background ratio(TBR)and the artifact classification.CV as well as the artifact classification were used to compare the clinical image quality.Mann-Whitney U test andχ^(2) test were used to analyze data.Results In the normal ratio group and the extreme ratio group,the TBRs of phantom images reconstructed with relative correction were significantly higher than those with absolute correction(normal ratio group:3.30(1.94,4.53)vs 2.72(1.56,3.56);z=-2.20,P=0.028;extreme ratio group:105.47(45.62,162.82)vs 101.36(43.96,155.57);z=-1.99,P=0.046).In the surface contamination group,with the increase of the activity of the small source,the artifact became more obvious,and the artifact classification score of absolute correction was significantly better than that of relative correction(1.5(1.0,2.0)vs 2.5(2.0,3.0);z=-2.00,P=0.046).In the 10 normal ^(18)F-FDG PET/CT patients,the

关 键 词：算法 图像处理 计算机辅助 散射 辐射 伪迹 正电子发射断层显像术 体层摄影术 X线计算机 体模 显象术 

分 类 号：R816[医药卫生—放射医学]