Comparison of effects of absolute scatter correction and relative scatter correction on image quality in PET reconstruction
10.3760/cma.j.cn321828-20220322-00085
- VernacularTitle: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
- Author:
Changzhi DU
1
;
Xiangxi MENG
;
Qing XIE
;
Yan ZHANG
;
Shiwei LIU
;
Feng WANG
;
Hua ZHU
;
Jiangyuan YU
;
Zhi YANG
;
Nan LI
Author Information
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
- Keywords:
Algorithms;
Image processing, computer-assisted;
Scattering, radiation;
Artifacts;
Positron-emission tomography;
Tomography, X-ray computed;
Phantoms, imagi
- From:
Chinese Journal of Nuclear Medicine and Molecular Imaging
2023;43(8):486-491
- CountryChina
- Language:Chinese
-
Abstract:
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 18F. 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 18F (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 ( 18F-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 and χ2 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 18F-FDG PET/CT patients, the CVliver of the relative correction (9.67%(8.00%, 11.00%)) was significantly lower than that of absolute correction (11.00%(9.00%, 12.00%); z=-2.57, P=0.010), indicating the higher image quality of images with relative correction. In abnormal images, the image quality of absolute correction was significantly higher than that of relative correction with fewer and less severe artifacts (dislocation cases: 9/10 vs 4/10; χ2=5.50, P=0.019; surface contamination cases: 9/10 vs 4/10; χ2=5.50, P=0.019). Conclusions:The relative scattering correction is suitable for normal situations in clinical PET acquisition. However, with dislocation or surface contamination, the absolute scattering correction helps to reduce the artifacts and improve the image quality.
