PET显像部分容积效应的实验研究

目的部分容积效应是影响PET图像质量及定量分析精度的主要因素,本文目的是探讨PET FDG图像中热灶的部分容积效应及影响因素.方法采用西门子ECAT EXACT HR 型PET.实验模型为圆柱体内分布着13个内径为3～29 mm的柱状热灶.热灶(18F-FDG)的放射性浓度363.94～8.55 kBq/ml分17次扫描.采用OSEM和FBP两种重建方法.由图像热灶的恢复系数及半高宽分析部分容积效应.结果恢复系数随热灶尺寸的减小而减小;恢复系数和热灶的半高宽不随其实际放射性浓度而变化;不同的重建条件影响恢复系数和热灶的半高宽.结论 PET图像的部分容积效应随病灶尺寸的减小而加重;与重建条件有关;但不随病灶放射性浓度变化.

Partial volume effect in PET images: phantom study

Objective The partial volume effect (PVE) is a main factor to impair the image quality and the accuracy of the quantitative analysis of PET. The aims of this study were to investigate PVE on PET images and the factors influencing the PVE. Methods With PET system (Siemens ECAT EXACT HR ), seventeen emission scans were performed with a radioactivity concentration of 363.94-8.55 kBq/ml for a cylindrical phantom in which there were 13 hot cylindrical lesions with inner diameter 3-29 mm. The images were reconstructed using OSEM algorithm and FBP algorithm respectively. The recovery coefficient and the full width at half maximum of the hot lesion were measured. Results The results showed the hot lesions' recovery coefficient decreased with the decreasing lesions' size; the recovery coefficient and the lesion's full width at half maximum were different with the different reconstructed algorithms, and they did not varied with the true radioactivity concentration. Conclusion PVE severity increases with decreasing size of the lesion, and don't vary with the radioactivity concentration of the lesion; the reconstructed algorithms could influence the PVE severity.