不同处理方式对FDG PET图像质量的影响

目的：研究不同重建方式对全身18F－脱氧葡萄糖（FDG）PET图像质量的影响。方法：5例正常对照者和5例恶性肿瘤患者全身18F－FDG PET显像（皆同时进行发射和穿透扫描），所有受检者的原始资料分别采用多种重建方式（无衰减滤波法重建，衰减滤波法重建，衰减迭代法重建），同时分析不同衰减平滑方法（Nonquantitative 和Gaussian)对图像质量的影响。结果：无衰减校正影像存在身体中间组织衰减明显，组织结构显示不清，病变容易变形，伪影多，图像质量差，病灶定位较困难，不能定量计算标准取值（SUV）等缺点，衰减校正滤波法重建图像在显示组织结构，定位病变及定量计算方面较非常衰减法好，但图像质量仍较差，衰减校正迭代法重建图像质量好，组织结构显示清楚，伪影少，病灶无变形，定位及定量都较准确，明显优于衰减和非衰减校正滤波法，衰减平滑方法对滤波法影响大，用Nonquantitative法明显优于Gaussian法，衰减平滑方法对迭代法影响较小，Gaussian法比Nonquantitative法略好。结论：不同重建方式对18F－FDG PET图像质量影响很大，以衰减校正迭代法重建（衰减平滑方法为Gaussian)图像质量最好。

The influence of different processing methods on the quality of 18F-FDG PET wholebody images

Objective The aims of this study was to evaluate the influence of different reconstruction methods on the quality of 18 F-fluorodeoxyglucose (FDG) PET wholebody images and was to select a good reconstruction method. Methods 18 F-FDG wholebody scanning was performed on 5 normal subjects and 5 patients with known malignancy. The raw data of each one were reconstructed with different reconstruction methods,including ordered subsets-expectation maximization (OSEM) reconstruction, attenuation-corrected and noncorrected backprojected filter reconstruction. The influence of different smooth methods, such as Nonquantitative and Gaussian, on the image quality was also evaluated. Results In noncorrected images, the central tissue of the body was displayed unclearly because of radioactivity attenuation. Some other shortcomings such as distortion of lesions,artifacts, dificult position of lesions and incapableness of standard uptake value(SUV) measurement were also seen.The image quality was poor.In corrected images,some shortcomings such as the central tissues displayed,the lesion position and the disadvantages of measurement of SUV were overcomed,but the quality of images was still poor because of a lot of artifacts.With OSEM reconstruction,the image quality was improved very greatly. Artifacts were fewer. The central tissues were displayed clearly,and the position of lesion and measurement of SUV were also easy and precise.When reconstructed with backproject filter,the influence of smooth methods on image quality was great and the nonquantitative method was better than Gaussian. When reconstructed with OSEM, the influence of smooth methods on the image quality was little and Gaussian was better slightly. Conclusions The quality of 18 F-FDG wholebody images was influenced by the reconstruction method greatly. With corrected OSEM reconstruction and Gaussian smooth method, the perfect images could be obtained.