不同强度高级迭代重建算法在不同噪声水平下对图像质量的影响:体模研究

目的 采用Catphan 500体模及改造后的套环体模，探讨2种体模噪声水平下高级迭代重建算法（ADMIRE）不同迭代强度对图像质量的影响。方法 在12种不同扫描条件下对标准体模组和套环体模组分别进行扫描，采用滤波反投影法（FBP ADMIRE 0亚组）及不同迭代强度ADMIRE 1~5（ADMIRE 1~5亚组）重建图像。测量图像的噪声、SNR、空间分辨率、密度分辨率，比较不同迭代强度图像间的差异。结果 标准体模组：随迭代强度增高，噪声逐渐减低，SNR逐渐增高，空间分辨率无明显改变，密度分辨率逐渐升高，ADMIRE 4、5亚组密度分辨率高于ADMIRE 0~2亚组（P均<0.05）。套环体模组：随迭代强度增高，噪声逐渐减低，SNR逐渐增高，ADMIRE 4、5亚组空间分辨率低于ADMIRE 0~2亚组，密度分辨率逐渐升高，ADMIRE 3~5亚组密度分辨率高于ADMIRE 0~2亚组（P均<0.05）。结论 标准体模图像噪声水平下，ADMIRE技术可提高密度分辨率而不降低空间分辨率；套环体模图像噪声水平下，ADMIRE技术可提高密度分辨率，但高级别ADMIRE技术会降低空间分辨率；推荐以ADMIRE 3作为优选迭代强度级别。

Effect of advanced modeled iterative reconstruction in different strength levels on image quality under different noise: A phantom study

Objective To evaluate the effect of advanced modeled iterative reconstruction (ADMIRE) with different strength levels on image quality in two sets of noise levels using the Catphan 500 phantom and modified collar phantom. Methods Standard phantom (standard phantom group) and collar phantom (collar phantom group) were scanned under 12 different scanning conditions. All images were reconstructed using filtered back projection (FBP; ADMIRE 0 subgroup) and different strength levels ADMIRE 1-5 (ADMIRE 1-5 subgroups). The noise, SNR, spatial resolution and density resolution of the images were measured and evaluated. Results In standard phantom group, with the increase of iterative strength levels, the noise gradually decreased, the SNR gradually increased, the spatial resolution did not obviously change, and the density resolution gradually increased; the density resolution in ADMIRE 4, 5 subgroups were higher than that in ADMIRE 0-2 subgroups (all P<0.05). In collar phantom group, with the increase of iterative strength levels, the noise gradually decreased, SNR gradually increased, and the spatial resolution in ADMIRE 4, 5 subgroups were lower than in ADMIRE 0-2 subgroups; the density resolution gradually increased, and in ADMIRE 3-5 subgroups was higher than in ADMIRE 0-2 subgroups (all P<0.05). Conclusion On condition of standard phantom noise level, ADMIRE technology improves density resolution while does not reduce spatial resolution. On condition of collar phantom noise level, ADMIRE technology improves density resolution, but high strength levels ADMIRE technology will reduce spatial resolution. ADMIRE 3 is recommended as the optimal strength level.