自适应统计迭代重组算法提高肿瘤患者腹部增强CT图像质量的研究

A study of using adaptive statistical iterative reconstruction-V to improve the image quality of abdominal enhanced CT for patients with malignant tumor

目的探讨肿瘤患者腹部增强CT图像质量与自适应统计迭代重组(ASIR)-V迭代率的关系。方法试验组肿瘤患者22例,腹部双期增强CT扫描,滤波反投影(FBP)及迭代重建技术ASIR-V(迭代率0～100%,间隔20%)图像重建。对图像质量进行客观评价和主观评分,评估最佳迭代率,记录扫描有效辐射剂量(ED)。验证组肿瘤患者15例,采用试验组所得的最佳迭代率行腹部双期增强CT扫描,对图像质量进行评分并记录ED。采用单因素方差分析比较试验组不同迭代率之间CT值和噪声值,采用秩和检验(Kruskal-Wallis法)比较图像质量主观评分,采用秩和检验(Friedman法)比较两组间同等迭代率水平下图像质量评分,采用独立样本t检验比较ED值。结果各器官不同迭代率图像间CT值差异无统计学意义(P均>0.05),噪声值差异有统计学意义(P均<0.05),噪声值随迭代率增加而减小。不同迭代率图像评分差异有统计学意义(P均<0.05),迭代率为40%图像质量评分最高,为(4.59±0.50)分。验证组图像质量评分为(4.61±0.50),同等迭代率水平两组间图像质量差异无统计学意义(P>0.05)。两组ED值分别为(11.28±3.05)分和(7.44±1.37)分,差异有统计学意义(P<0.05)。结论肿瘤患者的腹部增强CT检查推荐使用ASIR-V迭代率40%,以保障图像质量,并降低患者的有效辐射剂量。

Objective To determine the optimal percent of ASIR-V in abdominal enhanced CT for patients with malignant tumor. Methods Twenty-two patients with history of malignant tumor were prospectively enrolled as the experimental group and underwent a two-phase abdominal enhanced CT. Images were reconstructed with 0~100% ASIR-V in a step of 20%. For each of the reconstructed images, two radiologists made objective measurements and subjective evaluation of the image quality. The effective dose （ED） was also recorded for each patient. Then, another group of 15 patients with malignant tumor were prospectively enrolled as the validation group. The optimal weight of ASIR-V obtained from the experimental group was adopted in the scanning protocol. Image quality and ED were compared between the experimental and validation group. Results No statistical difference was found in CT values among images reconstructed with different weights of ASIR-V （ P 〉0.05）. Image noise decreased with the increase of ASIR-V （ P 〈0.05）. Image quality score at first increased with ASIR-V then decreased. The highest score was associated with 40% ASIR-V. For the validation group, while the image quality score was not different from the experimental group, ED was significantly reduced （11.28±3.05 vs. 7.44±1.37, P 〈0.05）. Conclusion 40% ASIR-V is recommended for abdominal enhanced CT for patients with abdominal malignant tumor, thery improving the image quality and reducing the radiation dose.