ASIR技术对肝脏增强CT检查图像质量及辐射剂量影响的自身对照研究

The Influence ASIR Technique on the Hepatic Enhanced CT Image Quality and Radiation Dose:A Self-Control Study

目的分析自适应统计迭代重组（ASIR）技术在降低肝脏增强CT扫描中辐射剂量的作用。方法选取42例行肝脏增强CT检查患者，在3～9个月先后行2次CT扫描。分别行传统的滤过反投影法（FBP）和ASIR技术重组图像。比较2种重组技术在肝实质和腹主动脉内的噪声以及主观图像质量，测量比较两次检查肝脏的CT容积剂量指数（CTDIvol）与有效辐射剂量（ED）。结果42例受检者FBP重组CTDIvol和ED分别为（16．2±9）mGy、（7．9±5．8）mSv；ASIR重组CTDIvol和ED分别为（9．8±5．3）mGy、（4．8±2．6）mSv，两次检查的剂量差异有统计学意义（P〈0．05）。低剂量ASIR技术成像噪声要低于常规剂量FBP成像噪声（P〈0．05）。主观图像质量评分无统计学意义（P〉0．05）。结论与传统CT重组图像的FBP相比，ASIR技术在肝脏增强CT扫描中辐射剂量可显著降低，而图像噪声却显著降低。

Objective To analyze the effect of adaptive statistical iterative reconstruction （ASIR） technique on the reduction of radiation dose in hepatic contrast-enhanced CT scanning, and to compare this technique with routine dose hepatic CT scanning with filtered back projection （FBP）. Methods A total of 42 patients were enrolled in this study, including 27 males and 15 females. Two times of CT scanning were performed in all patients within 3 - 9 months. The images were reconstructed with FBP and ASIR separately. The image noise in abdominal aorta and the subjective image quality were determined, and the results were compared between the two techniques. The volume CT dose index （ CTDIvol ） and the effective dose （ED） were calculated. Results Using FBP reconstruction technique the mean CTDIvol and ED were （ 16.2 ± 9） mGy and （7.9 ± 5.8 ） mSv respectively, while using ASIR technique the mean CTDIvol and ED were （9.8 ± 5.3 ） mGy and （4.8 ± 2.6） mSv respectively. The differences between the two techniques were statistically significant （P 〈0.05 ）. The image noise of low-dose ASIR technique was lower than that of routine dose FBP technique （ P 〈 0.05 ）. No statistically significant difference in subjective image quality existed between the two techniques （ P 〉 0.05 ）. Conclusion Compared with conventional fihered back projection CT image reconstruction technique, ASIR technique can strikingly decrease the radiation dose and reduce the image noise in hepatic enhanced CT scanning.