正弦图确定迭代重建应用于肠道低剂量CT增强扫描的可行性研究

目的:探讨应用迭代重建进行肠道低剂量CT增强扫描的可行性.方法:首先通过水模预实验确定最佳低剂量扫描参数,然后搜集80例拟行肠道CT增强扫描且体质量指数(BMI)＜25 kg/m2的患者,随机纳入常规剂量滤过反投影(filtered back projection,FBP)重建组和低剂量正弦图确定迭代重建(sinogram affirmed iterative reconstruction,SAFIRE)组.由2位放射科医师采用盲法对2组图像质量进行主观评分;测量图像噪声、信噪比(signal to noise ratio,SNR)及对比噪声比(contrast to noise ratio,CNR);记录2组的容积CT剂量指数(volume CT dose index,CTDIvol)、剂量长度乘积(dose-length product,DLP),计算有效辐射剂量(effective dose,ED).最后对2组患者的各评价指标进行统计分析.结果:低剂量组与常规剂量组相比,主观图像质量评分、各兴趣区的图像噪声、SNR和CNR均无统计学差异(P＞0.05).低剂量组辐射剂量(5.31±0.87)mSv显著低于常规剂量组(9.37±1.89)mSv(P＜0.001).结论:联合应用低剂量CT扫描和迭代重建技术进行肠道CT增强扫描能够在显著减少辐射剂量的同时,获得与常规剂量FBP重建相近的图像质量.

Feasibility of low-radiation-dose contrast-enhanced CT for bowel examinations with sinogram affirmed iterative reconstruction

Objective To evaluate the feasibility of iterative reconstruction in low-dose contrast-enhanced bowel CT. Methods Eighty patients with body mass indexes （BMI） less than 25 underwent the contrast-enhanced bowel dual- source CT examination after the best scanning parameters were selected by preliminary experiment. The patients were randomly assigned into two groups. The 40 patients in the conventional group were scanned using 120 kV and recon structed with standard filtered back projection （FBP）. The 40 patients in the low-dose group were scanned using 100 kV and reconstructed with iterative reconstruction （SAFIRE）. The subjective image quality score, image noise, signal to noise ratio （SNR）, contrast to noise ratio （CNR） and effective dose （ED） of each group were evaluated. Results There was no statistical difference in subjective image quality scores, image noise, SNR and CNR of every ROI between the con- ventional and low-dose group （P〉0.05）. Radiation dose was significantly lower in the low-dose group than that in the con- ventional group （9.37±1.89） mSv vs.（5.31±0.87） roSy, P〈0.001）. Conclusion Combining iterative reconstruction with low-tube-voltage technique, a bowel dual-source CT examination can still maintain the image quality, as well as sig-nificantly lower the radiation dose.