低管电压、低碘浓度对比剂及迭代重建在冠状动脉CT血管成像中的应用

Application feasibility of low tube voltage and lower iodine concentration contrast medium as well as iterative reconstruction in coronary computed tomography angiography

目的 探讨行冠状动脉CT血管成像（CCTA）检查时,低管电压（100 kV）、低碘浓度（270 mgI/ml）对比剂及迭代重建在降低辐射剂量和碘对比剂用量的同时,保持图像质量的可行性.方法 连续入选2013年1至5月行CCTA检查的疑诊冠心病患者80例,将患者分为两组：对照组（40例）采用常规方案,即管电压采用120 kV,碘对比剂浓度为370 mgI/ml,采用滤波反投影法重建,重建卷积核为B26f;试验组（40例）管电压采用100kV,碘对比剂浓度为270 mgI/ml,采用迭代重建,重建卷积核为I26f.其他扫描和对比剂注射参数两组间完全一致.对两组的图像进行重建、测量和质量评分,并计算碘用量和有效辐射剂量.结果 对照组和试验组患者的体质指数分别为（25.3±3.0） kg/m2和（25.4±3.0） kg/m2（P=0.852）,图像信噪比分别为22.2 ±5.5和23.6±5.8（P=0.277）,对比度噪声比分别为35.6±17.6和41.1±17.6（P =0.163）,图像质量分别为（4.70 ±0.52）分和（4.63±0.59）分（P =0.545）.对照组和试验组碘用量分别为（25.27±0.94）g和（18.49±0.75）g（P ＜0.001）,试验组较对照组少26.8％.对照组和试验组的有效辐射剂量分别为（3.52±1.16） mSv和（2.31±0.73） mSv（P ＜0.001）,试验组较对照组少34.4％.结论 行CCTA检查时,采用低管电压、低碘浓度对比剂和迭代重建可以在保持冠状动脉图像质量不降低的基础上,显著减少碘对比剂用量及有效辐射剂量.

Objective To investigate the feasibility of using lower iodine concentration 270 mgI/ml） contrast medium,lower X-ray tube voltage （100 kVp） and iterative reconstruction （IR） to reduce both iodine load and radiation dose but keep the image quality of coronary CT angiography （CCTA）.Methods A total of 80 consecutive patients with suspected coronary artery disease were prospectively assigned to one of two groups via computer central system from January to May 2013.The control group （n =40） was scanned using dual-source CCTA protocols of 120 kV,370 mgI/ml Iopromide and filtered back projection reconstruction with a vascular algorithm （B26f）.The study group （n =40） was scanned using 100 kV,270 mgI/ml Iodixanol and sinogram affirmed iterative reconstruction with a vascular algorithm （I26f）.Other scan parameters and contrast injection protocol were similar between the two groups.Attenuation in the ascending aorta and coronary arteries along with image noise were measured.Images were reconstructed,measured and graded,and iodine load and effective radiation dose were calculated.Results The body mass index （（25.3 ± 3.0） kg/m2 vs.（25.4 ± 3.0） kg/m2,P =0.852）,image quality scores （4.70 ±0.52 vs.4.63 ±0.59,P =0.545）,mean signal-to-noise ratios （22.2 ±5.5 vs.23.6 ± 5.8,P =0.277）,and contrast-to-noise ratios （35.6 ± 17.6 vs.41.1 ± 17.6,P =0.163） were similar between the control group and study group.Mean iodine loads were significantly reduced in the study group （（18.49 ± 0.75） g） compared to control group （（25.27 ± 0.94） g）,P ＜ 0.001）.Mean effective radiation doses were also significantly reduced in the study group （（2.31 ± 0.73） mSv） compared to that in control group （（3.52 ± 1.16） mSv）,P ＜ 0.001）.Conclusion Use of low X-ray tube voltage and iterative reconstruction allows lower iodine load and effective radiation dose application at CCTA without image quality reduction.