中文摘要：

目的 探讨肾动脉CTA中采用常规扫描和能谱成像扫描方案对图像质量和辐射剂量的影响.方法 前瞻性连续收集拟行肾动脉CTA检查的90例患者,按照数字表法随机分为A、B、C 3组,每组30例.A组采用普通扫描模式（管电压120 kVp、管电流30-650 mA、旋转时间0.5 s/周、扫描野50 cm×50cm）;B组和C组分别采用能谱扫描方案1（管电压80、140 kVp切换,管电流375 mA,旋转时间0.7 s/周,显示野36 cm×36 cm）和能谱扫描方案2（管电压80、140 kVp切换,管电流360 mA,旋转时间0.6 s/周,扫描野32 cm×32 cm）,各组均采用50%迭代重组算法2.0对图像进行处理.对图像质量进行客观评价（包括肾动脉CT值、噪声、信噪比和对比噪声比）和主观评分,并记录辐射剂量（CT剂量指数、剂量长度乘积和有效剂量）.采用方差分析或Kruskal-Wallis检验评价各组图像质量和辐射剂量的差异.结果 采用能谱模式图像的最佳单能量范围为49-56 keV.A、B、C 3组间肾动脉CT值、噪声、SNR及CNR的差异均有统计学意义（P〈0.05）,其中A组（普通扫描模式）组和B、C组（能谱扫描模式）的差异有统计学意义（P〈0.05）,B组和C组间的差异无统计学意义（P〉0.05）.A组图像的主观评分值低于B组和C组,差异有统计学意义（P〈0.05）,B组和C组间图像评分的差异无统计学意义（P〉0.05）.A、B、C组的CT剂量指数、剂量长度乘积和有效剂量差异均有统计学意义（P〈0.05）,有效剂量分别为（8.2±1.2）、（5.2±0.9）和（4.4±0.7）mSv.结论 采用能谱扫描方案在保证肾动脉CTA图像质量的同时能降低辐射剂量,推荐使用能谱扫描方案2.

英文摘要：

Objective To compare the image quality and radiation dose of CTA of the kidney in patients using routine CT and the spectral imaging combination of different scanning protocols with the adaptive statistical iterative reconstruction 2.0 algorithm （ASIR 2.0）. Methods A total of 90 patients who had undergone a CTA of the kidney were divided into three groups （A, B and C）, with 30 patients in each group. Group A underwent a routine CT examination, and the scan parameters are：120 kVp, 30 to 650 mA, rotation time 0.5 s/r, scan FOV 50 cm × 50 cm;while groups B and C underwent spectral imaging protocol 1 and 2, the scan parameters of spectral imaging protocol 1 and 2 are：rapid dual kVp （80-140 kVp） switching in 0.25 ms, 375 mA and 360 mA, rotation time 0.7 s/r and 0.6 s/r, scan FOV 36 cm × 36 cm and 32 cm × 32 cm, respectively. All images were reconstructured using ASIR 2.0. The signal-to-noise ratio （SNR） and contrast-to-noise ratio （CNR） of all images were calculated when the kidney CTA was completed. Each subjective image evaluation used a 5-point scoring method and was conducted by two independent radiologists. The CT dose index （CTDIvol） and dose-length product （DLP） were recorded, and the mean value was calculated. The DLP was converted to the effective dose （ED）. All data were compared with Kruskal-Wallis test and one-way ANOVA. Results The energy level of 49 to 56 keV was found to provide the best CNR for displaying CTA of the kidney. There were significant differences in CT values, noise, SNR, CNR and subjective score between groups B, C and A （P〈0.05）, and there was no significant differences in CT values, noise, SNR, CNR and subjective score between groups B and C （P〉0.05）. There were significant differences in ED among groups A, B and C （P〈0.05）, and the ED of groups A, B and C were （8.2±1.2）, （5.2± 0.9） and （4.4 ± 0.7） mSv, respectively. Conclusion Spectral imaging with different scanning protocols can more effectively reduce the radiati