目的 探讨“双低”血管成像技术-低千伏、低对比剂用量应用于临床头颈部血管成像的可行性。方法 采用35ml的 低对比剂用量用于头颈部CT血管成像，将20例临床疑似头颈部血管疾病患者随机分为2组，实验组10例采用80KV进 行头颈部血管成像扫描，对照组10例采用常规120KV，两组的对比剂用量均为35ml，注射速率为5ml/s，注射完毕后 同等速率注入生理盐水40ml；均采用自动管电流调节技术(Caredose 4D)，迭代算法(SAFIRE)重建，根据原始图像 及最大密度投影像(MIP)，比较不同千伏血管强化程度，不同KV下的辐射剂量、脑实质的密度及信号噪声比(SNR)、 对比噪声比(CNR)、噪声等，并对其进行统计学分析。结果 实验组和对照组图像质量评分分别为5.833±0.100和 5.856±0.133，P=0.694＞0.05；图像噪声分别为2.261±0.026和2.522±0.031(P=0.000＜0.05)，噪声明显增加； 辐射剂量分别为412.4±49.2和101.8±11.6，P=0.000＜0.05，辐射剂量显著下降。结论 采用“双低”技术进行头 颈部CT血管造影，所得图像能满足影像诊断，且大为减少辐射剂量和对比剂用量，可望用于头颈部CT血管成像筛查 和治疗后复查，值得临床进一步深入研究和推广应用。

Objective To assess the feasibility of the “double- low” CT angiography - low-kilovolt and low contrast agent dose in cerebral and neck angiography. Methods In this study, low contrast agent dose-35ml would be used in cerebral and neck CT angiography. Twenty patients, clinically suspected the insufficiency of head-and-neck artery, were divided into two groups. One group (10 patients)took the conventional tube voltage-120KV,while the other group(10 patients)took the 80KV tube voltage, both the amount of contrast agent were 35ml, and the injection rate was 5ml/s, then injected 40ml saline with the same rate. Both of two groups take auto- Care dose 4D and Safire reconstruction, according to the original images and Maximum intensity projection(MIP), comparing the display of the vessels in cerebral and neck , calculating the radiation dose, and the density, noise, signal-to-noise ratio, contrast-to-noise ratio of the parenchymal with different kilovolts, then take statistical analysis. Results The qualities of the images to both of the groups respectively are 5.833±0.100 and 5.856±0.133, P=0.694>0.05; Noise of the images respectively is 2.261±0.026 and 2.522±0.031,P=0.000<0.05, the noise is markedly increased; The radiation doses are 412.4±49.2 and 101.8±11.6, P=0.000<0.05, the radiation doses are dramatic declined. Conclusion With the use of “double-low” in dual-energy CT in cerebral and neck angiography, not only ensuring the images could be used to the clinical diagnose, but also reducing the radiation dose and the contrast agent dosage; In cerebral and neck angiography, it is hopefully used in the screening and reexamination during therapy, and it is worthy of further study and application.