第三代双源CT冠状动脉、头颈动脉一站式CT血管成像:低剂量技术的应用价值

One-stop CT angiography of coronary artery,head and neck artery using the third generation dual-source CT:application value of low-dose technique

目的:探讨第三代双源CT低辐射剂量低对比剂用量在冠状动脉、头颈动脉一站式CT血管成像中的应用价值。方法:将临床怀疑冠状动脉和/或头颈动脉疾病的连续60例患者纳入研究,并随机分为低剂量组(A组)30例和常规剂量组(B组)30例。两组均采用第三代双源CT前瞻性大螺距模式行冠状动脉、头颈动脉一站式CTA检查,A组采用70 kV管电压、30 mL对比剂的低剂量模式,B组采用100 kV管电压、40 mL对比剂的常规剂量模式。将A、B两组图像采用MPR、CPR、MIP和VR技术进行图像后处理。由两位放射科医师对两组的冠状动脉和头颈动脉的图像质量进行主观评分,以节段为单位测量冠状动脉、头颈动脉的CT值、图像噪声值,计算信噪比(SNR)和对比噪声比(CNR),并进行组间比较。比较两组中辐射剂量指标值(CTDIvol、DLP、ED)的差异。结果:A、B两组之间冠状动脉和头颈动脉的主观质量评分的差异无统计学意义(冠状动脉:Z=-0.257,P=0.797;头颈动脉:Z=-0.961,P=0.337);两组间SNR和CNR的差异无统计学意义(升主动脉SNR:t=-1.203,P=0.234;升主动脉CNR:t=-1.845,P=0.070;左冠状动脉主干SNR:t=-0.132,P=0.895;左冠状动脉主干CNR:t=-0.324,P=0.747;右冠状动脉SNR:t=-1.058,P=0.294;右冠状动脉CNR:t=-1.251,P=0.216;颈总动脉SNR:t=-0.796,P=0.429;颈总动脉CNR:t=-0.561,P=0.577;椎动脉V1段SNR:t=0.407,P=0.685;椎动脉V1段CNR:t=0.521,P=0.604;颈内动脉SNR:t=-0.616,P=0.540;颈内动脉CNR:t=-0.516,P=0.608;基底动脉SNR:t=-0.442,P=0.660;基底动脉CNR:t=-0.325,P=0.746;大脑中动脉M1段SNR:t=0.790,P=0.443;大脑中动脉M1段CNR:t=-0.938,P=0.325);A组辐射剂量低于B组(CTDIvol:t=-20.40,P=0.000;DLP:t=-20.19,P=0.000;ED:t=-19.49,P=0.000)。结论:第三代双源CT低剂量在冠状动脉、头颈动脉一站式CT血管成像能提供高质量的图像质量,并能大幅减小辐射剂量和碘对比剂用量。

Objective:The aim of the study was to investigate the application value of one-stop CT angiography in coronary artery,head and neck artery using the third generation dual-source CT with low radiation dose and low contrast agent dose.Methods:A total of 60 consecutive patients with suspected coronary artery and/or head and neck artery diseases were enrolled in the study and randomly divided into 30 low-dose group(group A)and 30 conventional-dose group(group B),both group A and group B underwent one-stop CT angiography imaging of coronary artery,head and neck artery using the prospective ECG-triggered high-pitch scanning mode at a third generation dual-source CT.Group A adopted the low-dose mode of 70kV tube voltage and 30mL contrast agent,and group B adopted the conventional-dose mode of 100kV tube voltage and 40mL contrast agent.Images of group A and group B were reconstructed by MPR,CPR,MIP and VR technique respectively.Two radiologists subjectively rated the image quality of coronary artery,head and neck artery in two groups.CT atte-nuation values and image noise values of coronary artery,head and neck artery were measured in segments,and signal-noise ratio(SNR)and contrast-noise ratio(CNR)were calculated to obtain objective image quality.The differences of subjective score and objective image quality between the two groups were compared.The differences of radiation dose(CTDIvol,DLP,ED)between the two groups were compared.Results:There was no significant difference in subjective score of coronary artery,head and neck artery between group A and group B(coronary artery:Z=-0.257,P=0.797;head and neck artery:Z=-0.961,P=0.337).There was no significant difference in SNR and CNR between group A and group B(ascending aorta SNR:t=-1.203,P=0.234;ascending aorta CNR:t=-1.845,P=0.070;left main coronary artery SNR:t=-0.132,P=0.895;left main coronary artery CNR:t=-0.324,P=0.747;right coronary artery SNR:t=-1.058,P=0.294;right coronary artery CNR:t=-1.251,P=0.216;common carotid artery SNR:t=-0.796,P=0.429;common carotid artery CNR:t=-0.561,P=0.577;the V1 segment of the vertebral artery SNR:t=0.407,P=0.685;the V1 segment of the vertebral artery CNR:t=0.521,P=0.604;internal carotid artery SNR:t=-0.616,P=0.540;internal carotid artery CNR:t=-0.516,P=0.608;basilar artery SNR:t=-0.442,P=0.660;basilar artery CNR:t=-0.325,P=0.746;the M1 segment of the middle cerebral artery SNR:t=0.790,P=0.443;the M1 segment of the middle cerebral artery CNR:t=-0.938,P=0.325).The radiation dose of group A was significantly lower than that of group B(CTDIvol:t=-20.40,P=0.000;DLP:t=-20.19,P=0.000;ED:t=-19.49,P=0.000).Conclusion:Low-dose one-stop CT angiography of coronary artery,head and neck artery using third generation dual-source CT can provide high-quality image quality,and can greatly reduce the radiation dose and the amount of iodine contrast agent.