第二代双源CT双能扫描头颈部CT血管成像不同造影剂用量的比较

Dual-energy Computed Tomographic Angiography of Head and Neck Arteries with Different Contrast Material Doses in Second Generation Dual-source Computed Tomography System

目的探索第2代双源CT双能扫描头颈部CT血管成像减少造影剂用量的可能性。方法将57例进行头颈部CT血管成像检查的患者分为A、B、C3组,每组给予不同剂量的高浓度造影剂和48ml生理盐水,并采用不同的延迟时间。假设小剂量团注测试计算的达峰时间为Ts。A、B及C组的造影剂用量分别为40、45及50ml,延迟时间分别为(T+1)、(T+1)及(T+2)s。分别测量各组患者的主动脉弓、上腔静脉、双侧颈总动脉分叉、双侧大脑中动脉M1段、基底动脉、直窦强化程度的CT值,以及造影剂注射对侧颈内静脉(颈内动脉分叉水平)的CT值。采用4分法评价颈部静脉对动脉的影响及颅内动脉分支的显示情况。结果除A组患者颈内静脉及直窦的强化程度均低于其余两组外(P<0.05),其余3组患者的目标血管强化程度差异均无统计学意义。3组患者颈部静脉影响及颅内动脉分支显示情况的评分差异均无统计学意义。结论第2代双源CT双能扫描头颈部CT血管成像使用小剂量团注测试估测扫描的延迟时间,能减少造影剂用量,并且得到比较好的图像质量。

Objective To explore the feasibility of a dual-energy computed tomographic angiography （DECTA） protocol using test-bolus injection with reduction of contrast material（CM） dose in second generation dual-source CT system.Methods Totally 57 consecutive patients underwent CT angiography scan covering the cervical and cerebral arteries.CT was performed with second generation dual-source CT system.The time to peak （T） using a test-bolus injection was calculated.The patients were divided into three groups （A,B,and C） with different CM doses （40,45,and 50 ml） and different delay time points [（T＋1）,（T＋1）,and （T＋2）s].All the patients were followed by a 48 ml saline flush.Arterial enhancements were quantified by measuring attenuation values of the aortic arch,bifurcation of common carotid artery,contralateral internal jugular vein of the CM injection,superior vein cava,proximal middle cerebral artery,basilar artery,and straight sinus on source images.Visualizations of intracranial artery and ipsilateral venous effect of the CM injection were rated on a four-point grading scale on CTA images for qualitative assessment.Results Although the attenuation of internal jugular vein and straight sinus were significantly lower in group A than in groups B and C （P0.05）,the attenuation of aortic arch,superior vein cava,common carotid artery,middle cerebral artery,and basilar artery vessels showed no significant differences among these three groups.The scores of the visualizations of intracranial artery and ipsilateral venous effect of the CM injection were also not significantly different among these three groups.Conclusion Based on the delay time calculated by a test-bolus injection,a reduced-dose contrast material may provide an equal degree of arterial attenuation and a lower attenuation of vein for dual-engergy CTA covering the craniocervical region in second generation dual-source CT system.