低剂量对比剂头颈部CT血管成像

目的探讨低剂量对比剂头颈部CTA成像的可行性。方法根据对比剂剂量和流率,将67例接受头颈部CTA的患者对比剂均为碘帕醇(370mgI/ml)]随机分为2组:常规组(n=33)以固定流率(4ml/s)注入90ml对比剂和20ml生理盐水,个体化组(n=34)根据公式计算所需对比剂剂量和流率对比剂剂量(ml)=体质量(kg)×λ(ml/kg);流率(ml/s)=对比剂剂量/(曝光时间+7);生理盐水剂量(ml)=(27.5-7-曝光时间)×流率。患者体质量为45～60kg时,λ=0.8ml/kg;61～75kg时λ=0.9ml/kg;>75kg时λ=1.0ml/kg]。测量主动脉弓、双侧颈总动脉分叉和双侧大脑中动脉起始段相应层面的增强CT值。采用单因素方差分析比较CT值和对比剂剂量,以t检验比较两组大脑中动脉图像质量。结果常规组和个体化组主动脉弓CT值分别为(414.20±6.24)HU、(435.36±6.44)HU(P<0.001);右颈总动脉分叉处CT值分别为(434.29±6.25)HU、(459.85±6.48)HU(P<0.001);左颈总动脉分叉处CT值分别为(435.42±6.26)HU、(458.43±6.42)HU(P<0.001)。常规组和个体化组右大脑中动脉起始段CT值分别为(291.03±10.08)HU、(267.55±9.88)HU(P=0.180);左大脑中动脉起始段CT值分别为(289.94±9.80)HU、(269.50±9.86)HU(P=0.169)。常规组每例对比剂剂量均为90ml,个体化组平均剂量为(59.41±7.91)ml(F=508.474,P<0.001)。常规组大脑中动脉图像质量等级优秀、良好和一般分别为28、4和1例,个体化组分别为27、6和1例(P=0.874)。结论通过个体化解决方案,降低头颈部CTA成像的对比剂剂量是切实可行的。

Feasibility of head and neck CT angiography with low dose contrast medium

Objective To observe the feasibility of head and neck CTA with low dose contrast medium.Methods Sixty-seven patients who underwent head and neck CTA were randomly divided into 2 groups according to different contrast medium dosage and flow rate.MSCTA was performed using iopamidol（370 mgI/ml）.In the routine group（n=33）,an option of regular flow rate（4 ml/s） and injection volume（90 ml） of contrast medium and 30 ml of saline were performed.In the individualized group（n=34）,the contrast medium dosage and flow rate were determined according to the formula as follows： Contrast medium dosage（ml）=body mass（kg）×λ（ml/kg）;flow rate（ml/s）=contrast medium dosage/（7＋s）;saline dosage（ml）=（27.5-7-s）× flow rate.In the formula,s meant CT scanning time,and λ value was determined by varied body mass（kg,λ=0.8 ml/kg;kg,λ=0.9 ml/kg;75 kg,λ=1 ml/kg）.Measurements of ROI＇s attenuation were performed and compared in the aorta,bilateral carotid artery bifurcation and bilateral middle cerebral artery（MCA） initial part.CT attenuation and contrast medium dosage in each group was analyzed with one-way ANOVA.Image quality of MCA was analyzed with One-Samples Test（t-test）.Results CT values for the aorta was（414.20±6.24）HU and（435.36±6.44）HU（P0.001）,for right carotid artery bifurcation was（434.29±6.25）HU and（459.85±6.48）HU（P0.001）,and for left carotid artery bifurcation was（435.42±6.26）HU and（458.43±6.42）HU（P0.001） in the routine group and the individualized group,respectively.However,no statistical difference was found in the aspects of the CT value for the right MCA initial part（291.03±10.08]HU vs 267.55±9.88]）HU,P=0.180）,nor for the left MCA initial part（289.94±9.80]HU vs 269.50±9.86]）HU,P=0.169）.In the individualized group,the contrast medium dosage was significantly lower than that of the routine group on average（90 ml vs 59.41±7.91]ml,F=508.474,P0.001）.Image quality of MCA in routine group was rated as excellent in 28 cases,good in 4 and ordinary in 1,while was excellent in 27,good in 6 and ordinary in 1 case in individualized group（P=0.874）.Conclusion With individualized scanning solution,the application of lower contrast medium dosage is practically feasible in in head and neck CTA.