双低剂量冠状动脉CT血管成像在筛选老年冠心病中的应用价值

Application value of dual-low-dose coronary CT angiography in screening the elderly with coronary heart disease

目的评估应用128层螺旋CT(u CT 760)结合Karl 3D迭代技术进行低管电压、低对比剂碘摄入量冠状动脉CTA检查在老年群体的临床应用价值。方法前瞻性连续选取身体质量指数(BMI)在20～25 Kg/m^2临床怀疑或已知冠心病拟行冠状动脉CTA检查的200例老年患者。按随机数字表法选取60例为对照组(A组),其余140例为试验组(B组)。2组均行冠状动脉CTA检查,A组采用管电压120 kVp,碘对比剂浓度350 mgI/mL。B组再根据管电压和碘对比剂不同分为2个亚组,低剂量组B1组(60例)采用80 kVp、350 mgI/mL碘对比剂,双低剂量组B2组(80例)采用70 kVp、300 mgI/mL碘对比剂。并分别采用滤波反投影法(FBP)(A组)和Karl 3D迭代重建技术(B组)进行图像重建。对各组CT图像的辐射剂量[CT剂量容积指数(CTDIvol)和有效剂量(ED)]以及图像噪声(SD)、图像信噪比(SNR)、冠状动脉近段的对比噪声比(CNR)、对比剂碘摄入量进行系统测量。每例患者的冠状动脉CTA图像质量由2名放射科医师采用双盲法进行4分法主观评分。应用ANOVA单因素方差分析比较3组辐射剂量(CTDIvol和ED)、SD、SNR和冠状动脉近段CNR。采用秩和检验比较各组图像的主观评价指标差异。用Kappa检验评价2名观察者冠状动脉图像质量评分的一致性。结果 A组、B1组、B2组的CTDIvol分别为(17.81±0.92)mGy、(5.99±0.60)mGy和(4.87±1.35)mGy,ED分别为(3.59±0.15)m Sv、(1.21±0.13)m Sv和(0.97±0.29)m Sv,3组间两两比较差异有统计学意义(P<0.05)。A组、B1组、B2组在主、客观图像质量评分上差异无统计学意义(P>0.05)。双低剂量B2组较常规剂量A组对比剂碘摄入量减少了21.4%。结论 128层螺旋CT采用低管电压、低对比剂碘摄入量在老年群体中行冠状动脉CTA检查,通过结合Karl 3D迭代技术,在保证图像质量的前提下,可以有效降低辐射剂量及对比剂碘摄入量,从而达到老年群体低剂量冠状动脉成像的目的。

Objective To investigate the clinical application value of dual low dose coronary computed tomography angiography(CCTA)on 128 slices CT(uCT 760)usingKarl 3Diterative reconstruction technique(IRT)in elderly population.Methods Two hundred sequential patients with normal BMI(20-25 kg/m^2)who were suspected coronary heart disease(CHD)or had been diagnosed CHD underwent coronary CT angiography.Two hundred patients were divided into 2 groups at random:controlgroup(groupA)and experimental group(groupB).The tube voltage/Iodine contrast agent concentration was 120 kVp/350 mg/mL ingroup A.Group B was divided into the following two subgroups according to different tube voltage and Iodine contrast agent concentration:group B1(80 kVp/350 mg/mL),group B2(70 kVp/300 mg/mL).The imaging data were reconstructed by FBP(group A)orKarl IRT(group B).Two blinded readers graded image quality on a 4-point Likert scale.The differences in image noise,signal-tonoise ratio(SNR)contrast-to-noise ratio(CNR),CT dose volume index(CTDIvol),effective dose(ED),and image quality between the groups were compared by using ANOVA or ranks test.Results The CTDIvol and ED were respectively(17.81±0.92)mGy,(5.99±0.60)mGy,(4.87±1.35)mGy and(3.59±0.15)mSv,(1.21±0.13)mSv,(0.97±0.29)mSv.There were significant differences of the CTDIvol and EDbetween group A,group B1 and group B2(P<0.05).There was no significant difference in subjective and objective image quality scores among the three groups(P>0.05).Compared with the conventional dose group,the dose of iodine contrast agent in low-dose group B2 decreased by 21.4%.Conclusion Dual low dose CCTA on 128 slices CT,by usingKarl 3DIRT,can effectively reduce the radiation dose and contrast agent iodine intake without compromise of image quality,and achieve the purpose of low-dose coronary angiography in the elderly population.