双低剂量联合低流速注射在双源CT冠状动脉血管成像中的应用

Double low dose combined with low velocity of flow injection in the application of the dual-source CT coronary angiography

目的探讨低管电压和低剂量对比剂、低流速注射在双源CT前瞻性心电触发大螺距扫描进行冠状动脉成像的可行性。方法选取120例体质量指数(BMI)18.6~24.9 kg/m^2和心率<65次/min的患者,A组60例采用120 kV管电压、对比剂剂量0.9 ml/kg、注射流速5.0 ml/s进行前瞻性心电触发门控扫描;B组60例采用80 kV管电压、对比剂剂量0.7 ml/kg、注射流速3.5 ml/s进行前瞻性心电触发大螺距扫描。对比剂均采用碘海醇350 mg I/ml,图像重建均采用迭代重建技术(SAFIRE)。测量2组的CT强化值和噪声,计算信噪比(SNR)、对比噪声比(CNR)。采用双盲法对冠状动脉以4分法进行评价,其中1分为不可诊断图像。结果 A组管腔内的平均强化CT值略高于B组,B组的图像噪声较A组略高,A组的SNR、CNR高于B组,差异均无统计学意义(P>0.05)。B组有效辐射剂量[(0.39±0.02)mSv]较A组显著降低[(4.99±1.36)mSv],差异有统计学意义(P<0.01)。结论在BMI 18.6~24.9 kg/m^2、心率<65次/min的患者中,应用双源CT前瞻性心电触发大螺距、低管电压、低对比剂剂量、低流速注射扫描,图像重建采用迭代重建,能够在保证冠状动脉图像质量的情况下,大幅度降低辐射剂量。

Objective To discuss the feasibility of lower tube voltage and low dose of iodineconcentration contrast material,low velocity of flow injection in dual-source CT prospective ECG-trigger high pitch to scan for coronary artery imaging.Methods Selected 120 cases patients of body mass index(BMI) of 18.6 to 24.9 kg/m^2,and heart rate<65 bpm.A group of 60 patients used 120 kV tube voltages,contrast media dosage 0.9 ml/kg,and injection rate of 5.0 ml/s to carry out prospective ECG-trigger scanning.B group of 60 cases used 80 kV tube voltage,contrast media dosage 0.7 ml/kg,injection rate of 3.5 ml/s to carry out prospective ECG-trigger high-pitch scan.Adopt iodine contrast media(Iohexol 350 mg I/ml) and iterative reconstruction technique(SAFIRE) was used in image reconstruction.Measured the values of CT enhanced images and noise of two groups,calculated the signal-to-noise ratio(SNR) and contrasted to noise ratio(CNR).The method of double blind was used to evaluate coronary artery in 4-point scale(1=non-diagnostic,4=excellent).Results The average enhanced CT attenuation of coronary artery in group A was slightly higher than group B;The image noise of group B was slightly higher than group A;SNR,CNR of group A was higher than group B,the difference was not statistically significant(P>0.05).Group B effective radiation dose(0.39±0.02)m Sv was significantly lower in group A(4.99±1.36)m Sv and had statistically significant difference(P<0.01).Conclusion In the patients of BMI 18.6 to 24.9 kg/m^2,HR<65 bpm,the application of dual-source CT prospective ECG-trigger and high pitch,low voltage,low dose contrast media,low velocity of flow injection,image reconstruction using iterative reconstruction,can guarantee the quality of coronary artery image,and radiation dosage significantly reduces 91.8%.