128层双源CT联合低管电压及低剂量对比剂在法洛四联症患儿血管成像中的应用

Application of low tube voltage and low volume contrast medium protocol on 128-slice dual-source CT in children with tetralogy of Fallot

目的探讨128层双源cT联合低管电压和低剂量对比剂在法洛四联症（TOF）患儿血管成像中的应用。方法前瞻性收集TOF患JL40例，按照随机数字表法等分为A、B两组，管电压和对比剂用量分别为80kVp、1．2ml／kg（A组），70kVp、1．0ml／kg（B组），对比剂注射时间均固定为12s。测量两组患儿图像升主动脉近端、肺动脉主干及左、右心室的cT值、噪声及信噪比，并对图像质量进行主观评分，同时记录两组患儿的辐射剂量及对比剂用量。组间各测量部位的cT值、噪声、信噪比及组间辐射剂量、对比剂用量的差异采用两样本t检验进行比较，组间图像质量主观评分的差异采用Mann-WhitneyU秩和检验进行比较。结果40例患儿均顺利完成检查，两组间各测量部位的cT值、噪声、信噪比及图像质量主观评分差异均无统计学意义（P值均〉0．05），A、B两组有效辐射剂量分别为（0．17±0．05）、（0．13±0．04）mSv，对比剂用量分别为（10．00±1．84）、（8．29±1．45）ml，两组间差异均具有统计学意义（t值分别为2．48、2．89，P值均〈0．05）。结论TOF患儿128层双源CT血管成像联合低管电压和低剂量对比剂可获得满意的图像质量，可降低辐射剂量及对比剂用量，具有良好的临床应用价值。

Objective To investigate the effectiveness and feasibility of cardiovascular computed tomography artgiography（CTA） in 128-slice DSCT with low tube voltage and low dosage contrast media in children with tetralogy of Fallot （TOF）. Methods Forty patients with TOF were randomly divided into group A and group B by random number table method, patients in group A received a conventional scan with 80 kVp and contrast media of 1.2 ml/kg, patients in group B, 70 kVp and contrast media of 1.0 ml/kg were used. The injection time of the two groups were both fixed for 12 s. CT attenuation, image noise and signal-to-noise ratio （SNR） of ascending aorta, the main pulmonary artery, left ventricle and right ventricle were quantified. Radiation dose and volume of the contrast medium were recorded. Subjective image quality was assessed by two radiologists in consensus. The Student＇s t test was performed to analyse the differences between the two groups regarding CT attenuation, image noise, SNR, radiation dose and volume of the contrast medium. The image quality scores between the two groups were compared by using the Mann-Whitney U test. Results No significant difference was found in the attenuation, noise, SNR between the two groups in the same evaluated anatomic regions and no significant difference was found in the image quality. Effective dose （ED） was （0.17±0.05）, （0.13±0.04）mSv respectively, there was significant reduction in group B than that in group A （t=2.48, P=0.019）. The consumed iodine amount was （10.00±1.84）, （8.29± 1.45） ml respectively, there was significant reduction between the two groups （t=2.89, P=0.007）. Conclusions In children with TOF, the cardiovascular CTA with diagnostic quality can be adequately acquired with low tube voltage （70 kVp） and low concentration contrast media （1.0 ml/kg）, there is significant reduction in radiation dose and contrast medium amount.