Objective To investigate clinical application of the coronary computed tomographic angiography ( CCTA) by using low dose scanning technology and low concentrative contrast medium on dual -source CT.Methods 120 patients were randomized two groups (group A and group B), According to BMI <25.0 kg/m2, sixty-four patients in group A were divided two groups (group A1 and group A2), 32 patients in group A1, 32 patients in group A2.All patients in group A were examined with 80 kV. According to BMI≥25.0 kg/m2, fifty-six patients in group B were divided two groups (group B1 and group B2), all patients in group B were examined with 100 kV.The contrast medium that group A 1 and B1 used was visipaque (270 mgI/ml GE company) , while, A2 and B2 was mnipaque (350 mgI/ml GE company).The subjective and objective evaluation index (vascular CT value and image noise , signal to noise ratio ( SNR ) , contrast to noise ratio ( CNR ) and total radiation dose , iodine dosage of four groups of image were analyzed .SPSS 19.0 statistical software was used to analyze data .Results The general data of four groups of patients had no statistical significance ( P >0.05), the total iodine difference was statistically significant ( P <0.05).As for group A1 contrast group A2, group B1 contrast group B2, iodine total amount were reduced by 5243 mg, 8012 mg, respectivly. Between group A and B, ED, CTDIvol, DLP difference was statistically significant ( P <0.05).In group A, the ED decreased about 45.9%than group B.The subjective evaluation of four groups of image had no statistical significance ( P >0.0167).Be-tween group A1 and A2, group B1 and B2, the CT value of AA, RCA, LM vessel , SNR, CNR ifference was statistically signifi-cant ( P <0.05), the difference of noise has no statistical significance ( P >0.05).Conclusion On the platform of siemens somatom definition definition flash CT machine , A normal BMI group with 80 kV, overweight group with 100 kV were combined with low concentration of contrast medium injection scheme , can not only reduce the radiation dose and dosage of contrast agent obviously , but also obtain satisfactory image used for clinical diagnosis .%目的：探讨双源CT低管电压加低浓度对比剂扫描技术在冠状动脉成像中的临床应用。方法120例患者根据体质量指数（body mass index， BMI）分为A、B两组，A组64例，BMI＜25．0kg／m2，随机分为A1、A2两组，各32例，扫描条件：80kV；B组56例，BMI≥25．0kg／m2，随机分为B1、B2两组，各28例，扫描条件：100kV。 A1、B1组采用对比剂威视派克270 mgI／ml；A2、B2组采用对比剂欧乃派克350 mgI／ml。对四组图像主观评价、客观评价指标（血管CT值、图像噪声、信号噪声比（ signal-to-noise ratio， SNR）、对比噪声比（ contrast-to-noise ratio， CNR））及辐射剂量、碘总量进行对比分析。应用SPSS 19．0统计软件对数据进行分析。结果 A1、A2及B1、B2组患者一般资料无统计学意义（ P ＞0．05），碘总量差异有统计学意义（ P ＜0．05），A1比A2组、B1比B2组碘总量分别降低了5243mg、8015mg。 A组与B组ED、CTDIvol、DLP差异有统计学意义（ P ＜0．05），A组较B组ED降低约45．9％。四组图像主观评价差异无统计意义（ P ＞0．0167）。A1、A2组及B1、B2组AA、RCA、LM血管CT值、SNR、CNR差异有统计学意义（ P ＜0．05），AA、RCA、LM血管噪声无统计学意义（ P ＞0．05）。结论在西门子Somatom Definition Flash CT 机平台上，BMI正常及超重患者分别在80KV、100KV条件下联合低浓度对比剂注射方案可明显降低患者辐射剂量及碘用量，图像质量满意，可满足临床诊断。
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