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【目的】评价应用低浓度对比剂在行冠状动脉CT血管造影（CTA）中的可行性。【方法】连续收集临床疑诊或确诊冠心病拟行冠状CTA，使用低浓度对比剂并采用前瞻性心电门控扫描者243例（观察组），按体质量指数（BMI）不同分为A组（100例）、B组（112例）和C组（31例），均使用低浓度对比剂（270mgI／mL），另外选择使用常规扫描（高浓度对比剂370mgI／mL，扫描电压120kV）的150例（对照组），按同样BMI分成三组进行配对比较，即A1、B1和C1组，每组各50例，比较各组辐射剂量（ED）、主动脉根部（AR）、左主干（LM）、右侧冠脉（RCA）近段CT值和标准差（SD），计算图像的信号噪声比（SNR）和对比噪声比（CNR）；并对所有病例的冠脉图像质量按节段进行评分。【结果】相同BMI、同样的对比剂浓度组之间的辐射剂量比较均有统计学意义（P＜0．05）；A组与A1组AR的CT值、图像噪声及SNR差异具有统计学意义（P＜0．05），两侧冠脉近段CNR差异无统计学意义（P＞0．05）；B组与B1组、C组与C1组间仅SNR差异有统计学意义（P＜0．05）；C组与C1组间可诊断率有显著差异（P＜0．05），而A组与A1组、B组与B1组比较差异无统计学意义（P＞0．05）。【结论】应用低浓度对比剂采用低管电压扫描能够获得满足诊断的冠脉CTA图像，可降低对比剂碘注射量及辐射剂量。“,”Objective]To evaluate the feasibility of coronary artery computed tomographic (CT ) angiography (CTA ) with low‐concentration contrast medium (CM) .[Methods]A total of 243 cases with clinically suspected or confirmed cor‐onary heart diseases and recommended for coronary CTA were consecutively collected .According to the body mass index (BMI) ,they were divided into group A ( n=100) ,group B ( n=112) and group C ( n=31) .Coronary CTA was per‐formed using prospective ECG‐gating scan modality with low tube voltage at 80 kv (group A) or 100kv (groups B and C) and low‐concentration CM (270 mgI/ml) .The values of exposure dose (ED) were calculated after CT examination .The average CT value and standard deviation (SD) of aortic root (AR) ,left main (LM) ,proximal segment right coronary ar‐tery (psRCA) and subcutaneous fat tissue (sFT ) were measured and then signal/noise ratio (SNR) and control noise ratio (CNR) calculated .And the image qualities of coronary artery were scored .Another 150 cases of contrast group were con‐secutively collected and divided into three groups according to the same BMI criteria .For contrast group ,conventional scanning parameters (fixed scan tube voltage at 120 kv and 370 mgI/ml CM ) were used .The enhanced CT value ,SNR , CNR and image quality score were statistically analyzed by comparing with contrast group .[Results]Statistical differences existed in ED at each BMI level between study and contrast groups .Statistical differences of CT value of AR and image background noise existed between groups A and A1 .Statistically significant differences of SNR existed among three BMI groups and no statistical difference for CNR of LM and psRCA .The evaluable rates were over 89% in low and moderate BMI groups .And there were no statistical differences .However ,statistically significant difference existed in evaluable rates between groups C and C1 (90 .44% vs 83 .87% ) .[Conclusion]Satisfactory coronary CTA image quality may be ac‐quired with low‐concentration CM and low tube voltage .And iodine dosage and ED are lowered .