初步探讨不同扫描触发阈值技术在CT冠状动脉成像中的应用价值

The Value of Different Scanning Trigger Threshold Technique in CT Imaging of Coronary Artery

目的探讨在256层CT冠状动脉造影中不同扫描触发阈值对图像质量的影响。方法根据不同扫描激发阈值,将接受256层CT冠状动脉造影检查的103例患者随机分为四组。第1组27例,触发阈值为120 HU;第2组26例,触发阈值为100 HU;第3组26例,触发阈值为80 HU;第4组24例,触发阈值为60 HU。同时选择右冠状动脉中段、左冠状动脉前降支中段及左回旋支远段测量对比剂增强水平。统计分析四组的图像质量和冠状动脉对比剂增强水平及从对比剂注射到触发扫描前所用延迟时间。结果不同触发扫描阈值所得冠状动脉造影图像,四组条件下的图像质量评分分别为(4.62±0.26)分,(4.65±0.27)分,(4.67±0.26)分,(3.40±0.02)分,前三组两两比较差异无统计学意义(P>0.05),第4组与其他三组两两比较差异有统计学意义(P<0.05)。右冠状动脉中段、左冠状动脉前降支中段及左回旋支远段平均CT值比较,前三组比较差异无统计学意义(P>0.05),第4组与其他三组比较差异有统计学意义(P<0.05)。四组患者从对比剂注射到触发扫描前所用延迟时间,两两组间比较差异有统计学意义(P<0.05)。结论在256层CT冠状动脉造影中确保图像质量的情况下,采取80 HU监测触发阈值时,能缩短扫描延迟时间,可以达到在保证图像质量的前提下有效减少对比剂用量。

Objective To study the the effect of different threshold preset value in image quality of 256 slice spiral CT coronary angiography. Methods 103 patients who underwent CT coronary angiography were randomly divided into 4 groups. In group one,there were 27 cases, the threshold preset value was set at 120HU. In group two, there were 26 cases, the threshold preset value was set at 100HU. In group three, there were 26 eases, the threshold preset value was set at 80HU. In group four, there were 24 cases,the threshold preset value was set at 60HU. The mean cardiac artery enhancement was measured. Image quality score, enhancement of milddle segment of the right coronary artery middle segment, Left anterior descending middle and Left circumflex distalof left coronary artery were analyzed and compared. Results The mean image quality scores of 4 groups were 4.62±0.26, 4.65±0.27, 4.67±0.26, 3.40±0.02, respectively. There was no statistically difference （ P 〉 0.05 ） in the previous three groups ; there were significant difference between group 4 and other three groups. The enhancement of the 4 groups of the right coronary artery middle segment, Left anterior descending middle and Left circumflex distal were： group 1, RCAm 400. （ 14±78.08 ） HU, LADm （ 382.26±65.34 ） HU, LCXd （337.73±47.94）HU;group 2,RCAm （358.21±115.30） HU,LADm （352.46±92.39） HU,LCXd （333.37±79.18） HU ; group 3, RCAm （ 354.54±86.68 ） HU, LADm （ 351.14±82.07 ） HU, LCXd （ 330.50±73.18 ） HU ; group 4, RCAm （ 261.56±32.11 ） HU, LADm （ 260.52±42.64 ） HU, LCXd （ 229.32±45.77 ） HU. There was no statistically difference （ P 〉 0.05 ） in the previous three groups, there were significant difference between group 4 and the other three groups. The mean time from contrast injection to the scanning of 4 groups were ： groupl, （ 15.25±4.11 ） s ; group 2, （ 13.65 ±2.06 ） s ; group 3, （ 12.00±1.32 ） s ; group 4, （ 10.22±2.39 ） s, there were statistical difference between 4 groups （ P 〈 0.05 ）.Conclusion The threshold preset value 80HU group can cut down the trigger delay time,reduce contrast material injection dose, provide satisfactory quality at the same time.