等中心扫描降低多层螺旋CT冠状动脉血管成像辐射剂量的随机对照研究

A randomized controlled study on isocenter scanning in reducing the radiation dose of multi-slice spiral CT coronary angiography

目的探讨等中心扫描对降低冠状动脉多层螺旋CT血管成像(MSCTA)辐射剂量的价值。方法采用前瞻性随机对照研究方法。纳入广东省中医院珠海医院2016年11月—2018年4月144例行冠状动脉MSCTA检查患者,将患者按随机区组法分为A、B、C、D 4组,每组36例。A组采用常规扫描定位,电流为智能毫安;B、C、D组采用等中心位置扫描,电流分别为智能毫安、智能毫安的90%、智能毫安的80%。4组扫描管电压均为120 kV。比较4组患者冠状动脉MSCTA图像的客观图像质量噪声、信噪比(SNR),主观质量评分比及辐射剂量(ED),对直径>1.5 mm的血管节段采用冠状动脉15分段法评分,用以评价主观图像质量。客观噪声方面,4组重建图像中的主支气管选择,感兴趣区(面积约15.0 mm^2),测量其标准差值作为噪声值,SNR为其CT值/标准差。结果MSCTA图像分析显示,以D、A、C、B组为序,噪声依次降低(分别为15.09±2.97、2.68±2.47、2.57±2.29和2.45±4.36),SNR依次升高(分别为63.74±19.78、78.64±14.66、78.66±14.84和79.66±22.90);D组与A、B、C组两两比较,噪声高而SNR低,差异均有统计学意义(P值均<0.05);A、B、C组间噪声及SNR两两比较,差异均无统计学意义(P值均>0.05)。4组冠状动脉图像质量主观评分优良率98.9%(1 939/1 960),4组间比较差异均无统计学意义(P值均>0.05);A、B、C、D辐射剂量依次降低,分别为(3.39±1.39)mSv、(2.89±1.21)mSv、(2.56±1.05)mSv,(2.14±0.87)mSv,其中A组明显高于C、D组,B组高于D组,差异均有统计学意义(P值均<0.05)。结论在不降低冠状动脉成像质量的情况下,等中心扫描能降低冠状动脉MSCTA的辐射剂量。

Objective To investigate the value of isocenter scanning in reducing radiation dose in coronary artery multi-slice spiral CT angiography (MSCTA). Methods This is a prospective randomized controlled trial. A total of 144 patients with coronary artery MSCTA were collected in Guangdong Hospital of Traditional Chinese Medicine, Zhuhai Hospital from November 2016 to April 2018. They were randomly divided into groups A, B, C, and D, with 36 patients in each group. Group A was in conventional body position, and the current was intelligent milliampere;Groups B, C, D were in the isocenter body position, and the current was intelligent milliampere, 90% of intelligent milliampere, 80% of intelligent milliampere, respectively. The tube voltage of each group was 120 kV. The image quality noise, sigal noise ratio (SNR), subjective evaluation of image quality and radiation dose (ED) of images were compared among the four groups. The subjective image quality (the vascular diameter>1.5 mm) were evaluated by 15 sections method.The four sets of reconstructed images chosen from gas of primary bronchi which covers an area of about 15.0 mm2 was measured as noise value and SNR was its CT/standard deviation. Results Among the four groups, there was a statistically significant difference in the noise and SNR between group D with group A, B, C(all P values<0.05). There was no significant difference in noise and signal-to-noise ratio between groups A, B and C(all P values>0.05). The noise gradually decreased while the SNR gradually increased in the order of group D, A, C, and B(15.09±2.97, 2.68±2.47, 2.57±2.29, 2.45±4.36 and 63.74±19.78, 78.64±14.66, 78.66±14.84, 79.66±22.90). There was no statistically significant difference in the subjective scores of coronary arteries among the four groups(all P values>0.05). The subjective scores of coronary artery image quality were excellent in all 4 groups, and the good total rate was 98.9%(1 939/1 960). Radiation doses of A, B, C, and D group were (3.39±1.39) mSv,(2.89±1.21) mSv,(2.56±1.05) mSv, and (2.14±0.87) mSv, respectively.The radiation dose of group A was signficantly higher than group C and D(all P values<0.05). Conclusions An isocenter scan can reduce the radiation dose of coronary MSCTA without reducing the quality of coronary imaging.