超低剂量心脏CT扫描对冠状动脉狭窄分级和量化的价值

Value of Ultra-low Dose Coronary CT Angiography for Classification and Quantification of Coronary Stenosis

目的:在冠状动脉CT成像(CCTA)中,以100 kV扫描为参照,评估70 kV扫描对冠状动脉狭窄程度分级和量化的一致性。方法:选取70名临床怀疑或已知冠心病且适合行CCTA检查的患者,使用256排宽探测器CT,分别用70 kV和100kV管电压进行单心动周期CCTA检查。比较两组扫描的有效辐射剂量(ED)及图像信噪比(SNR)。对冠状动脉的9个节段进行狭窄程度分析。将狭窄程度分为正常(0%)、轻度(1%～49%)、中度(50%～69%)和重度(70%～100%)四个等级。记录狭窄程度一致的冠状动脉节段数目。使用Bland-Altman分析比较冠脉狭窄程度的一致性。结果:70 kV扫描的有效辐射剂量显著低于100 kV扫描的,分别为(0.26±0.08)mSv和(1.07±0.05)mSv(P <0.01),信噪比显著低于100 kV扫描,分别为16.53±5.87和18.19±6.07(P <0.05)。在630个冠状动脉节段中,608个(96.5%)分级一致。Bland-Altman分析显示两组扫描方法评估狭窄程度差异性的95%可信区间约在15%～30%之间。结论:70kV冠状动脉CTA成像可以大幅度降低辐射剂量,对冠脉狭窄程度的分级与常规100kV扫描基本一致。但是对冠状动脉的精确量化测量与常规扫描有一定的差异性。

Objective: To investigate the agreement between 70 k V and 100 k V scan for classification and quantification of coronary artery stenosis, on wide-detector coronary computed tomography angiography(CCTA)examination. Methods: 70 patients of suspected or known coronary artery disease were included, who were suitable for CCTA. Single heartbeat CCTA was performed on 256-row wide-detector CT by using 70 k V and100 k V tube voltage, respectively. Effective radiation dose and signal-to-noise ratio(SNR) were compared between these two groups. Nine coronary segments were evaluated, in which the stenosis degree was categorized as: normal(0%), mild(1% ~ 49%), moderate(50% ~69%) and severe(70% ~ 100%). We recorded the number of consistent stenosis category between 70 k V and 100 k V scan. Bland-Altman analysis was used to evaluate coronary stenosis between 70 k V and 100 k V scan. Result: Effective radiation dose of 70 k V scan was significantly lower than that of 100 k V, which were(0.26 ± 0.08)mSv and(1.07 ± 0.05)mSv(P < 0.01),respectively. SNR of 70 k V scan was significantly lower either, which were 16.53 ± 5.87 and 18.19 ± 6.07(P < 0.05), respectively. Stenosis degree of 630 coronary segments were evaluated, in which 608(96.5%) were consistent between 70 k V and 100 k V scan. Bland-Altman analysis revealed a 95% confidence interval(CI)between 15% and 30% for coronary stenosis between the two groups. Conclusion: CCTA of 70 k V tube voltage significantly reduces radiation dose, while showing optimal consistent categorization for coronary stenosis to100 k V scan. However, variability exists between 70 k V and 100 k V scans for precise quantification of coronary stenosis.