Klinik für Herz und Kreislauferkrankungen, Deutsches Herzzentrum Munchen, Munich, Bavaria 80636, Germany.
AJR Am J Roentgenol. 2010 Jun;194(6):1495-9. doi: 10.2214/AJR.09.3543.
Concerns have been raised about the radiation exposure of coronary CT angiography (CTA). Recently, a prospective ECG-triggered sequential coronary CTA technique was developed to reduce exposure to ionizing radiation. The purpose of this analysis was to determine the impact of a sequential scanning technique on image quality and radiation dose in a prespecified subgroup analysis of the Prospective Multicenter Study on Radiation Dose Estimates of Cardiac CT Angiography I (PROTECTION I) Study when compared with a standard helical scanning technique.
This analysis comprises 685 64-MDCT coronary angiography studies of 47 international study sites in which the image quality was assessed by an experienced coronary CTA investigator using a 4-point score (1 = nondiagnostic, 4 = excellent image quality). Image quality was analyzed in all patients studied with the sequential scanning mode (n = 99) and in randomly selected patients of the population studied with the helical acquisition mode (n = 586). Radiation dose estimates were derived from the dose-length product (DLP) and a conversion coefficient for the chest (0.014 mSv x mGy(-1) x cm(-1)).
Although the sequential scanning mode significantly reduced radiation dose estimates by 68% from 11.2 mSv for the helical mode to 3.6 mSv for the sequential mode (p < 0.001), the median diagnostic image quality scores were comparable in both groups. The median diagnostic score for both scanning modes was 3.5 (interquartile range: sequential vs helical mode, 3.25-3.75 vs 3.0-3.75, respectively; p = 0.62).
The results of the PROTECTION I Study suggest that the prospective ECG-triggered sequential coronary CTA technique significantly reduces radiation dose without impairing image quality when compared with the standard retrospective helical data acquisition in patients with a low and stable heart rate.
冠状动脉 CT 血管造影（CTA）的辐射暴露问题引起了关注。最近，开发了一种前瞻性心电图触发连续冠状动脉 CTA 技术，以减少电离辐射的暴露。本分析的目的是在 Prospective Multicenter Study on Radiation Dose Estimates of Cardiac CT Angiography I（PROTECTION I）研究的预设亚组分析中，与标准螺旋扫描技术相比，确定连续扫描技术对图像质量和辐射剂量的影响。
本分析包括来自 47 个国际研究中心的 685 例 64 层 MDCT 冠状动脉造影研究，由有经验的冠状动脉 CTA 研究者使用 4 分制评分（1 = 无法诊断，4 = 图像质量极佳）评估图像质量。对所有使用连续扫描模式进行研究的患者（n = 99）和在使用螺旋采集模式随机选择的患者（n = 586）进行图像质量分析。剂量长度乘积（DLP）和胸部转换系数（0.014 mSv x mGy(-1) x cm(-1)）用于推导辐射剂量估计值。
尽管连续扫描模式使辐射剂量估计值显著降低了 68%，从螺旋模式的 11.2 mSv 降至连续模式的 3.6 mSv（p < 0.001），但两种扫描模式的中位数诊断图像质量评分相当。两种扫描模式的中位数诊断评分均为 3.5（四分位间距：连续 vs 螺旋模式，3.25-3.75 vs 3.0-3.75，分别；p = 0.62）。
PROTECTION I 研究的结果表明，与标准回顾性螺旋数据采集相比，前瞻性心电图触发连续冠状动脉 CTA 技术在心率低且稳定的患者中显著降低了辐射剂量，而不会降低图像质量。
