University of Heidelberg, Department of Diagnostic and Interventional Radiology, Heidelberg, Germany.
Eur J Radiol. 2013 May;82(5):e232-9. doi: 10.1016/j.ejrad.2012.12.013. Epub 2013 Jan 14.
To investigate the value of 4 different protocols for prospectively triggered 256-slice coronary computed tomography angiography (coronary CTA).
Two hundred and ten patients underwent prospectively triggered coronary CTA for suspected or known coronary artery disease (CAD). Patients with heart rate >75 bps before the scan despite ß-blocker administration and with arrhythmia were excluded. From January to September 2010, 60 patients underwent coronary CTA using a non-tailored protocol (120 kV; 200 mAs) and served as our 'control' group. From September 2010 to April 2012, based on the body mass index (BMI) of the examined patients (BMI subgroups of <25; 25-28; 28-30, and ≥ 30 kg/m(2)) current tube voltage and tube current were: (1) slightly, (2) moderately or (3) strongly reduced, resulting into the 3 following BMI-adapted acquisition groups: (1) a 'standard' (100/120 kV; 100-200 mAs; n=50), 2) a 'low dose' (100/120 kV; 75-150 mAs; n=50), and 3) an 'ultra-low dose' (100/120 kV; 50-100 mAs; n=50) protocol.
Patients examined using the non-tailored protocol exhibited the highest radiation exposure (3.2 ± 0.4 mSv), followed by the standard (1.6 ± 0.7 mSv), low-dose (1.2 ± 0.6 mSv) and ultra-low dose protocol (0.7 ± 0.3 mSv) (radiation savings of 50%, 63% and 78% respectively). Overall image quality was similar with standard dose (1.9 ± 0.6) and low-dose (2.0 ± 0.5) compared to the non-tailored group (1.9 ± 0.5) (p=NS for all). In the ultra-low dose group however, image quality was significant reduced (2.7 ± 0.6), p<0.05 versus all other groups).
Using BMI-adapted low dose acquisitions image quality can be maintained with simultaneous radiation savings of ∼65% (dose of ∼1 mSv). This appears to be the lower limit for diagnostic coronary CTA, whereas ultra-low dose acquisitions result in significant image degradation.
探讨 4 种不同方案在前瞻性触发 256 层冠状动脉 CT 血管造影（冠状动脉 CTA）中的应用价值。
210 例疑似或已知冠心病（CAD）患者行前瞻性触发冠状动脉 CTA。扫描前心率>75 bps 且未服用β受体阻滞剂或存在心律失常的患者被排除。2010 年 1 月至 2010 年 9 月，60 例患者采用非定制方案（120 kV；200 mAs）进行冠状动脉 CTA，作为我们的“对照组”。2010 年 9 月至 2012 年 4 月，根据受检患者的体重指数（BMI）（BMI 亚组<25；25-28；28-30 和≥30 kg/m(2))，当前管电压和管电流分别为：（1）轻度，（2）中度或（3）重度降低，形成以下 3 种 BMI 适应采集组：（1）“标准”（100/120 kV；100-200 mAs；n=50），2）“低剂量”（100/120 kV；75-150 mAs；n=50）和 3）“超低剂量”（100/120 kV；50-100 mAs；n=50）方案。
非定制方案组患者的辐射暴露量最高（3.2±0.4 mSv），其次是标准方案组（1.6±0.7 mSv）、低剂量组（1.2±0.6 mSv）和超低剂量组（0.7±0.3 mSv）（分别降低 50%、63%和 78%）。总体图像质量与标准剂量（1.9±0.6）和低剂量（2.0±0.5）相似，而非定制组（1.9±0.5）（所有组间比较 p=NS）。然而，在超低剂量组，图像质量明显降低（2.7±0.6），与所有其他组比较，p<0.05。
使用 BMI 适应性低剂量采集，可以在保持图像质量的同时，将辐射量降低约 65%（剂量约为 1 mSv）。这似乎是诊断性冠状动脉 CTA 的下限，而超低剂量采集则会导致图像质量显著下降。
