University of Leipzig-Heart Center, Department of Diagnostic and Interventional Radiology, Strümpellstrasse 39, D-04289, Leipzig, Germany.
Eur J Radiol. 2012 Sep;81(9):2221-30. doi: 10.1016/j.ejrad.2011.09.019. Epub 2011 Oct 22.
To evaluate the influence of different heart rates and arrhythmias on scanner performance, image acquisition and applied radiation exposure in prospectively ECG triggered computed tomography (pCT).
An ECG simulator (EKG Phantom 320, Müller & Sebastiani Elektronik GmbH, Munich, Germany) was used to generate different heart rhythms and arrhythmias: sinus rhythm (SR) at 45, 60, 75, 90 and 120/min, supraventricular arrhythmias (e.g. sinus arrhythmia, atrial fibrillation) and ventricular arrhythmias (e.g. ventricular extrasystoles), pacemaker-ECGs, ST-changes and technical artifacts. The analysis of the image acquisition process was performed on a 64-row multidetector CT (Brilliance, Philips Medical Systems, Cleveland, USA). A prospectively triggered scan protocol as used for routine was applied (120 kV; 150 mAs; 0.4s rotation and exposure time per scan; image acquisition predominantly in end-diastole at 75% R-R-interval, in arrythmias with a mean heart rate above 80/min in systole at 45% of the R-R-interval; FOV 25 cm). The mean dose length product (DLP) and its percentage increase from baseline (SR at 60/min) were determined.
Radiation exposure can increase significantly when the heart rhythm deviates from sinus rhythm. ECG-changes leading to a significant DLP increase (p<0.05) were bifocal pacemaker (61%), pacemaker dysfunction (22%), SVES (20%), ventricular salvo (20%), and atrial fibrillation (14%). Significantly (p<0.05) prolonged scan time (>8 s) could be observed in bifocal pacemaker (12.8 s), pacemaker dysfunction (10.7 s), atrial fibrillation (10.3 s) and sinus arrhythmia (9.3 s).
In prospectively ECG triggered CT, heart rate and rhythm can provoke different types of scanner performance, which can significantly alter radiation exposure and scan time. These results might have an important implication for indication, informed consent and contrast agent injection protocols.
评估不同心率和心律失常对前瞻性心电图触发计算机断层扫描（pCT）中扫描仪性能、图像采集和应用辐射暴露的影响。
使用心电图模拟器（EKG Phantom 320，Müller & Sebastiani Elektronik GmbH，慕尼黑，德国）生成不同的心率和心律失常：窦性心律（SR）45、60、75、90 和 120 次/分钟、室上性心律失常（如窦性心律失常、心房颤动）和室性心律失常（如室性期外收缩）、起搏器心电图、ST 段改变和技术伪影。使用 64 排多层 CT（Brilliance，飞利浦医疗系统，克利夫兰，美国）对图像采集过程进行分析。应用常规前瞻性触发扫描方案（120 kV；150 mAs；0.4s 旋转和曝光时间/扫描；图像采集主要在舒张末期 75%的 R-R 间期，在平均心率高于 80 次/分钟的心律失常中在收缩期 45%的 R-R 间期；视野 25 cm）。确定平均剂量长度乘积（DLP）及其相对于基线（SR 60 次/分钟）的百分比增加。
当心率偏离窦性心律时，辐射暴露会显著增加。导致 DLP 显著增加的心电图变化（p<0.05）为双焦点起搏器（61%）、起搏器功能障碍（22%）、SVES（20%）、心室速发（20%）和心房颤动（14%）。可以观察到双焦点起搏器（12.8 秒）、起搏器功能障碍（10.7 秒）、心房颤动（10.3 秒）和窦性心律失常（9.3 秒）扫描时间显著延长（>8 秒）（p<0.05）。
在前瞻性心电图触发 CT 中，心率和节律可引起不同类型的扫描仪性能变化，从而显著改变辐射暴露和扫描时间。这些结果可能对适应证、知情同意和造影剂注射方案具有重要意义。
