Department of Radiology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China.
Clin Radiol. 2010 Oct;65(10):809-14. doi: 10.1016/j.crad.2010.05.005. Epub 2010 Jul 21.
To evaluate image quality and radiation dose for 128-detector prospective electrocardiogram (ECG)-gated computed tomography coronary angiography (CTCA) compared with a low-dose retrospective ECG-gated imaging protocol.
Thirty-one and 47 patients suspected of having coronary artery disease were enrolled into groups examined using prospective and low-dose retrospective ECG-gated CT protocols respectively. All examinations were performed on a 128-detector CT system (Definition AS, Siemens Healthcare, Forchheim, Germany). Prospective CTCA was performed using following parameters: tube voltage 100 kV; tube current 205 mAs; centre of acquisition window 70% of the RR interval. The tube current for low-dose retrospective ECG-gated CTCA was full dose during 40-70% of the RR interval and partial dose for the rest of RR interval. The pitch varied between 0.2 and 0.5 depending on heart rate and patient size. Image quality of coronary arteries was evaluated using a four-point grading scale. The signal-to-noise ratios (SNRs) of enhanced arteries and myocardium were also measured, corresponding contrast-to-noise ratios (CNRs) were calculated, and the radiation doses received were recorded.
There was a significant difference in the image quality scores between the retrospective and prospective gating protocols (Chi-square=15.331, p=0.009). There was no significant difference between the SNRs of the contrasted artery and myocardium in these two groups, but the CNRs were increased in the prospective group. The mean radiation dose of prospective gating group was 2.71+/-0.67 mSv (range, 1.67-3.59 mSv), which was significantly lower than that of the retrospective group (p<0.001).
Prospective CT angiography can achieve lower radiation dose than that of low-dose retrospective CT angiography, with preserved image quality.
评估 128 层前瞻性心电图（ECG）门控计算机断层冠状动脉成像（CTCA）与低剂量回顾性 ECG 门控成像方案的图像质量和辐射剂量。
分别将 31 例和 47 例疑似冠心病患者纳入前瞻性和低剂量回顾性 ECG 门控 CT 方案组。所有检查均在 128 层 CT 系统（西门子医疗，德国福希海姆的 Definition AS）上进行。前瞻性 CTCA 使用以下参数：管电压 100 kV；管电流 205 mAs；采集窗中心为 RR 间期的 70%。低剂量回顾性 ECG 门控 CTCA 的管电流在 RR 间期的 40-70%时为全剂量，其余 RR 间期为部分剂量。根据心率和患者体型，螺距在 0.2 到 0.5 之间变化。采用四点分级量表评估冠状动脉的图像质量。还测量了增强动脉和心肌的信噪比（SNR），计算了相应的对比噪声比（CNR），并记录了所接受的辐射剂量。
回顾性和前瞻性门控方案的图像质量评分存在显著差异（卡方=15.331，p=0.009）。两组对比动脉和心肌的 SNR 无显著差异，但前瞻性组的 CNR 增加。前瞻性门控组的平均辐射剂量为 2.71+/-0.67 mSv（范围 1.67-3.59 mSv），明显低于回顾性组（p<0.001）。
前瞻性 CT 血管造影可实现比低剂量回顾性 CT 血管造影更低的辐射剂量，同时保持图像质量。
