Department of Radiology, Cardiovascular Imaging Section, Northwestern University, 737 N. Michigan Ave. Ste 1600, Chicago, IL, 60611, USA.
Int J Cardiovasc Imaging. 2011 Oct;27(7):1025-34. doi: 10.1007/s10554-010-9742-9. Epub 2010 Nov 3.
The purpose of this study was to investigate the effects of a prospective ECG-gated, low kilovoltage and low mAs protocol on image quality and radiation dose when acquiring CT angiography of the thoracic aorta (CTTA). Sixty patients with a body mass index (BMI) of less than 30 and a heart rate of less than 100 beats per minute (bpm) were included in the study. Thirty consecutive patients were examined with retrospective ECG-gating and standard parameters (group A) (120 kVp, 340 reference effective mAs).The next thirty (group B) were examined with prospective ECG-gating, 100 kVp and 170 mAs. Quantitative analysis included measurements of image resolution of the thoracic aorta at three levels, mean attenuation in the aorta and signal to noise ratio (SNR). Qualitative analysis assessed image artifact and graded image quality on five point scales. Effective radiation doses were estimated. The radiation dose of group A was 26.2 ± 6.0 mSv (mean ± standard deviation). For group B it was 2.9 ± 0.5 mSv (P < 0.001). Mean aortic attenuation was significantly higher in group B than group A (487 ± 100 Hu and 372 ± 74 Hu) (P < 0.01).SNR was significantly higher in group A (21.7 ± 5.7 compared to 14.5 ± 5.3) (P < 0.01). Image resolution was significantly higher in group B at all measured anatomical levels (P < 0.01). There was no significant difference in the final subjective scores between group A and group B (Mann-Whitney U = 438, P = 0.79). High quality low dose CTTA is clinically achievable, in patients with a BMI less than 30 and a heart rate less than 100 bpm, using a prospective ECG-gated, low kilovoltage, low mAs technique.
本研究旨在探讨前瞻性 ECG 门控、低千伏和低毫安技术在进行胸部 CT 血管造影（CTTA）时对图像质量和辐射剂量的影响。本研究纳入了 60 名 BMI 小于 30 且心率小于 100 次/分钟的患者。连续 30 名患者采用回顾性 ECG 门控和标准参数（A 组）（120 kVp，340 参考有效毫安）进行检查。接下来的 30 名患者（B 组）采用前瞻性 ECG 门控、100 kVp 和 170 mAs 进行检查。定量分析包括测量三个层面的胸主动脉图像分辨率、主动脉平均衰减和信噪比（SNR）。定性分析采用五分制评估图像伪影和图像质量评分。估计有效辐射剂量。A 组的辐射剂量为 26.2 ± 6.0 mSv（平均值 ± 标准差）。B 组的辐射剂量为 2.9 ± 0.5 mSv（P < 0.001）。B 组的主动脉平均衰减明显高于 A 组（487 ± 100 Hu 和 372 ± 74 Hu）（P < 0.01）。A 组的 SNR 明显高于 B 组（21.7 ± 5.7 比 14.5 ± 5.3）（P < 0.01）。B 组在所有测量的解剖层面的图像分辨率均明显高于 A 组（P < 0.01）。A 组和 B 组的最终主观评分无显著差异（Mann-Whitney U = 438，P = 0.79）。在 BMI 小于 30 且心率小于 100 次/分钟的患者中，采用前瞻性 ECG 门控、低千伏、低毫安技术可实现高质量低剂量 CTTA。
