Department of Radiology, An Zhen Hospital, Capital Medical University, An Zhen Li, Beijing 100029, China.
Eur J Radiol. 2012 Jul;81(7):1549-54. doi: 10.1016/j.ejrad.2011.02.032. Epub 2011 Mar 9.
To evaluate the feasibility of low dose target-CTA volume scan for left atrium and pulmonary veins imaging using 320-row CT.
Forty-two patients (females 12, males 30; mean age 55.2 years; mean body mass index (BMI) 25.7 kg/m(2)) with persistent or intermittent atrial fibrillation before catheter ablation were enrolled in this study. Scan protocol was target-CTA volume scan under prospective ECG-gating. The target of the exposure was only set at 40% of the R-R interval (which was at the left atrium maximal volume). The exposure time was minimal setting (350 ms). Tube voltage 100 kV (BMI ≤ 25 kg/m(2)) or 120 kV (BMI>25 kg/m(2)), tube current 350-420 mA, and field of view of 180 mm × 180 mm-200 mm × 200 mm were used. The scanning range was from the level of the tracheal bifurcation to the diaphragm, and enabled to cover the left atrium and central pulmonary veins (120-140 mm). All of patients were divided into two groups according kV setting (100 kV and 120 kV). The image quality (good, moderate and poor) was evaluated by two reviewers. The CT-attenuation, image noise and contrast to noise ratio (CNR) of left atrium and every pulmonary vein branch were evaluated, respectively. The effective dose (ED) was calculated using a conversion coefficient for the chest 0.017.
Of 42 patients, the image quality was good in 26 cases (62%) and moderate in 16 cases (38%). There was no statistical difference in the CT-attenuation and CNR of left atrium and central pulmonary veins between the two groups (P>0.05). The mean ED was 1.90 ± 0.19 mSv (range 1.57-2.25 mSv) in 100 kV group, and 3.83 ± 0.31 mSv (range 3.39-4.54 mSv) in 120 kV group.
The low dose target-CTA volume scan is feasible in pulmonary veins and left atrium imaging using 320-row CT. Slim patients can be scanned at 100 kV setting without loss of image quality.
评估使用 320 排 CT 进行低剂量靶区 CT 血管造影容积扫描左心房和肺静脉成像的可行性。
本研究纳入了 42 例（女性 12 例，男性 30 例；平均年龄 55.2 岁；平均体重指数（BMI）25.7kg/m2）在导管消融前持续性或间歇性心房颤动的患者。扫描方案为前瞻性心电图门控靶区 CT 血管造影容积扫描。曝光目标仅设置在 RR 间期的 40%（即左心房最大容积处）。曝光时间设置为最小（350ms）。管电压 100kV（BMI≤25kg/m2）或 120kV（BMI>25kg/m2）、管电流 350-420mA、视野 180mm×180mm-200mm×200mm 用于扫描。扫描范围从气管分叉处到膈肌，可覆盖左心房和中央肺静脉（120-140mm）。所有患者均根据管电压设置（100kV 和 120kV）分为两组。由两位阅片者评估图像质量（好、中、差）。分别评估左心房和每支肺静脉分支的 CT 衰减值、图像噪声和对比噪声比（CNR）。使用胸部 0.017 的转换系数计算有效剂量（ED）。
42 例患者中，26 例（62%）图像质量良好，16 例（38%）图像质量中等。两组间左心房和中央肺静脉的 CT 衰减值和 CNR 无统计学差异（P>0.05）。100kV 组的平均 ED 为 1.90±0.19mSv（范围 1.57-2.25mSv），120kV 组为 3.83±0.31mSv（范围 3.39-4.54mSv）。
使用 320 排 CT 进行肺静脉和左心房成像，低剂量靶区 CT 血管造影容积扫描是可行的。体型较瘦的患者可以在 100kV 管电压设置下进行扫描，而不会降低图像质量。
