Nakaura Takeshi, Awai Kazuo, Yauaga Yumi, Nakayama Yoshiharu, Oda Seitaro, Hatemura Masahiro, Nagayoshi Yasuhiro, Ogawa Hisao, Yamashita Yasuyuki
Department of Diagnostic Radiology, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Kumamoto, Japan.
Invest Radiol. 2008 Jul;43(7):512-9. doi: 10.1097/RLI.0b013e3181727505.
To compare patient-weight-adjusted and fixed iodine-dose protocols at coronary computed tomography angiography (CTA) using a 64-detector scanner and computer-assisted bolus tracking.
Approval from our institutional review board and patient prior informed consent were obtained before entering 60 patients with suspected coronary disease in this study. The patients were randomly assigned to one of 2 protocols. In the fixed iodine-dose protocol, they received a fixed dose of 80 mL Iopamidol-370; the injection duration was 20 seconds. In the weight-adjusted iodine-dose protocol, the dose was tailored to the patient body weight; this group received 1.0 mL/kg and the injection duration was shorter, ie, 15 seconds. Imaging was on a 64-detector CT scanner using a computer-assisted bolus tracking technique. A radiologist blinded to the protocol used measured the Hounsfield density number of the large vessels and coronary arteries. CT attenuation in the aortic root was compared in patients whose weight was less than 58 kg (group 1) or 58 kg or more (group 2). The standard deviation (SD) of CT attenuation in the aortic root and the myocardium was compared with evaluate image noise. Using a 3-point scale, 2 radiologists independently evaluated beam-hardening artifacts and coronary enhancement. Statistical analysis was with the two-tailed Student t test and the Mann-Whitney U test.
There was no significant difference between the protocols with respect to CT attenuation of the ascending aorta and coronary arteries. Under the fixed-iodine-dose protocol, mean CT attenuation in the aortic root was 421.3 +/- 51.5 Hounsfield unit (HU) in the lighter-, and 397.2 +/- 42.3 HU in the heavier weight group, respectively; the difference was statistically significant (P = 0.03). Under the weight-adjusted iodine-dose protocol, these values were 407.6 +/- 85.1 and 409.2 +/- 47.9 HU, respectively and the difference was not statistically significant (P = 0.17). The SD of the ascending aorta and myocardium was significantly higher for the fixed- than the weight-adjusted iodine-dose protocol. The mean visual score for beam-hardening artifacts was significantly lower in the weight-adjusted- than the fixed-iodine-dose protocol (P < 0.01), however, there was no significant difference in the enhancement of the coronary arteries (P = 0.82).
At 64-detector CTA of the heart, the patient weight-tailored dose protocol with the 15-second injection duration yielded significantly better image quality than the fixed-dose, 20-second injection duration protocol.
使用64排探测器扫描仪和计算机辅助团注追踪技术，比较冠状动脉计算机断层扫描血管造影（CTA）中患者体重校正碘剂方案和固定碘剂方案。
在本研究纳入60例疑似冠心病患者之前，获得了我们机构审查委员会的批准和患者的事先知情同意。患者被随机分配到两种方案之一。在固定碘剂方案中，他们接受80 mL碘帕醇-370的固定剂量；注射持续时间为20秒。在体重校正碘剂方案中，剂量根据患者体重调整；该组接受1.0 mL/kg，注射持续时间较短，即15秒。使用计算机辅助团注追踪技术在64排CT扫描仪上进行成像。一位对所使用方案不知情的放射科医生测量大血管和冠状动脉的亨氏密度值。比较体重小于58 kg（第1组）或58 kg及以上（第2组）患者主动脉根部的CT衰减。比较主动脉根部和心肌CT衰减的标准差（SD）以评估图像噪声。两位放射科医生使用3分制独立评估线束硬化伪影和冠状动脉强化情况。采用双尾Student t检验和Mann-Whitney U检验进行统计分析。
在升主动脉和冠状动脉的CT衰减方面，两种方案之间无显著差异。在固定碘剂方案下，体重较轻组主动脉根部的平均CT衰减为421.3±51.5亨氏单位（HU），体重较重组为397.2±42.3 HU；差异具有统计学意义（P = 0.03）。在体重校正碘剂方案下，这些值分别为407.6±85.1和409.2±47.9 HU，差异无统计学意义（P = 0.17）。固定碘剂方案的升主动脉和心肌的SD显著高于体重校正碘剂方案。体重校正碘剂方案中线束硬化伪影的平均视觉评分为显著低于固定碘剂方案（P < 0.01），然而，冠状动脉强化方面无显著差异（P = 0.82）。
在心脏64排CTA检查中，注射持续时间为15秒的患者体重调整剂量方案比固定剂量、注射持续时间为20秒的方案产生的图像质量显著更好。
