Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Chapel Hill, NC 27599, USA.
Contrast Media Mol Imaging. 2011 May-Jun;6(3):126-31. doi: 10.1002/cmmi.414. Epub 2011 Jan 19.
Microbubble contrast agents are currently implemented in a variety of both clinical and preclinical ultrasound imaging studies. The therapeutic and diagnostic capabilities of these contrast agents are limited by their short in-vivo lifetimes, and research to lengthen their circulation times is on going. In this manuscript, observations are presented from a controlled experiment performed to evaluate differences in circulation times for lipid shelled perfluorocarbon-filled contrast agents circulating within rodents as a function of inhaled anesthesia carrier gas.
The effects of two common anesthesia carrier gas selections - pure oxygen and medical air were observed within five rats. Contrast agent persistence within the kidney was measured and compared for oxygen and air anesthesia carrier gas for six bolus contrast injections in each animal. Simulations were performed to examine microbubble behavior with changes in external environment gases.
A statistically significant extension of contrast circulation time was observed for animals breathing medical air compared to breathing pure oxygen. Simulations support experimental observations and indicate that enhanced contrast persistence may be explained by reduced ventilation/perfusion mismatch and classical diffusion, in which nitrogen plays a key role by contributing to the volume and diluting other gas species in the microbubble gas core.
Using medical air in place of oxygen as the carrier gas for isoflurane anesthesia can increase the circulation lifetime of ultrasound microbubble contrast agents.
微泡对比剂目前在各种临床和临床前超声成像研究中得到应用。这些对比剂的治疗和诊断能力受到其体内寿命短的限制，目前正在进行延长其循环时间的研究。本文介绍了一项对照实验的观察结果，该实验旨在评估作为啮齿动物吸入麻醉载体气体的函数，脂质壳氟碳填充对比剂的循环时间差异。
在五只大鼠中观察了两种常见麻醉载体气体选择（纯氧和医用空气）的影响。对六次每个动物的单次对比剂注射中氧气和空气麻醉载体气体的肾脏内对比剂持续时间进行了测量和比较。模拟了外部环境气体变化对微泡行为的影响。
与呼吸纯氧相比，呼吸医用空气的动物观察到对比循环时间显著延长。模拟结果支持实验观察结果，并表明增强的对比剂持续时间可能可以通过减少通气/灌注不匹配和经典扩散来解释，其中氮通过对微泡气体核心中的体积和稀释其他气体种类起到关键作用来发挥作用。
在异氟醚麻醉中使用医用空气代替氧气作为载体气体，可以增加超声微泡对比剂的循环寿命。
