SGER: Dynamics of Encapsulated Microbubbles for Medical Ultrasound

摘要CTS-0352829K。DelawareSarkar大学将微泡静脉注入患者体内，以增强超声图像的对比度。我们的目的是为这些微泡造影剂建立一个可靠的数学模型，并用它来表征不同的造影剂。具体地说，建模的重点是保护由脂质、蛋白质或表面活性剂制成的造影剂微泡。尽管游离微泡(无胶囊)在反射超声波和增强图像对比度方面表现得更好，但它们在几秒钟内就能在血流中溶解。这种封装稳定了它们，使对比度成像成为可能。技术优点：将开发一种新的界面模型，用于具有表面流变性的包覆。这些特性将通过临床批准的造影剂Definity和Optison的体外衰减实验来确定。我们认为，所提出的吸收界面模型包含了基本的物理原理，并且在更宽的频率和幅度范围内仍然有效。我们将通过将模型预测与散射实验(不同于用于模型确定的实验)进行比较来检验这一假设。模型参数将使用适合于使用较低能量的脉冲进行实验的模型的线性化版本来确定。然而，所开发的模型的非线性动力学将与实测的谐波和亚谐辐射进行比较。我们用Optison文献中提供的实验数据进行的初步模拟显示，与测量的亚谐辐射符合得很好。我们正在与托马斯·杰斐逊医学院和医院放射科医学博士Flemming Forsberg和Barry Goldberg教授合作，将我们的研究应用于临床。除了超声造影剂之外，这项拟议的研究还将提供对胶体和悬浮液中界面动力学的重要理解。更广泛的影响：超声波检查是最安全和最受欢迎的成像手段(世界上每三项成像研究中就有一项是超声波测试)。然而，由于对比度差，超声图像的使用受到限制。例如，2000年在美国进行的1700万次超声心动图检查中，有20%是不理想的，即不能提供对冠心病的明确诊断。良好的造影剂将使异常血流的可靠成像成为可能，从而导致早期可靠的诊断。造影剂的使用不仅限于心脏，还包括肾脏、肝脏和大脑的成像。开发有效的造影剂和有效的模式只能通过体外研究和临床合作来实现，就像这里所建议的那样。拟议的特征将用于向代理开发商(如amersham Health、百时美施贵宝)和扫描仪制造商(如GE)提供有用的指导方针。这项研究将包括工程学研究生和本科生，他们学习的是一门非传统的跨学科医学成像科学。

AbstractCTS-0352829K. Sarkar, University of DelawareMicrobubbles are intravenously introduced into a patient's body to enhance the contrast of an ultrasound image. Our aim is to develop a reliable mathematical model for these microbubble contrast agents and characterize different agents with it. Specifically the focus of the modeling is the protective encapsulation of a contrast microbubble made of lipids, proteins or surfactants. Even though free microbubbles (without encapsulation) perform much better in reflecting ultrasound and enhancing image contrast, they issolve in blood stream in few seconds. The encapsulation stabilizes them making contrast imaging possible. Technical merit: A new interface model for the encapsulation with surface rheological properties will be developed. These properties will be determined by in vitro attenuation experiments with clinically approved contrast agents Definity and Optison. We claim that the proposed model of absorbed interface contains the essential physics, and will remain valid over a wider range of frequency and amplitude. We will test this hypothesis by comparing model predictions with scattering experiments (different from those used for model determination). The model parameters will be determined using a linearized version of the model appropriate for experiments with pulses of less energy. However, the developed models nonlinear dynamics will be compared with measured harmonic and subharmonic emissions. Our preliminary modeling with experimental data available in the literature for Optison shows encouraging agreement with measured subharmonic emission. We are collaborating on the clinical implementation of our research with Professors Flemming Forsberg and Barry Goldberg, MD of the Radiology Department at Thomas Jefferson Medical College and Hospital. Beyond contrast ultrasound the proposed research will provide critical understanding of interface dynamics in colloids and suspensions. Broader Impact: Ultrasound examination is the safest and the most popular means of imaging (one in every three imaging studies performed in the world is an ultrasound test). Utility of ultrasonography images however is limited due to poor contrast. For instance, 20 percent of the 17 million echocardiography performed in the United States in 2000 were suboptimal, i.e. did not provide definitive diagnosis for coronary heart disease. A good contrast agent will enable reliable imaging of abnormal blood flows leading to early reliable diagnosis. Use of contrast agent is not limited to heart; it also includes imaging kidney, liver and brain. Development of effective contrast agents and efficient modality can only be achieved through in vitro research with clinical collaboration such as proposed here. The proposed characterization will be used to provide useful guidelines to agent developers (e.g. Amersham Health, Bristol Myers Squibb) and scanner manufacturers (e.g. GE). The research will involve engineering graduate and undergraduate students in a non-traditional cross-disciplinary science of medical imaging.