New Non-invasive IMAGING methods for biomedical applications

在过去的一年里，这个项目在两个主要领域发挥了作用，新的成像技术和人类心脏的磁共振成像。新的成像技术包括霍尔效应成像和电声成像。两者都揭示了组织的电学性质，如离子和大分子的流动性。霍尔效应3D断层成像已经在幻影和猪主动脉样本中得到了演示。在这些实验和理论分析的基础上，探索了定量测量复杂生物样品介电常数的可能性。结果表明，尽管HEI提供了具有介电对比度的高分辨率图像，但它比定量测量基本电常数更适合定性表征。在心脏核磁共振领域，我们的团队开发了一种快速而健壮的相位标记运动跟踪技术。它是基于早期的刺激回声方法。然而，读数和伪影抑制方面的改进将该方法带入了临床环境的实际使用领域。它能够在14次心跳中绘制2D应变图，并几乎实时地直接在扫描仪控制台上显示应变图。它现在用于在马里兰州贝塞斯达的苏尔伯班医院通过急诊室入院的患者。在优化临床应用的同时，这项技术也是研究心脏生物力学中尚未回答的问题的非常有用的工具，这项研究正在进行中。心脏核磁共振的另一个研究领域是多种造影剂，特别是与回声超声检查有关的造影剂。

This project has worked in two general areas over the last year, new imaging techniques and MR imaging of the human heart. New imaging techniques include Hall effect imaging and electroaoucstic imaging. Both reveal information about the electrical properties of tissue, such as ion and macromolecule mobility. Hall effect 3D tomography has been demonstrated in phantoms and porcine aorta samples. Based on these experiments and theoretical analysis, the potential for quantitative measurements of the dielectric constants in complex biological samples was explored. It was concluded that while HEI provides high resolution images with dielectric based contrast, it is more suited for qualitative characterization than quantitative measurements of the basic electrical constants. In the area of cardiac MRI, our group developed a phase- labeled motion tracking technique that is fast and robust. It is based on earlier stimulated echo methods. However improvements in readout and artifact suppression brought this method into the realm of practical use in clinical settings. It is capable of 2D strain mapping in 14 heartbeats, and displays the strain maps directly on the scanner console in near real time. It is now used on patients admitted through ER at Surburban Hospital, Bethesda, MD. Parallel to optimization for clinical application, this technique is also a very useful tool in studying the unanswered questions in the biomechanics of the heart, and this research is underway. Another area of research in cardiac MRI has been versatile contrast agents, particularly in relation to echo-sonography.