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开展工作，新的成像技术和人类心脏的MR成像。新的成像技术包括霍尔效应成像和电声成像。两者都揭示了组织电学性质的信息，如离子和大分子的迁移性。霍尔效应三维断层扫描已被证明在幻影和猪主动脉样本。基于这些实验和理论分析，探索了复杂生物样品中介电常数定量测量的潜力。结论是，虽然HEI提供了基于电介质对比度的高分辨率图像，但它更适合于定性表征而不是基本电常数的定量测量。在心脏MRI领域，我们的团队开发了一种快速、鲁棒的相位标记运动跟踪技术。它是基于早期的受激回波方法。然而，在读数和伪影抑制方面的改进使这种方法进入了临床环境中实际使用的领域。它能够在14次心跳中进行二维应变映射，并将应变映射直接显示在扫描仪控制台上，几乎是实时的。它现在被用于马里兰州贝塞斯达郊区医院急诊室的病人。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未解之谜的一个非常有用的工具，这项研究正在进行中。心脏MRI的另一个研究领域是多功能造影剂，特别是与超声检查有关。

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.