New Non-invasive IMAGING methods for biomedical applications

在过去的一年里，该项目主要在两个领域开展工作，即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。两者都揭示了有关组织电特性的信息，如离子和大分子的迁移率。霍耳效应三维断层扫描已在体模和猪主动脉样本中得到证实。基于这些实验和理论分析，探索了复杂生物样品介电常数定量测量的潜力。得出的结论是，虽然HEI提供了高分辨率的图像与基于电介质的对比度，它是更适合于定性表征比定量测量的基本电常数。 在心脏磁共振成像领域，我们的团队开发了一种相位标记的运动跟踪技术，该技术快速且鲁棒。它是基于早期的受激回波方法。然而，读数和伪影抑制的改进使该方法进入临床环境中的实际使用领域。它能够在14次心跳中进行2D应变标测，并以接近真实的时间直接在扫描仪控制台上显示应变图。它现在用于通过急诊室在郊区医院，贝塞斯达，MD入院的患者。与临床应用的优化平行，该技术也是研究心脏生物力学中未回答问题的非常有用的工具，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，特别是与超声心动图相关的造影剂。

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.