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.
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