Biomedical Engineering Faculty

Dr. Tom Royston, Ph.D.

Profile

Thomas J. Royston, Ph.D., Professor and Head of Biomedical Engineering, has directed the UIC Acoustics and Vibrations Laboratory (AVL) since 1995, which specializes in the development of novel medical imaging technology rooted in vibrations and acoustics. It has been supported by research grants from NSF, ONR, and NIH NIBIB. His current focus is the Audible Human Project (AHP). The goal of the AHP, sponsored by the NIBIB through an R01 grant, is to develop a comprehensive understanding and computational simulation model of how sound and vibration are generated and travel throughout the torso and the pulmonary system, and how this is altered by disease and injury. The outcomes of this project could impact both medical education, through improved training technology, and research by catalyzing the development of new acoustic imaging methods. Since becoming a faculty member in 1995, Dr. Royston has successfully mentored 13 PhD students (with seven more in progress) and three postdoctoral students (with one more in progress). He has also mentored dozens of undergraduate students conducting research in his lab, including several supported through NSF Research Experiences for Undergraduates (REU) programs administered by the UIC Department of Biomedical Engineering. Finally, he has mentored two high school math and science teachers working on summer projects in his lab (both for multiple summers), supported by an NSF Research Experiences for Teachers (RET) project administered by the UIC Department of Biomedical Engineering.

Description

#1) Hyperpolarized Xenon MRI
The University of Illinois Chicago (UIC) is one of 15 sites in a national consortium studying post-acute sequelae of SARS-CoV-2, also known as “long-Covid”. UIC is especially important because its diverse patient population accurately reflects the impact that the Covid pandemic has had in the U.S. and world-wide. One symptom of long-Covid is a continued shortness of breath (dyspnea) lasting for months after the initial infection. This is due to an increase in resistance to diffusion of gases across the thin membrane of the lung alveolae that separate the inhaled air from the red blood cells in the micro-vessels surrounding each of the >2million alveoli air sacs. This impedes transfer of oxygen into the blood stream and transfer of carbon dioxide out of it. The virus leaves damaged membrane cells in its wake, which can take time to be repaired, with the unknown prospect of some permanent scarring and permanently reduced gas transfer efficiency.

Hyperpolarized (HP) 129Xe(non) MR imaging can potentially quantify gas exchange efficiency. The person inhales xenon and then MRI is used to measure the increased xenon gas in the lung airways and in the red blood cells. A decreased value of in the blood relative to lungs indicates increased resistance to diffusion. Few sites in the world are able to conduct HP Xe MRI. UIC has the ability to generate HP Xe gas, but now needs to test its ability to be used in MR imaging. The Summer BEST participant will be involved in developing and testing Xenon “phantoms”, or mechanical test setups, that mimic the in vivo situation and are a necessary step in establishing HP Xe imaging of long-Covid patients at UIC.

#2) Transformation Acousto-Elastography
Dynamic Elastography quantitatively maps shear viscoelastic properties in a soft biological material by using a noninvasive means of measuring a mechanical wave pattern that is externally introduced into the material. This information can be used in medicine for diagnosis and monitoring of disease and injury, as many pathological conditions affect the viscoelastic properties of biological tissues (fibrosis, neurodegeneration, edema, scarring, tearing, tumor, necrosis, plaque). Dynamic Elastography methods work well in isotropic, homogeneous and unstressed materials far from boundaries. At boundaries there is mode conversion between shear and longitudinal waves, and other wave types are possible. Nonzero pre-stress affects wave motion independent of material properties, while at the same time it changes material properties due to nonlinearity. Stress-free infinite isotropic homogeneity is not the situation in most cases, especially when there are pathological conditions in organs or biological structures that have finite dimensions and are under nonzero pre-stress conditions, which is especially common in muscle tissue. These real-world complexities make the inverse problem of extracting viscoelastic properties from elastography measurements difficult.

Taking inspiration from relativistic mechanics and the emerging area of transformation acoustics, we have begun to formulate an entirely new approach to analysis of mechanical wave motion in anisotropic materials with finite boundaries that involves spatial (or space-time) distortion in order to make an anisotropic problem isotropic. In previous funding from NSF, Transformation Elastography (TE) was taken from a mathematical idea to an implementable algorithm, applying it to 1, 2 and 3-dimensional geometries and addressing both the forward and inverse (reconstruction) challenge.

In Transformation Acousto-Elastography, the objective is to extend the TE approach to account for complex pre-stress conditions, as is found in skeletal muscle, which can lead to finite deformations and require higher order (nonlinear) models of material properties. The Summer BEST participant will be involved in the design, development and testing of novel experimental systems (phantoms) for independently assessing the influence of material properties versus prestress fields on how mechanical waves propagate in materials like soft biological tissue. Both scanning laser Doppler vibrometry and Magnetic Resonance Elastography will be used to study these systems. This will help us to better design and interpret elastography measurements made in vivo.