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Research

Research in the Ultrasound Imaging and Therapy laboratory in the Department is focused broadly on the development and advancement of ultrasound technologies that can impact human health and disease. This research is categorized by the main pillars detailed below.

Tissue Characterization and Elasticity Imaging

As a graduate student at Drexel University, Dr. Hoyt began his research career in medical imaging with a focus on signal processing and software development. His thesis project examined the applicability of novel spectral strain estimation algorithms to improve the clinical value of ultrasound (US)-based tissue elasticity images. Initial results using clinical data collected at Thomas Jefferson University introduced the feasibility of static elasticity imaging of breast cancer. After finishing his thesis work, Dr. Hoyt continued his research in the field of elasticity imaging at the University of Rochester (UR). In collaboration with colleagues at Rensselaer Polytechnic Institute (RPI) and General Electric (GE) Global Research, Dr. Hoyt helped develop a novel dynamic tissue elasticity imaging technique and conduct the first prostate cancer study in human. He also introduced a quantitative tissue characterization technique for quantifying the dynamic viscoelastic properties of soft tissue. In a more recent collaboration with researchers at UR, Dr. Hoyt is helping develop a new tissue characterization technique for measuring the relative size of acoustic scatterers. Termed H-scan US imaging (where the ‘H’ stands for Hermite or hue), this technology has shown considerable promise for detecting an early cancer response to neoadjuvant treatment due to signature increases in cancer cell apoptotic activity. We are now investigating the use of deep learning algorithms to detect hidden patterns in these H-scan US images to improve treatment monitoring.

Quantitative US Imaging using Contrast Agents

Dr. Hoyt’s research portfolio now also focuses on the development of dynamic contrast-enhanced US (DCE-US) imaging strategies to help visualize vascular structures. After introducing new signal processing methods and custom software for analyzing DCE-US images, preclinical studies using animal models of cancer revealed that DCE-US could sensitively detect early changes in tumor perfusion before any physical changes in tumor size were evident. In fact, a study by Dr. Hoyt et al. (2015) revealed US-derived measurements of tumor perfusion and vascular morphology can give prognostic insight into breast tumor response to neoadjuvant treatment. These findings have helped motivate the exploration of novel super-resolution US (SR-US) imaging methods for improved visualization of microvascular networks down to the capillary level. While US has traditionally been a planar imaging modality, research in Dr. Hoyt’s lab is also developing volumetric US imaging techniques to help visualize tissue in 4D space.

Molecular US Imaging

Personalized medicine is becoming increasingly important to maximize effective therapy for an individual patient, reduce drug morbidity, and help contain escalating health care costs. One promising approach takes advantage of the ability of US contrast agents to be targeted to known disease biomarkers. Thus, permitting US imaging at the cellular and molecular level. In addition to the above, research in Dr. Hoyt’s laboratory has also focused broadly on the development of targeted contrast agents and strategies for molecular US imaging of tumor angiogenesis or general changes in target density with the prospect of disease staging. Using a preclinical animal model, Dr. Hoyt’s group has shown that molecular US imaging of targeted MB contrast agents can be used to detect early inflammation following acute kidney injury and tumor responses to treatment. He is now working on advanced algorithm and model development for more accurate characterization and imaging of the molecular US signal.

US-Mediated Drug Delivery and Treatment

Targeted drug delivery is one of the most ambitious goals of modern therapy. The controlled localization of a therapeutic drug to a diseased tissue site would improve delivery and treatment response. To that end, an image-guided US-based approach for enhanced delivery of anticancer drugs and gene therapy vectors is being explored by Dr. Hoyt’s group. Termed US-mediated drug therapy, early work centered on US system optimization in preclinical models of cancer. We then demonstrated that neoadjuvant US-mediated drug therapy can significantly improve anticancer response of head and neck squamous cell carcinomas dosed with either small or large molecule drugs. A more recent preclinical study showed that US-mediated drug therapy is a very promising tool for improved delivery of gene therapy adenoviral vectors and treating residual cancer cells following incomplete tumor resection (adjuvant therapy). Dr. Hoyt’s group is now set to explore the utility of image-guided US-mediated drug delivery for treatment of naturally occurring cancer in domestic animals.