Biomedical Imaging Center

X-ray Imaging

The evolution of civilization is driven by the need for extending our capabilities. A most important way for us to sense the world is by vision. Biomedical imaging systems outperform our natural vision and become indispensible “eyes” in the fields of biology and medicine. A fascinating puzzle in history was how to achieve “an inner vision” of opaque objects. X-ray computed tomography (CT) is the first imaging modality to enable non-destructive sectional or volumetric image reconstruction of an object from x-ray shadows. Since the introduction of x-ray CT, biomedical imaging technology has been under rapid development for predictive, preventive and personalized medicine and should dramatically improve our longevity and quality of life. Our currently funded projects target x-ray CT and optical molecular tomography, multimodality and emerging possibilities.

X-ray CT Projects – We are prototyping the next generation x-ray nano-CT system for ROI-focused scanning and theoretically exact interior reconstruction (NSF/MRI 0923297, 2009-2012). Filling the performance gap between light and electron microscopic techniques, our x-ray nano-CT platform depicts details with resolution down to 50nm and has emerged as a powerful tool in various applications. However, a primary barrier to realizing the full potential of nano-CT is the aforementioned interior problem that prevents us from handling large objects and the intensive x-ray beam that may damage biological samples. To overcome these challenges, we are developing interior tomography/compressive sensing techniques. Our proposed interior nano-CT system should accelerate progress in diverse fields, such as medicine, biology, nanotechnology, material science, and energy physics. Upon completion of our project, the proposed system will be commercialized in collaboration with Xradia. In combination with our existing micro-CT and CT scanners, our multi-scale CT facility, one of the best in the world, covers 6 orders of magnitude in terms of image resolution and sample size with unique interior reconstruction capabilities.

Also, we are working on the next-generation cardiac CT architecture for better detection and quantification of cardiovascular diseases (NIH/NIBIB R01 EB011785, 2009-2012). Cardiovascular diseases are pervasive with high mortality and morbidity. There are urgent needs for significantly higher fidelity cardiac CT with substantially lower radiation dose. Although CT technology has improved from 16 to 320 detector rows and from single to dual sources, there remain challenges in terms of temporal resolution, spatial resolution and radiation dose. Based on an academic-industrial partnership between Virginia Tech and the GE Global Research Center, the goal of this project is to develop and analyze novel cardiac CT architectures and algorithms to define the next-generation cardiac CT concepts. On completion of this project, we will provide specifications and feasibility data for the most promising cardiac CT architecture(s) capable of achieving 16cm coverage, 50ms temporal resolution, 20lp/cm spatial resolution, 10HU noise level, and 5mSv effective dose simultaneously for an entire examination, This will set the stage for the second phase of the project: Actual prototyping of a next-generation cardiac CT system.

Optical Imaging BRP – Regenerative medicine devises new ways to repair or replace damaged tissues and organs for millions of patients who cannot receive transplants. A core technology is the bioengineering of a functional tissue or organ by seeding living cells onto a biodegradable scaffold and surgically implanting the construct into a patient. Tissue engineering involves extensive remodeling of cells and scaffolds. A primary barrier to progress has been the inability to monitor this dynamic complex biological process in real-time, which presents an outstanding biomedical imaging research opportunity. The NIH roadmap highlights molecular imaging that plays an instrumental role in the advancement of medicine. Now, optical molecular imaging tools have found major preclinical and clinical applications but they have not been effectively used for regenerative medicine. Therefore, we are motivated to integrate two forefront technologies – tissue engineering and optical molecular imaging – in a unified framework, and drive a paradigm shift from static assays of cellular function in biopsied tissue or 2D culture models towards systematic tomographic analysis of 3D systems.

Our BRP (Bioengineering Research Partnership) project will develop a first-of-its-kind multi-probe multi-modal optical molecular tomography system for regenerative medicine, and demonstrate its utility in assessing bioengineered blood vessels at pre- and post-implantation stages (NIH/NHLBI R01 HL098912, 2009-2014). Fluorescent probes will be used to label the tubular scaffold and two main cell types of blood vessels (endothelial cells lining the lumen, and smooth muscle cells in the wall). Optical fibers within the scaffold will deliver laser light for optical coherence tomography and excite the fluorescent probes. Innovative algorithms will be developed for fluorescence tomography. Initially, the proposed imaging system will track the development of bioengineered vessels in a bioreactor mimicking blood flow conditions. The engineered vessels will then be implanted as interposition grafts in the carotid arteries of living sheep and imaged to follow the tissue regeneration and function. This project will optimize new optical molecular imaging tools for vessel engineering and have major impacts on other areas in regenerative medicine.