Engineering Commons^™

Reconstruction Algorithms For Novel Joint Imaging Techniques In Pet, Homayoon Ranjbar

McKelvey School of Engineering Theses & Dissertations

Positron emission tomography (PET) is an important functional in vivo imaging modality with many clinical applications. Its enormously wide range of applications has made both research and industry combine it with other imaging modalities such as X-ray computed tomography (CT) or magnetic resonance imaging (MRI). The general purpose of this work is to study two cases in PET where the goal is to perform image reconstruction jointly on two data types.

The first case is the Beta-Gamma image reconstruction. Positron emitting isotopes, such as ¹¹C, ¹³N, and ¹⁸F, can be used to label molecules, and tracers, such …

Bio-Inspired Multi-Spectral And Polarization Imaging Sensors For Image-Guided Surgery, Nimrod Missael Garcia

McKelvey School of Engineering Theses & Dissertations

Image-guided surgery (IGS) can enhance cancer treatment by decreasing, and ideally eliminating, positive tumor margins and iatrogenic damage to healthy tissue. Current state-of-the-art near-infrared fluorescence imaging systems are bulky, costly, lack sensitivity under surgical illumination, and lack co-registration accuracy between multimodal images. As a result, an overwhelming majority of physicians still rely on their unaided eyes and palpation as the primary sensing modalities to distinguish cancerous from healthy tissue. In my thesis, I have addressed these challenges in IGC by mimicking the visual systems of several animals to construct low power, compact and highly sensitive multi-spectral and color-polarization sensors. I …

Extrinsic And Intrinsic Control Of Integrative Processes In Neural Systems, Anirban Nandi

McKelvey School of Engineering Theses & Dissertations

At the simplest dynamical level, neurons can be understood as integrators. That is, neurons accumulate excitation from afferent neurons until, eventually, a threshold is reached and they produce a spike. Here, we consider the control of integrative processes in neural circuits in two contexts. First, we consider the problem of extrinsic neurocontrol, or modulating the spiking activity of neural circuits using stimulation, as is desired in a wide range of neural engineering applications. From a control-theoretic standpoint, such a problem presents several interesting nuances, including discontinuity in the dynamics due to the spiking process, and the technological limitations associated with …

Novel Pet Systems And Image Reconstruction With Actively Controlled Geometry, Ke Li

McKelvey School of Engineering Theses & Dissertations

Positron Emission Tomography (PET) provides in vivo measurement of imaging ligands that are labeled with positron emitting radionuclide. Since its invention, most PET scanners have been designed to have a group of gamma ray detectors arranged in a ring geometry, accommodating the whole patient body. Virtual Pinhole PET incorporates higher resolution detectors being placed close to the Region-of-Interest (ROI) within the imaging Field-of-View (FOV) of the whole-body scanner, providing better image resolution and contrast recover. To further adapt this technology to a wider range of diseases, we proposed a second generation of virtual pinhole PET using actively controlled high resolution …

Numerical Methods For Nonlinear Optimal Control Problems And Their Applications In Indoor Climate Control, Runxin He

McKelvey School of Engineering Theses & Dissertations

Efficiency, comfort, and convenience are three major aspects in the design of control systems for residential Heating, Ventilation, and Air Conditioning (HVAC) units. In this dissertation, we study optimization-based algorithms for HVAC control that minimizes energy consumption while maintaining a desired temperature, or even human comfort in a room. Our algorithm uses a Computer Fluid Dynamics (CFD) model, mathematically formulated using Partial Differential Equations (PDEs), to describe the interactions between temperature, pressure, and air flow. Our model allows us to naturally formulate problems such as controlling the temperature of a small region of interest within a room, or to control …

Investigating Read/Write Aggregation To Exploit Power Reduction Opportunities Using Dual Supply Voltages, Gu Yunfei

McKelvey School of Engineering Theses & Dissertations

Power consumption plays an important role in computer system design today. On-chip memory structures such as multi-level cache make up a significant proportion of total power consumption of CPU or Application-Specific Integrated Circuit (AISC) chip, especially for memory-intensive application, such as floating-point computation and machine learning algorithm. Therefore, there is a clear motivation to reduce power consumption of these memory structures that are mostly consisting of Static Random-Access Memory (SRAM) blocks. In this defense, I will present the framework of a novel dual-supply-voltage scheme that uses separate voltage levels for memory read and write operations. By quantitatively analyzing the cache …

Development And Applications Of Novel Fluorescent Molecular Probe Strategies, Dolonchampa Maji

McKelvey School of Engineering Theses & Dissertations

Optical imaging and spectroscopy technologies offer the ability to provide structural and functional information in a fast, low-cost, ionizing radiation free, highly sensitive and high throughput fashion. The diverse contrast mechanisms and complementary imaging platforms form the foundation for the application of optical imaging in pre-clinical studies of pathophysiological development as well as direct clinical application as a tool for diagnosis and therapy. Fluorescence imaging techniques have been one of the most rapidly adopted methods in biology and biomedicine. Visualization of biological processes and pathologic conditions at the cellular and tissue levels largely relies on the use of exogenous fluorophores …

The Electrophysiology Of Resting State Fmri Networks, Carl David Hacker

McKelvey School of Engineering Theses & Dissertations

Traditional research in neuroscience has studied the topography of specific brain functions largely by presenting stimuli or imposing tasks and measuring evoked brain activity. This paradigm has dominated neuroscience for 50 years. Recently, investigations of brain activity in the resting state, most frequently using functional magnetic resonance imaging (fMRI), have revealed spontaneous correlations within widely distributed brain regions known as resting state networks (RSNs). Variability in RSNs across individuals has found to systematically relate to numerous diseases as well as differences in cognitive performance within specific domains. However, the relationship between spontaneous fMRI activity and the underlying neurophysiology is not …

Using Pet/Mri To Assess Hepatic Radioembolization Of Yttrium-90 Microspheres, Nichole Millward Maughan

McKelvey School of Engineering Theses & Dissertations

Radioembolization of yttrium-90 (Y-90) microspheres is used to treat primary and secondary cancers in the liver. Though this therapy has existed for decades, the treatment is not well optimized from treatment planning to post-procedural assessment. Recently, there has been a surge to utilize the small positron yield from the radioactive decay of Y-90 for post-radioembolization positron emission tomography (PET) imaging of the microsphere activity distribution. These images provide promise for dosimetry assessment, identifying extrahepatic uptake and possible under-dosed lesions that may benefit from subsequent therapy. However, due to the low positron statistics and high flux of Bremsstrahlung radiation, PET imaging …

Pet/Mr Imaging Of Hypoxic Atherosclerotic Plaque Using 64cu-Atsm, Xingyu Nie

McKelvey School of Engineering Theses & Dissertations

ABSTRACT OF THE DISSERTATION

PET/MR Imaging of Hypoxic Atherosclerotic Plaque Using 64Cu-ATSM

by

Xingyu Nie

Doctor of Philosophy in Biomedical Engineering

Washington University in St. Louis, 2017

Professor Pamela K. Woodard, Chair

Professor Suzanne Lapi, Co-Chair

It is important to accurately identify the factors involved in the progression of atherosclerosis because advanced atherosclerotic lesions are prone to rupture, leading to disability or death. Hypoxic areas have been known to be present in human atherosclerotic lesions, and lesion progression is associated with the formation of lipid-loaded macrophages and increased local inflammation which are potential major factors in the formation of vulnerable …