Bioimaging and Biomedical Optics Commons^™

Computational Design Of Fiber-Optic Probes For Biosensing, Suwarna Karna

Electrical Engineering Theses

This thesis presents a study on the optical characteristics of hollow-core photonic crystal fibers (HC-PCFs) with a band gap cladding structure and their applications in optical fiber sensing. This 800B HC-PCF exhibited excellent optical properties and has a flexible structure, which makes them suitable for a wide range of industrial applications. Finite element simulations and structural optimization designs were conducted using the surface plasmon resonance (SPR) technique to determine the optimal performance parameters of the 800B HC-PCF. The fiber was further modified using the SPR technique to improve its practical detection capabilities. The performance of the modified fiber was observed …

A Device For Measuring Acoustic Output Intensity Of Transcranial Doppler Ultrasound Transducers For Comparison With Fda Regulations, Sarah Altman, Gregory Bashford, Benjamin Hage

Honors Program: Senior Projects (Public)

Transcranial Doppler Ultrasonography (TCD) is a non-invasive methodology which can evaluate cerebral blood flow velocity in real time. Single-element focused circular transducers placed on the scalp produce ultrasound waves capable of penetrating the skull with minimal aberration, enabling measurement of the Doppler shift. As such, TCD can measure blood flow velocity in the internal carotid and vertebral arteries, as well as the arteries of the Circle of Willis: the Anterior Cerebral (ACA), Posterior Cerebral (PCA), and Middle Cerebral Arteries (MCA). Intracranial aneurysm and ischemic stroke are serious conditions in which ballooning or occlusion of cerebral vessels cause insufficient perfusion, leading …

Differentiating Axonal From Demyelinating Neuropathies Using Multiparametric Quantitative Mri Of Peripheral Nerves, Jacob D. Baraz, Stephanie Xuan, Sadaf Saba, Xue Yang, Ryan Castoro, Yang Xuan, Alison Roth, Richard D. Dortch, Jun Li, Yongsheng Chen

Medical Student Research Symposium

Objectives: To develop a multiparametric quantitative MRI (qMRI) method to track pathological changes in the peripheral neuropathies.

Background: Irrespective of the causes or types of polyneuropathies, peripheral nerves are mainly afflicted by two kinds of pathologies – axonal loss and demyelination. It is critical to differentiate between the two as treatments are different for the two conditions. While nerve conduction studies (NCS) have been used to differentiate the two pathologies in the distal nerves, there are no tools to probe the pathologies in the proximal peripheral nerves. This is particularly needed when distal nerves become non-responsive in NCS.

Methods: We …

Efficient Scopeformer: Towards Scalable And Rich Feature Extraction For Intracranial Hemorrhage Detection Using Hybrid Convolution And Vision Transformer Networks, Yassine Barhoumi

Theses and Dissertations

The field of medical imaging has seen significant advancements through the use of artificial intelligence (AI) techniques. The success of deep learning models in this area has led to the need for further research. This study aims to explore the use of various deep learning algorithms and emerging modeling techniques to improve training paradigms in medical imaging. Convolutional neural networks (CNNs) are the go-to architecture for computer vision problems, but they have limitations in mapping long-term dependencies within images. To address these limitations, the study explores the use of techniques such as global average pooling and self-attention mechanisms. Additionally, the …

Deutj: An Imagej Plugin For Improved Automatic Masking And Segmentation Of Images From Confocal Microscopy, Sunny Cui

Independent Student Projects and Publications

Due to advances in microscopic imaging, there are a plethora of biological molecules that can now be tagged and subsequentially imaged from almost any cell, organism, or tissue. However, the ability of software to analyze these images remains to be a challenge. ImageJ is open source software that allows for the processing of these images, but faces challenges when dealing with images that show weak contrast between objects of interest and background. DeutJ is an ImageJ plugin that color corrects and brightness corrects gradients that inhibit segmentation in confocal microscopy images. It can analyze hundreds of images from a given …

Session 12: Active Learning To Minimize The Possible Risk From Future Epidemics, Kc Santosh

SDSU Data Science Symposium

In medical imaging informatics, for any future epidemics (e.g., Covid-19), deep learning (DL) models are of no use as they require a large dataset as they take months and even years to collect enough data (with annotations). In such a context, active learning (or human/expert-in-the-loop) is the must, where a machine can learn from the first day with minimum possible labeled data. In unsupervised learning, we propose to build pre-trained DL models that iteratively learn independently over time, where human/expert intervenes only when it makes mistakes and for only a limited data. In our work, deep features are used to …

Estimation Of Free Water-Corrected Microscopic Fractional Anisotropy., Nico J J Arezza, Tales Santini, Mohammad Omer, Corey A Baron

Medical Biophysics Publications

Water diffusion anisotropy MRI is sensitive to microstructural changes in the brain that are hallmarks of various neurological conditions. However, conventional metrics like fractional anisotropy are confounded by neuron fiber orientation dispersion, and the relatively low resolution of diffusion-weighted MRI gives rise to significant free water partial volume effects in many brain regions that are adjacent to cerebrospinal fluid. Microscopic fractional anisotropy is a recent metric that can report water diffusion anisotropy independent of neuron fiber orientation dispersion but is still susceptible to free water contamination. In this paper, we present a free water elimination (FWE) technique to estimate microscopic …

Dataset For Manuscript: Comparing Performance Of Spectral Image Analysis Approaches For Detection Of Cellular Signals In Time-Lapse Hyperspectral Imaging Fluorescence Excitation-Scanning Microscopy, Silas J. Leavesley

BioImaging and BioSystems Research

The dataset contains raw and processed hyperspectral timelapse image data that are described in the manuscript:

Parker, M., Annamdevula, N. S., Pleshinger, D., Ijaz, Z., Jalkh, J., Penn, R., Deshpande, D., Rich, T. C. & Leavesley, S. J. Comparing Performance of Spectral Image Analysis Approaches for Detection of Cellular Signals in Time-Lapse Hyperspectral Imaging Fluorescence Excitation-Scanning Microscopy. Bioengineering 10, 642 (2023).

Patient-Specific Analysis Of Aortic Hemodynamics And Wall Shear Stresses In Patients Undergoing Pediatric Bariatric Surgery Using 2d Phase-Contrast Mri, Oluwaferanmi S. Akande, Joao Soares, Nathan Hargan, Dr. Uyen Truong, Haeung Kang, David Lanning

UROP Posters

Patient-Specific Analysis of Aortic Hemodynamics and Wall Shear Stresses in Patients Undergoing Pediatric Bariatric Surgery using 2D Phase-Contrast MRI

Feranmi Akande¹ Nathan Hargan² Haesung Kang³ David Lanning³ Uyen Truong⁴ João S. Soares¹

¹ Department of Biomedical Engineering, College of Engineering, Virginia Commonwealth University

² Department of Mechanical & Nuclear Engineering, College of Engineering, Virginia Commonwealth University

³ Department of Cardiology, Children’s Hospital of Richmond, Virginia Commonwealth University

Introduction: Severe obesity among today’s youth is a rising epidemic within the United States. Emerging research has linked childhood obesity with shortened life expectancy and early …

Multiscale And Multimodality Optical Imaging Of Brain Hemodynamics And Function, Mehrana Mohtasebi

Theses and Dissertations--Biomedical Engineering

Frequent measurement of cerebral hemodynamics is crucial for continuous assessment of brain function and health. Low-frequency oscillations (LFOs; < 0.1 Hz) have shown promise as an indicator of altered neurologic activity in the abnormal brain. Moreover, quantification of temporal correlations in LFOs across distinct brain regions enables mapping of regional neurovascular disorders. Portable diffuse optical techniques such as near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS) enable noninvasive and continuous measurements of cerebral oxygenation and cerebral blood flow (CBF), respectively. However, most NIRS/DCS systems use limited numbers of discrete light sources and detectors and thus lack combinations of high temporal/spatial resolution and large field-of-view (FOV) for brain imaging. Recent development of an innovative noncontact speckle contrast diffuse correlation tomography (scDCT) in our lab provides a low-cost and portable tool for high-density imaging of CBF distributions over large FOVs. The scDCT uses a galvo-mirror to remotely deliver coherent point near-infrared light to multiple source positions and a CMOS camera as a high-density 2-D detector array to quantify spatial fluctuations of diffuse laser speckles, resulting from movement of red blood cells. Boundary CBF data were input to a unique finite-element-method (FEM)-based reconstruction algorithm for 3-D imaging of CBF distributions. However, scDCT was hindered for extracting LFOs due to its low sampling rate. In this study, scDCT was optimized to achieve high sampling rates and fast image reconstructions by use of moving window algorithms with parallel computations (Project 1). Power spectral density (PSD) analysis was performed to investigate altered LFOs during transient cerebral ischemia in neonatal piglets. Transient cerebral ischemia caused reductions in both CBF and PSD, supporting inclusion of scDCT in the growing field of LFO analysis. One remaining limitation was the long computational time required for 3-D reconstruction, which prohibited real-time applications. To overcome this limitation, a depth-sensitive diffuse speckle contrast topography (DSCT) method was developed for analyzing scDCT data to achieve fast and high-density 2-D mapping of CBF distribution without the need of complex and time-consuming 3-D reconstructions (Project 2). New head-simulating phantoms with known optical/geometric properties were designed and fabricated to evaluate the spatial resolution and depth sensitivity of DSCT method. In-vivo experiments verified the capability of DSCT in tracking dynamic changes in CBF at different depths during CO₂ inhalation and transient cerebral ischemia in rats. In addition to preclinical studies, a low-cost, wearable, fluorescence eye loupe (FLoupe) device was invented for intraoperative visualization of brain tumor margin in the clinic (Project 3). Consistent results were observed against an expensive, large, standard fluorescence operative microscope for the guidance of tumor resection. Overall, through 3 projects this dissertation demonstrated a variety of noninvasive noncontact optical technologies (scDCT, DSCT, and FLoupe) that enabled multiscale (rodents, piglets, and humans) and …

A Wearable Fiber-Free Optical Sensor For Continuous Measurements Of Cerebral Blood Flow And Oxygenation, Xuhui Liu

Theses and Dissertations--Biomedical Engineering

Wearable technologies for continuous monitoring of cerebral hemodynamics in freely behaving subjects not only advance our understanding of cognitive processing and adaptive behavior, but also provide vital information for diagnosis and therapeutic assessment of cerebral diseases associated with hypoxia/ischemia. Wearable near-infrared diffuse optical techniques have been used at the bedside to probe deep cerebral hemodynamics, including near-infrared spectroscopy (NIRS) for cerebral oxygenation measurement and diffuse correlation spectroscopy (DCS) for cerebral blood flow (CBF) measurement, respectively. However, most systems are relatively large and expensive, and use rigid fiber-optic probes that significantly constrain subject’s movement. A novel, wearable, fiber-free diffuse speckle contrast …

Verification Of Proton Range Predictions In Proton Treatment Planning Using X-Ray Ct Or Proton Ct Imaging, Nicholas S. Yee

Graduate Research Theses & Dissertations

The objective of this paper is to compare the range errors for two treatment plans; one using x-ray CT and the other using proton CT for calculating dose distributions in an animal tissue phantom. We shot 150 MeV proton beam through a meat phantom to a film stack to measure the exponential drop of dose at the Bragg peak until zero dose remained. Plotting the depth dose curves and performing gamma analyses are two ways to quantify the proton range errors when comparing them to depth dose curves from film measurements in the phantom. The depth dose curves give us …

Advanced Modeling And Innovative Transcranial Magnetic Stimulation Coil Designs For The Treatment Of Neurological Disorders, Mohannad Tashli

Theses and Dissertations

Transcranial magnetic stimulation (TMS) is a safe, effective and non-invasive treatment for several mental and psychiatric disorders. TMS is an FDA approved treatment and is commonly applied to patients who do not respond to medications for the treatment of clinical depression, smoking cessation, obsessive-compulsive disorder and migraine. Recently, there has been an increase in the development of electromagnetic neuromodulation techniques targeted at enhancing the effectiveness of TMS devices for the treatment of mental diseases. In TMS stimulation, focality is an important factor which determines the specificity of the pulses induced in different brain tissues. The electromagnetic pulses must be confined …

Measurement Of Fluid Movement Throughout The Brain Via Multiple Magnetic Resonance Imaging Techniques During High-Definition Transcranial Direct Current Stimulation, Jack W. Beaty Mr

Dissertations and Theses

Transcranial Direct Current Stimulation (tDCS) is a non-invasive method of neuromodulation with applications in neuroscience, clinical care, and biomedical engineering. tDCS has been well established as a safe method of applying low amplitude current between two or more electrodes to alter excitation thresholds and neuroplasticity. Recently, in-vitro and clinical studies have suggested that DC stimulation can induce a transient, polarity-specific, effect of increased water exchange across the blood-brain barrier (BBB). The electroosmotic effect, the proposed phenomenon driving water exchange, is a biophysical response of charged ions moving across an oppositely-charged surface, i.e., the tight junction, when subjected to an electric …

Using Paired-Agent Imaging To Track Changes In Head And Neck Cancers After Undergoing Photodynamic Therapy Treatment, Reeham M. Choudhury

Dartmouth College Master’s Theses

Head and neck cancers affect thousands of people across the world, and photodynamic therapy (PDT) has been shown to have great potential to treat said cancers in a noninvasive manner. However, imaging head and neck cancers has been difficult, and molecular changes caused by PDT are not well-understood. Therefore, we propose the use of paired-agent imaging (PAI) to track changes in these cancers after after PDT treatment. For these studies, we primarily used benzoporphyrin derivative monoacid (BPD) for our photosensitizer, which is activated by a 690 nm laser. We first looked at changes in EGFR expression in vitro, and …

Evaluating Human Eye Features For Objective Measure Of Working Memory Capacity, Yasasi Abeysinghe, Enkelejda Kasneci (Ed.), Frederick Shic (Ed.), Mohamed Khamis (Ed.)

Computer Science Faculty Publications

Eye tracking measures can provide means to understand the underlying development of human working memory. In this study, we propose to develop machine learning algorithms to find an objective relationship between human eye movements via oculomotor plant and their working memory capacity, which determines subjective cognitive load. Here we evaluate oculomotor plant features extracted from saccadic eye movements, traditional positional gaze metrics, and advanced eye metrics such as ambient/focal coefficient , gaze transition entropy, low/high index of pupillary activity (LHIPA), and real-time index of pupillary activity (RIPA). This paper outlines the proposed approach of evaluating eye movements for obtaining an …

Ultrasensitive Tapered Optical Fiber Refractive Index, Erem Ujah, Meimei Lai, Gymama Slaughter

Electrical & Computer Engineering Faculty Publications

Refractive index (RI) sensors are of great interest for label-free optical biosensing. A tapered optical fiber (TOF) RI sensor with micron-sized waist diameters can dramatically enhance sensor sensitivity by reducing the mode volume over a long distance. Here, a simple and fast method is used to fabricate highly sensitive refractive index sensors based on localized surface plasmon resonance (LSPR). Two TOFs (l = 5 mm) with waist diameters of 5 µm and 12 µm demonstrated sensitivity enhancement at λ = 1559 nm for glucose sensing (5-45 wt%) at room temperature. The optical power transmission decreased with increasing glucose concentration due …

Brain Activity Associated With Taste Stimulation: A Mechanism For Neuroplastic Change?, Angela M. Dietsch, Ross M. Westemeyer, Douglas H. Schultz

Department of Special Education and Communication Disorders: Faculty Publications

Purpose: Neuroplasticity may be enhanced by increasing brain activation and bloodflow in neural regions relevant to the target behavior.We administered precisely formulated and dosed taste stimuli to determine whether the associated brain activity patterns included areas that underlie swallowing control.

Methods: Five taste stimuli (unflavored, sour, sweet-sour, lemon, and orange suspensions) were administered in timing-regulated and temperature-controlled 3 mL doses via a customized pump/tubing system to 21 healthy adults during functional magnetic resonance imaging (fMRI). Whole-brain analyses of fMRI data assessed main effects of taste stimulation as well as differential effects of taste profile.

Results: Differences in …

Soft X-Ray And Susceptibility Based Magnetic Resonance Imaging To Map Iron Distribution In Apples: Initial Results To Model Iron Storage In Water-Deficient Or Dehydrated Biological Tissue, Subhendra Sarkar, Eric Lobel, Evans Lespinasse, Zoya Vinokur, Analia Basilicata, Sonia Orellana, Maria Orellana, Aaliyah Salmon, Joanna Syska, Aravis Mcbroom, Jian Wang, Anam Riaz, Jody-Ann Douglas

Publications and Research

Radiology departments have contributed significantly to greenhouse gases including release of toxic imaging contrast media to environment. We feel Radiology also has several spectroscopy and imaging tools that may apply to monitor and support cleaner environmental goals. The current manuscript is one of the firsts to prompt Radiology to move in that direction by non-invasive imaging of bio metals that are less abundant in biological tissues but play key roles as co-factors in tissue structure and function. Conventional analytical tools are mostly invasive and cannot characterize the native oxidation states of bio metals. We chose carbohydrate matrix of metal-rich fruits …