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Full-Text Articles in Biomedical Engineering and Bioengineering

Cuda K-Nn: Application To The Segmentation Of The Retinal Vasculature Within Sd-Oct Volumes Of Mice, Wenxiang Deng Dec 2013

Cuda K-Nn: Application To The Segmentation Of The Retinal Vasculature Within Sd-Oct Volumes Of Mice, Wenxiang Deng

Theses and Dissertations

No abstract provided.


Novel Adaptive Reconstruction Schemes For Accelerated Myocardial Perfusion Magnetic Resonance Imaging, Sajan Goud Lingala Dec 2013

Novel Adaptive Reconstruction Schemes For Accelerated Myocardial Perfusion Magnetic Resonance Imaging, Sajan Goud Lingala

Theses and Dissertations

Coronary artery disease (CAD) is one of the leading causes of death in the world. In the United States alone, it is estimated that approximately every 25 seconds, a new CAD event will occur, and approximately every minute, someone will die of one. The detection of CAD during in its early stages is very critical to reduce the mortality rates. Magnetic resonance imaging of myocardial perfusion (MR-MPI) has been receiving significant attention over the last decade due to its ability to provide a unique view of the microcirculation blood flow in the myocardial tissue through the coronary vascular network. The ...


Modeling Of The Human Larynx With Application To The Influence Of False Vocal Folds On The Glottal Flow, Mehrdad Hosnieh Farahani Dec 2013

Modeling Of The Human Larynx With Application To The Influence Of False Vocal Folds On The Glottal Flow, Mehrdad Hosnieh Farahani

Theses and Dissertations

Human phonation is a complex phenomenon produced by multiphysics interaction of the fluid, tissue and acoustics fields. Despite recent advancement, little is known about the effect of false vocal folds on the fluid dynamics of the glottal flow. Recent investigations have hypothesized that this pair of tissue can affect the laryngeal flow during phonation. This hypothesis was tested both computationally and experimentally in this dissertation. The computations were performed using an incompressible solver developed in fixed Cartesian grid with a second order sharp immersed-boundary formulation while the experiments were carried out in a low-speed wind tunnel with physiologic speeds and ...


Machine-Learning Based Automated Segmentation Tool Development For Large-Scale Multicenter Mri Data Analysis, Eun Young Kim Dec 2013

Machine-Learning Based Automated Segmentation Tool Development For Large-Scale Multicenter Mri Data Analysis, Eun Young Kim

Theses and Dissertations

Background: Volumetric analysis of brain structures from structural Mag- netic Resonance (MR) images advances the understanding of the brain by providing means to study brain morphometric changes quantitatively along aging, development, and disease status. Due to the recent increased emphasis on large-scale multicenter brain MR study design, the demand for an automated brain MRI processing tool has increased as well. This dissertation describes an automatic segmentation framework for subcortical structures of brain MRI that is robust for a wide variety of MR data.

Method: The proposed segmentation framework, BRAINSCut, is an inte- gration of robust data standardization techniques and machine-learning ...


Incorporating Sheet-Likeness Information In Intensity-Based Lung Ct Image Registration, Yang Wook Kim Jul 2013

Incorporating Sheet-Likeness Information In Intensity-Based Lung Ct Image Registration, Yang Wook Kim

Theses and Dissertations

Image registration is a useful technique to measure the change between two or more images. Lung CT image registration is widely used an non-invasive method to measure the lung function changes. Non-invasive lung function measurement accuracy highly depends on lung CT image registration accuracy. Improving the registration accuracy is an important issue.

In this thesis, we propose incorporating information of the anatomical structure of the lung (fissures) as an additional cost function of the lung CT image registration. The intensity-based similarity measurement method (sum of the squared tissue volume differences) is also used to complement lung tissue information matching. However ...


Heterogeneous Finite Element Stress Analysis Of Abdominal Aortic Aneurysms : Comparison Between Ruptured And Unruptured Lesions, Timothy Kwang-Joon Chung Jul 2013

Heterogeneous Finite Element Stress Analysis Of Abdominal Aortic Aneurysms : Comparison Between Ruptured And Unruptured Lesions, Timothy Kwang-Joon Chung

Theses and Dissertations

Abdominal Aortic Aneurysm (AAA) rupture remains a leading cause of death in westernized countries. Much remains to be understood on the biomechanics of rupture. It is not clear whether rupture is predominantly a phenomenon at the material level (aneurysm wall weakening) or due to abnormally elevated tissue wall tension (stress resultant). A computational study involving 4 ruptured and 9 unruptured abdominal aortic aneurysms (AAA) was conducted to test if ruptured aneurysms were subject to a higher pressure induced wall tension than unruptured aneurysms. The unique aspect of this study is that, regional variations in material properties (thickness, stiffness, failure strength ...


Clubfoot Image Classification, Amanda Marie De Hoedt Jul 2013

Clubfoot Image Classification, Amanda Marie De Hoedt

Theses and Dissertations

Clubfoot is a congenital foot disorder that, left untreated, can limit a person's mobility by making it difficult and painful to walk. Although inexpensive and reliable treatment exists, clubfoot often goes untreated in the developing world, where 80% of cases occur.

Many nonprofit and non-governmental organizations are partnering with hospitals and clinics in the developing world to provide treatment for patients with clubfoot, and to train medical personnel in the use of these treatment methods.

As a component of these partnerships, clinics and hospitals are collecting patient records. Some of this patient information, such as photographs, requires expert quality ...


Detecting Activity-Evoked Ph Changes In Human Brain, Hye Young Heo Jul 2013

Detecting Activity-Evoked Ph Changes In Human Brain, Hye Young Heo

Theses and Dissertations

Localized pH changes have been suggested to occur in the brain during normal function. However, a lack of methods for non-invasively measuring pH with high spatial and temporal resolution limits current knowledge of brain pH dynamics. Here I report that a magnetic resonance imaging (MRI) strategy named T1 relaxation in the rotating frame (T) is sufficiently sensitive to detect widespread pH changes in the mouse and human brain evoked by systemically manipulating carbon dioxide (CO2) or bicarbonate (HCO3). Moreover, T detected changes suggesting a localized acidosis in the human visual cortex induced by a flashing ...


Surgical Simulation Training Models For Orthopaedic Fracture Surgery, Gary Thomas Ohrt Jul 2013

Surgical Simulation Training Models For Orthopaedic Fracture Surgery, Gary Thomas Ohrt

Theses and Dissertations

Articular fracture reduction is a complex surgical task that requires surgeons to be competent at multiple surgical skills to successfully complete. The list of skills needed includes the ability to use fluoroscopic images to build a 3D mental model of the fracture during reconstruction, the proper handling and use of surgical instruments, how to manipulate the fracture fragment into a reduced configuration with minimal hand motion, proper k-wire placement, and the preservation of surrounding soft tissues. Current training methodology is based on an apprenticeship model. The resident learns by watching a senior surgeon, and then preforms the procedure on live ...


Development Of A Novel Balance Assessment Tool And Its Validation In The Study Of Patients With Symptomatic Spinal Deformity, Monica Paliwal Jul 2013

Development Of A Novel Balance Assessment Tool And Its Validation In The Study Of Patients With Symptomatic Spinal Deformity, Monica Paliwal

Theses and Dissertations

The prevalence of scoliosis in those over age 60 varies from 39%-68%. Common presenting symptoms include back pain, radiculopathy, and progressive deformity. Radiographic characteristics have been previously described that correlate with these symptoms including vertebral spondylolisthesis, endplate obliquity, lumbar hypolordosis, thoracolumbar junction kyphosis and positive sagittal balance. Nevertheless, asymptomatic volunteers present with similar spinal deformities. It is likely that other factors such as age, body habitus, and exercise capacity affect or outweigh the severity of radiographic parameters. The ability to maintain the center of gravity of the body within the cone of economy results from a combination of alignment ...


Discriminating Chondrogenic Progenitor Cells (Cpcs) As A Distinct Cell Type, Apart From Normal Chondrocytes, Cheng Zhou Jul 2013

Discriminating Chondrogenic Progenitor Cells (Cpcs) As A Distinct Cell Type, Apart From Normal Chondrocytes, Cheng Zhou

Theses and Dissertations

Articular cartilage is an avascular, aneural, and alymphatic tissue with a structure consisting of a superficial, a middle and a deep zone, overlie a calcified zone at the cartilage border between. Each zone has biological and mechanical properties. Self-repair of damaged cartilage seldom if ever occurs, and joint injuries that harm cartilage surfaces often result in osteoarthritis. This has prompted researchers to explore diverse approaches to cartilage regeneration.

The superficial zone shows the highest cellularity and the lowest matrix density. Cartilage cells (chondrocytes) residing in the superficial zone had been thought to be a subpopulation of chondrocytes. However, our laboratory ...


Quantitative Assessment Of Scatter Correction Techniques Incorporated In Next Generation Dual-Source Computed Tomography, Sean David Mobberley May 2013

Quantitative Assessment Of Scatter Correction Techniques Incorporated In Next Generation Dual-Source Computed Tomography, Sean David Mobberley

Theses and Dissertations

Accurate, cross-scanner assessment of in-vivo air density used to quantitatively assess amount and distribution of emphysema in COPD subjects has remained elusive. Hounsfield units (HU) within tracheal air can be considerably more positive than -1000 HU. With the advent of new dual-source scanners which employ dedicated scatter correction techniques, it is of interest to evaluate how the quantitative measures of lung density compare between dual-source and single-source scan modes. This study has sought to characterize in-vivo and phantom-based air metrics using dual-energy computed tomography technology where the nature of the technology has required adjustments to scatter correction.

Anesthetized ovine (N ...


Computational Methods For Efficient Exome Sequencing-Based Genetic Testing, Adam Peter Deluca May 2013

Computational Methods For Efficient Exome Sequencing-Based Genetic Testing, Adam Peter Deluca

Theses and Dissertations

Exome sequencing, the process of sequencing the set of all known exons simultaneously using next-generation sequencing technology, has dramatically changed the landscape of genetic research and genetic testing. The incredible volume of data produced by these experiments creates challenges in: 1) annotating the affects of observed variants, 2) filtering to remove noise, 3) identifying plausible disease-causing variants, and 4) validating experimental results. Here we will present a series of bioinformatic tools and techniques intended to address these challenges with exome sequencing and associated validation experiments.

First, we will present the Automated Sequence Analysis Pipeline (ASAP), a tool for the efficient ...


Regional Pulmonary Function Analysis Using Image Registration And 4dct, Kaifang Du May 2013

Regional Pulmonary Function Analysis Using Image Registration And 4dct, Kaifang Du

Theses and Dissertations

Current radiation therapy (RT) planning for limiting lung toxicity is based on a uniform lung function with little consideration to the spatial and temporal pattern of lung function. Establishment of relationships between radiation dose and changes in pulmonary function can help predict and reduce the RT-induced pulmonary toxicity. Baseline measurement uncertainty of pulmonary function across scans needs to be assessed, and there is a great interest to compensate the pulmonary function for respiratory effort variations.

Respiratory-gated 4DCT imaging and image registration can be used to estimate the regional lung volume change by a transformation-based ventilation metric which is computed directly ...


Three Dimensional Fluid Structural Interaction Of Tissue Valves, Vijay Govindarajan May 2013

Three Dimensional Fluid Structural Interaction Of Tissue Valves, Vijay Govindarajan

Theses and Dissertations

This thesis presents a stable fluid structural interaction technique to simulate the dynamics of tissue valves including bio-prosthetic heart valves and natural heart valves under physiological Reynolds numbers. A partitioned approach is implemented where the equations governing the flow and the displacement of the structure are solved using two distinct solvers. A FEAP based solid solver is strongly coupled to the p-ELAFINT flow solver using subiteration procedure. The flow solver has been massively parallelized so that the domain can be distributed among several processors. The fixed Cartesian method with adaptive mesh refinement in p-ELAFINT enables us to perform fast and ...


Biomechanical Implications Of Congenitally Bicuspid Aortic Valves: A Finite Element Analysis Of Patient-Specific Geometry, Paul Nicholas Jermihov May 2013

Biomechanical Implications Of Congenitally Bicuspid Aortic Valves: A Finite Element Analysis Of Patient-Specific Geometry, Paul Nicholas Jermihov

Theses and Dissertations

This thesis introduces a framework aimed at developing an aid for physicians to diagnose and manage failing aortic valves using finite element (FE) simulations. The bicuspid aortic valve (BAV) is the most commonly observed valvular defect (Sievers et al. 2007) and therefore used to investigate the clinical utility of FE-based mechanical simulations. For the analysis, patient data was collected using real-time 3D echocardiography (rt3DE) of five normal valves and three pathological. The valve geometries were reconstructed into 3D models including the sinus and leaflet structures. An FE analysis was completed on the models, and the results were critically analyzed and ...


The Effect Of Transcranial Direct Current Stimulation On The Behavioral And Neurophysiological Performance Of Healthy Subjects During Reaching, Ryan Michael Chapman May 2013

The Effect Of Transcranial Direct Current Stimulation On The Behavioral And Neurophysiological Performance Of Healthy Subjects During Reaching, Ryan Michael Chapman

Theses and Dissertations

It is well established that cathodal transcranial direct current stimulation (tDCS) can decrease the excitability of the primary motor cortex (M1) in humans. Despite the cortical inhibition caused by cathodal tDCS, it remains unknown how this intervention alters unrestrained dynamic reaching movements qualitatively. Accordingly, we designed this study to examine how cathodal tDCS impacts unrestrained dynamic reaching as measured by qualitative kinematic features and electromyography (EMG). Ten young, healthy adult subjects were recruited to participate in a two day protocol involving repetitively reaching to two different targets (large and small) both before and following cathodal tDCS applied over the contralateral ...


Development Of A Lumbar Facet Joint Replacement, Amy Jo Criswell May 2013

Development Of A Lumbar Facet Joint Replacement, Amy Jo Criswell

Theses and Dissertations

A majority of the American population will experience low-back pain during their lifetime. With this debilitating condition affecting more people every day, a solution is required to help the population. One of the causes of low-back pain is facet degeneration. Currently, there are no replacement devices on the market that solves this issue.

This thesis presents a design of a facet joint replacement to reduce low-back pain due to facet degeneration. A finite element model of the lumbar spine (L3-L5) was developed to evaluate the implant. Range of motion (ROM), facet contact forces and intervertebral disc stresses were compared for ...


The Use Of Surrounding Lung Parenchyma For The Automated Classification Of Pulmonary Nodules, Samantha Kirsten Nowik Dilger May 2013

The Use Of Surrounding Lung Parenchyma For The Automated Classification Of Pulmonary Nodules, Samantha Kirsten Nowik Dilger

Theses and Dissertations

Lung cancer is the leading cause of cancer-related death for both men and women in the United States, despite being the second-most frequent cancer diagnosis for both sexes. This high mortality rate is due to the majority of cases being diagnosed after the primary lung cancer has metastasized. In an effort to reduce mortality associated with lung cancer by diagnosing lung cancer at an earlier stage, screening of high-risk populations has been employed. One screening tool, computed tomography (CT), has been shown to reduce mortality by 20%, compared to screening for lung cancer by chest x-ray. This was achieved by ...


Biomechanics Of Failure Modalities In Total Hip Arthroplasty, Jacob Matthias Elkins May 2013

Biomechanics Of Failure Modalities In Total Hip Arthroplasty, Jacob Matthias Elkins

Theses and Dissertations

Total hip arthroplasty (THA) is the treatment of choice to relieve joint pain and loss of mobility as a result of advanced stage osteoarthritis or other hip pathologies. Despite their general success, THAs do fail, with revision rates estimated near 5% per year. Instability, defined as the complete subluxation (dislocation) of the femoral head from the acetabular socket - which usually occurs due to implant impingement - has recently supplanted wear-induced osteolytic aseptic loosening as the leading cause of failure in THA. Soft tissue integrity has long been recognized as influencing joint stability, and therefore there has been great interest recently in ...


New Methodologies For Evaluating Human Biodynamic Response And Discomfort During Seated Whole-Body Vibration Considering Multiple Postures, Jonathan Deshaw May 2013

New Methodologies For Evaluating Human Biodynamic Response And Discomfort During Seated Whole-Body Vibration Considering Multiple Postures, Jonathan Deshaw

Theses and Dissertations

The lack of adequate equipment and measurement tools in whole-body vibration has imposed significant constraints on what can be measured and what can be investigated in the field. Most current studies are limited to single direction measurements while focusing on simple postures. Besides the limitation in measurement, most of the current biomechanical measures, such as the seat-to-head transmissibility, have discrepancies in the way they are calculated across different labs. Additionally, this field lacks an important measure to quantify the subjective discomfort of individuals, especially when sitting with different postures or in multiple-axis vibration.

This work begins by explaining discrepancies in ...