Biomedical Engineering and Bioengineering Commons^™

Photoreceptor Inner Segment Morphology In Best Vitelliform Macular Dystrophy, Drew Scoles, Yusufu N. Sulai, Robert F. Cooper, Brian P. Higgins, Ryan D. Johnson, Joseph Carroll, Alfredo Dubra, Kimberly E. Stepien

Biomedical Engineering Faculty Research and Publications

PURPOSE

To characterize outer retina structure in best vitelliform macular dystrophy (BVMD) and to determine the effect of macular lesions on overlying and adjacent photoreceptors.

METHODS

Five individuals with BVMD were followed prospectively with spectral domain optical coherence tomography and confocal and nonconfocal split-detector adaptive optics scanning light ophthalmoscopy (AOSLO). The AOSLO cone photoreceptor mosaic images were obtained within and around retinal lesions. Cone density was measured inside and outside lesions. In 2 subjects, densities were compared with published measurements acquired ∼2.5 years before. One subject was imaged 3 times over a 5-month period.

RESULTS

The AOSLO imaging demonstrated that …

Characterization Of Histological Changes In The Microvasculature Of Rat Skeletal Muscle After Spinal Cord Injury, Sally Lin

Master's Theses (2009 -)

The purpose of this study was to determine whether there are histological changes in the microvasculature of rat skeletal muscle following chronic spinal cord injury both above and below the level of injury. This study is important because microvascular structure likely impacts muscle performance and cardiovascular health. To the best of our knowledge, this is the only study to investigate microvascular structure within rat skeletal muscle after spinal cord injury. We hypothesized structural remodeling would occur in both the myofibers and microvasculature, which would then manifest in differences in myofiber cross sectional area and microvascular diameter, wall thickness, wall to …

Cortical Oscillations During A Lateral Balance Perturbation While Walking, Joseph Lee

Dissertations (1934 -)

The role of sensory systems in the cortical control of dynamic balance was examined using electroencephalography (EEG) recordings during balance perturbations while walking. Specifically, we examined the impact of sensory deficits on cortical oscillations using vibratory stimuli to suppress sensory feedback and by comparing cortical oscillations during balance perturbations while walking in people with sensory deficits associated with cervical myelopathy and neurologically intact controls. Balance during walking provides a rich framework for investigating cortical control using EEG during a functionally relevant task. While this approach is promising, substantial technical challenges remain in recording and processing EEG in the noisy, artifact …

A Fourier Description Of Covariance, And Separation Of Simultaneously Encoded Slices With In-Plane Acceleration In Fmri, Mary C. Kociuba

Dissertations (1934 -)

Functional magnetic resonance imaging (fMRI) studies aim to identify localized neural regions associated with a cognitive task performed by the subject. An indirect measure of the brain activity is the blood oxygenation level dependent (BOLD) signal fluctuations observed within the complex-valued spatial frequencies measured over time. The standard practice in fMRI is to discard the phase information after image reconstruction, even with evidence of biological task-related change in the phase time-series. In the first aim of this dissertation, a complex-valued time-series covariance is derived as a linear combination of second order temporal Fourier frequency coefficients. As opposed to magnitude-only analysis, …

Engineering Synthetic Feedback To Promote Recovery Of Self-Feeding Skills In People With Sensory Deficits Due To Stroke, Alexis Krueger

Master's Theses (2009 -)

Kinesthesia refers to sensations of limb position and movement, and deficits of upper limb kinesthetic feedback are common after stroke, impairing stroke survivors’ ability to perform the fundamental reaching and stabilization behaviors needed for daily functions like self-feeding. I attempt to mitigate the negative impact of post-stroke kinesthesia deficits by evaluating the utility of vibrotactile sensory substitution to restore closed-loop kinesthetic feedback of the upper limb. As a first step, this study evaluated performance in healthy individuals during fundamental reaching, stabilization, and tracking behaviors while using supplemental vibrotactile feedback encoding either limb state information or goal-aware error information. First, I …

Evaluation Of An Actuated Wrist Orthosis For Use In Assistive Upper Extremity Rehabilitation, Devon Holley

Master's Theses (2009 -)

Cerebral palsy (CP) is a neurological condition caused by damage to motor control centers of the brain. This leads to physical and cognitive deficiencies that can reduce an individual’s quality of life. Specifically, motor deficiencies of the upper extremity can make it difficult for an individual to complete everyday tasks, including eating, drinking, getting dressed, or combing their hair. Physical therapy, involving repetitive tasks, has been shown to be effective in training normal motion of the limb by invoking the neuroplasticity of the brain and its ability to adapt in order to facilitate motor learning. Creating a device for use …

Technology-Assisted Stroke Rehabilitation In Mexico: A Pilot Randomized Trial Comparing Traditional Therapy To Circuit Training In A Robot/Technology-Assisted Therapy Gym, Karla Bustamante Valles, Sandra Montes, Maria De Jesus Madrigal, Adan Burciaga, María Elena Martínez, Michelle J. Johnson

Biomedical Engineering Faculty Research and Publications

Background

Stroke rehabilitation in low- and middle-income countries, such as Mexico, is often hampered by lack of clinical resources and funding. To provide a cost-effective solution for comprehensive post-stroke rehabilitation that can alleviate the need for one-on-one physical or occupational therapy, in lower and upper extremities, we proposed and implemented a technology-assisted rehabilitation gymnasium in Chihuahua, Mexico. The Gymnasium for Robotic Rehabilitation (Robot Gym) consisted of low- and high-tech systems for upper and lower limb rehabilitation. Our hypothesis is that the Robot Gym can provide a cost- and labor-efficient alternative for post-stroke rehabilitation, while being more or as effective as …

Monitoring Of Tissue Optical Properties During Thermal Coagulation Of Ex Vivo Tissues, Vivek K. Nagarajan, Bing Yu

Biomedical Engineering Faculty Research and Publications

Background and Objective

Real-time monitoring of tissue status during thermal ablation of tumors is critical to ensure complete destruction of tumor mass, while avoiding tissue charring and excessive damage to normal tissues. Currently, magnetic resonance thermometry (MRT), along with magnetic resonance imaging (MRI), is the most commonly used technique for monitoring and assessing thermal ablation process in soft tissues. MRT/MRI is very expensive, bulky, and often subject to motion artifacts. On the other hand, light propagation within tissue is sensitive to changes in tissue microstructure and physiology which could be used to directly quantify the extent of tissue damage. Furthermore, …

Segmental Kinematic Analysis Of Planovalgus Feet In Children With Cerebral Palsy, K. Kruger, K. Konop, Joseph Krzak, Adam Graf, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

No abstract provided.

Augmenting Sensorimotor Control Using “Goal-Aware” Vibrotactile Stimulation During Reaching And Manipulation Behaviors, Emmanouil Tzorakoleftherakis, Todd D. Murphey, Robert A. Scheidt

Biomedical Engineering Faculty Research and Publications

We describe two sets of experiments that examine the ability of vibrotactile encoding of simple position error and combined object states (calculated from an optimal controller) to enhance performance of reaching and manipulation tasks in healthy human adults. The goal of the first experiment (tracking) was to follow a moving target with a cursor on a computer screen. Visual and/or vibrotactile cues were provided in this experiment, and vibrotactile feedback was redundant with visual feedback in that it did not encode any information above and beyond what was already available via vision. After only 10 minutes of practice using vibrotactile …

Toward Translating Near-Infrared Spectroscopy Oxygen Saturation Data For The Non-Invasive Prediction Of Spatial And Temporal Hemodynamics During Exercise, Laura M. Ellwein, Margaret M. Samyn, Michael E. Danduran, Sheila M. Schindler-Ivens, Stacy Liebham, John F. Ladisa Jr.

Exercise Science Faculty Research and Publications

Image-based computational fluid dynamics (CFD) studies conducted at rest have shown that atherosclerotic plaque in the thoracic aorta (TA) correlates with adverse wall shear stress (WSS), but there is a paucity of such data under elevated flow conditions. We developed a pedaling exercise protocol to obtain phase contrast magnetic resonance imaging (PC-MRI) blood flow measurements in the TA and brachiocephalic arteries during three-tiered supine pedaling at 130, 150, and 170 % of resting heart rate (HR), and relate these measurements to non-invasive tissue oxygen saturation (StO₂) acquired by near-infrared spectroscopy (NIRS) while conducting the same protocol. Local quantification …

Co-Ops And Capstone Design: Are They Interchangeable?, Jay R. Goldberg

Biomedical Engineering Faculty Research and Publications

Many engineering schools in the United States provide opportunities for their undergraduate students to gain practical, real-world experience in their chosen disciplines. Cooperative education is a structured method of combining classroom-based education with practical work experience. A cooperative education experience, commonly known as a co-op, provides academic credit (and pay) for such an experience. Discusses the benefits of these working experiences, focusing on capstone design courses.

Functional Comparison Of Conventional Afos With The Dynamic Response Afo, Mitchell Ruble

Master's Theses (2009 -)

Ankle foot orthoses (AFOs) are commonly prescribed to provide stability and foot clearance for patients with weakened or injured musculature. The Dynamic Response AFO (DRAFO) was designed to improve proprioception at heel strike. The design includes a rigid outer shell with a cut out heel and a soft inner lining; it is typically aligned in plantarflexion and may incorporate external heel wedges. The objective of this study was to investigate the effects of the DRAFO design features and contrast its biomechanical function with that of conventional locked and articulating AFOs. The research hypotheses were: 1) DRAFO-assisted gait parameters (e.g. ankle …

Attenuation Of The Ganglion Cell Layer In A Premature Infant Revealed With Handheld Spectral Domain Optical Coherence Tomography, Mara R. Goldberg, Fouad R. Zakka, Joseph Carroll, Deborah M. Costakos

Biomedical Engineering Faculty Research and Publications

Purpose: To report on subclinical retinal abnormalities shown through handheld spectral domain optical coherence tomography on a premature infant.

Methods: Case report.

Results: The initial and follow-up exams on a premature infant revealed severely attenuated ganglion cell and nerve fiber layers. There was cystoid macular edema in both eyes at the initial visits, which resolved by the 1-year follow-up.

Discussion: Optical coherence tomography can reveal significant retinal abnormalities in premature infants which are not detectable through funduscopic exam. Documenting such findings may be useful for the comprehensive management of vision problems in children with a history of premature birth.

Evaluating Descriptive Metrics Of The Human Cone Mosaic, Robert F. Cooper, Melissa A. Wilk, Sergey Tarima, Joseph Carroll

Biomedical Engineering Faculty Research and Publications

Purpose: To evaluate how metrics used to describe the cone mosaic change in response to simulated photoreceptor undersampling (i.e., cell loss or misidentification).

Methods: Using an adaptive optics ophthalmoscope, we acquired images of the cone mosaic from the center of fixation to 10° along the temporal, superior, inferior, and nasal meridians in 20 healthy subjects. Regions of interest (n = 1780) were extracted at regular intervals along each meridian. Cone mosaic geometry was assessed using a variety of metrics − density, density recovery profile distance (DRPD), nearest neighbor distance (NND), intercell distance (ICD), farthest neighbor distance (FND), percentage of …

Image-Based Quantification Of 3d Morphology For Bifurcations In The Left Coronary Artery: Application To Stent Design, Laura M. Ellwein, David S. Marks, Raymond Q. Migrino, Dennis Foley, Sara Sherman, John F. Ladisa Jr.

Biomedical Engineering Faculty Research and Publications

Background

Improved strategies for stent‐based treatment of coronary artery disease at bifurcations require a greater understanding of artery morphology.

Objective

We developed a workflow to quantify morphology in the left main coronary (LMCA), left anterior descending (LAD), and left circumflex (LCX) artery bifurcations.

Methods

Computational models of each bifurcation were created for 55 patients using computed tomography images in 3D segmentation software. Metrics including cross‐sectional area, length, eccentricity, taper, curvature, planarity, branching law parameters, and bifurcation angles were assessed using open‐sources software and custom applications. Geometric characterization was performed by comparison of means, correlation, and linear discriminant analysis (LDA).

Results …

Mg2+ Differentially Regulates Two Modes Of Mitochondrial Ca2+ Uptake In Isolated Cardiac Mitochondria: Implications For Mitochondrial Ca2+ Sequestration, Christoph A. Blomeyer, Jason Bazil, David F. Stowe, Ranjan K. Dash, Amadou Ks Camara

Biomedical Engineering Faculty Research and Publications

The manner in which mitochondria take up and store Ca²⁺ remains highly debated. Recent experimental and computational evidence has suggested the presence of at least two modes of Ca²⁺ uptake and a complex Ca²⁺ sequestration mechanism in mitochondria. But how Mg²⁺ regulates these different modes of Ca²⁺ uptake as well as mitochondrial Ca²⁺ sequestration is not known. In this study, we investigated two different ways by which mitochondria take up and sequester Ca²⁺ by using two different protocols. Isolated guinea pig cardiac mitochondria were exposed to varying concentrations of CaCl₂ in the …

Longitudinal Imaging Of Microvascular Remodelling In Proliferative Diabetic Retinopathy Using Adaptive Optics Scanning Light Ophthalmoscopy, Toco Yuen Ping Chui, Alexander Pinhas, Alexander Gan, Moataz Razeen, Nishit Shah, Eric Cheang, Chun L. Liu, Alfredo Dubra, Richard B. Rosen

Biomedical Engineering Faculty Research and Publications

Purpose

To characterise longitudinal changes in the retinal microvasculature of type 2 diabetes mellitus (T2DM) as exemplified in a patient with proliferative diabetic retinopathy (PDR) using an adaptive optics scanning light ophthalmoscope (AOSLO).

Methods

A 35-year-old T2DM patient with PDR treated with scatter pan-retinal photocoagulation at the inferior retina 1 day prior to initial AOSLO imaging along with a 24-year-old healthy control were imaged in this study. AOSLO vascular structural and perfusion maps were acquired at four visits over a 20-week period. Capillary diameter and microaneurysm area changes were measured on the AOSLO structural maps. Imaging repeatability was established using …

Automatic Detection Of Cone Photoreceptors In Split Detector Adaptive Optics Scanning Light Ophthalmoscope Images, David Cunefare, Robert F. Cooper, Brian P. Higgins, David F. Katz, Alfredo Dubra, Joseph Carroll, Sina Farsiu

Biomedical Engineering Faculty Research and Publications

Quantitative analysis of the cone photoreceptor mosaic in the living retina is potentially useful for early diagnosis and prognosis of many ocular diseases. Non-confocal split detector based adaptive optics scanning light ophthalmoscope (AOSLO) imaging reveals the cone photoreceptor inner segment mosaics often not visualized on confocal AOSLO imaging. Despite recent advances in automated cone segmentation algorithms for confocal AOSLO imagery, quantitative analysis of split detector AOSLO images is currently a time-consuming manual process. In this paper, we present the fully automatic adaptive filtering and local detection (AFLD) method for detecting cones in split detector AOSLO images. We validated our algorithm …

An Algorithm For Constrained One-Step Inversion Of Spectral Ct Data, Rina Foygel Barber, Emil Y. Sidky, Taly Gilat Schmidt, Xiaochuan Pan

Biomedical Engineering Faculty Research and Publications

We develop a primal-dual algorithm that allows for one-step inversion of spectral CT transmission photon counts data to a basis map decomposition. The algorithm allows for image constraints to be enforced on the basis maps during the inversion. The derivation of the algorithm makes use of a local upper bounding quadratic approximation to generate descent steps for non-convex spectral CT data discrepancy terms, combined with a new convex-concave optimization algorithm. Convergence of the algorithm is demonstrated on simulated spectral CT data. Simulations with noise and anthropomorphic phantoms show examples of how to employ the constrained one-step algorithm for spectral CT …

Structural-Functional Brain Connectivity Underlying Integrative Sensorimotor Function After Stroke, Benjamin Thomas Kalinosky

Dissertations (1934 -)

In this dissertation research project, we demonstrated the relationship between the structural and functional connections across the brain in stroke survivors. We used this information to predict arm function in stroke survivors, suggesting that the tools developed through this research will be useful for prescribing individualized rehabilitation strategies in people after stroke. Current clinical methods for rehabilitating sensorimotor function after stroke are not based on the locus of injury in the brain. Instead, therapies are generalized, treating symptoms such as weakness and spasticity. This results in outcomes that are highly variable, with severity of impairment immediately following stroke as the …

Injury Risk Assessment Of The Femur In Children With Osteogenesis Imperfecta, Jessica Marie Fritz

Dissertations (1934 -)

Osteogenesis imperfecta (OI) is a genetic disorder characterized by increased bone fragility and decreased bone mass, which leads to high rates of bone fracture. OI has a prevalence of 1/5,000 to 1/10,000 in the United States. About 90% of persons with OI have a genetic mutation in the coding for collagen type I, which is the major protein of connective tissues, including bone. While its prevalence classifies it as a rare disease, it is the most common disorder of bone etiology. Until recently, little was known about the mechanics and materials of OI bone or their impact on fracture risk. …

A Principal Component Analysis Investigation Of Drop Landings For Defining Anterior Cruciate Ligament Injury Risk Factors, Emily Schaefer

Master's Theses (2009 -)

Injury to the anterior cruciate ligament (ACL) has been widely investigated through observational video analysis and laboratory based cadaveric, motion capture and computer simulation models. With the greater incidence of injury in the female population, recent emphasis has been placed on understanding ACL injury mechanisms in females. By using our understanding of injury mechanisms and prospective studies, injury prediction methods can be created. Once injury can be reliably predicted, training methods can be implemented to reduce likelihood of injury and avoid devastating consequences. There is a need for a reliable way to reduce motion capture data obtained in a laboratory …

Optimal Schedules In Multitask Motor Learning, Jeong Yoon Lee, Youngmin Oh, Sung Shin Kim, Robert A. Scheidt, Nicolas Schweighofer

Biomedical Engineering Faculty Research and Publications

Although scheduling multiple tasks in motor learning to maximize long-term retention of performance is of great practical importance in sports training and motor rehabilitation after brain injury, it is unclear how to do so. We propose here a novel theoretical approach that uses optimal control theory and computational models of motor adaptation to determine schedules that maximize long-term retention predictively. Using Pontryagin’s maximum principle, we derived a control law that determines the trial-by-trial task choice that maximizes overall delayed retention for all tasks, as predicted by the state-space model. Simulations of a single session of adaptation with two tasks show …

Alterations In Cortical Sensorimotor Connectivity Following Complete Cervical Spinal Cord Injury: A Prospective Resting-State Fmri Study, Akinwunmi Oni-Orisan, Mayank Kaushal, Wenjun Li, Jack Leschke, B. Douglas Ward, Aditya Vedantam, Benjamin Kalinosky, Matthew D. Budde, Brian D. Schmit, Shi-Jiang Li, Viashnavi Muqeet, Shekar N. Kurpad

Biomedical Engineering Faculty Research and Publications

Functional magnetic resonance imaging (fMRI) studies have demonstrated alterations during task-induced brain activation in spinal cord injury (SCI) patients. The interruption to structural integrity of the spinal cord and the resultant disrupted flow of bidirectional communication between the brain and the spinal cord might contribute to the observed dynamic reorganization (neural plasticity). However, the effect of SCI on brain resting-state connectivity patterns remains unclear. We undertook a prospective resting-state fMRI (rs-fMRI) study to explore changes to cortical activation patterns following SCI. With institutional review board approval, rs-fMRI data was obtained in eleven patients with complete cervical SCI (>2 years …

Faculty Intellectual Property In Capstone Design Projects, Jay R. Goldberg

Biomedical Engineering Faculty Research and Publications

Reports on the Capstone Design challenge, focusing on design challenges for the participants. By focusing on the design process and allowing students to gain hands-on experience in design, they help prepare students for careers in engineering. In many capstone design courses, students design a product or device to solve a problem and build and test a prototype to verify and validate the design. Student teams are often advised by some combination of industry sponsors, clinical advisors, and/or faculty advisors. Faculty advisors serve as technical advisors to the teams and provide guidance to keep them on track. They are not members …

Instrumented Lumbar Corpectomy And Spinal Reconstruction Comparing Rhbmp-2/Compression-Resistant Matrix, Rhbmp-2/Absorbable Collagen Sponge/Ceramic Granules Mixture, And Autograft In Two Different Devices: A Study In Sheep, Jeffrey M. Toth, David G. Schwartz, Jean-Piere Mobasser, Joseph Williams

Biomedical Engineering Faculty Research and Publications

Study Design. Fusion success with rhBMP-2 and autograft in titanium or PEEK corpectomy devices was evaluated in a sheep lumbar corpectomy model. The 6 treatment groups included titanium mesh or PEEK corpectomy devices filled with rhBMP-2 on a compression-resistant matrix (CRM) carrier; rhBMP-2 in a morselized absorbable collagen sponge (ACS) carrier combined with resorbable ceramic granules; and autograft.

Objective. The aim of this study was to determine fusion rates associated with 2 different preparations of rhBMP-2 as well as autograft in an instrumented ovine lumbar corpectomy model 6 months postoperatively.

Summary of Background Data. Vertebral reconstruction with corpectomy devices requires …

Effects Of Intraframe Distortion On Measures Of Cone Mosaic Geometry From Adaptive Optics Scanning Light Ophthalmoscopy, Robert F. Cooper, Yusufu N. Sulai, Adam M. Dubis, Toco Y.P. Chui, Richard B. Rosen, Michel Michaelides, Alfredo Dubra, Joseph Carroll

Biomedical Engineering Faculty Research and Publications

Purpose: To characterize the effects of intraframe distortion due to involuntary eye motion on measures of cone mosaic geometry derived from adaptive optics scanning light ophthalmoscope (AOSLO) images.

Methods: We acquired AOSLO image sequences from 20 subjects at 1.0, 2.0, and 5.08 temporal from fixation. An expert grader manually selected 10 minimally distorted reference frames from each 150-frame sequence for subsequent registration. Cone mosaic geometry was measured in all registered images (n ¼ 600) using multiple metrics, and the repeatability of these metrics was used to assess the impact of the distortions from each reference frame. In nine additional subjects, …

Assessing Photoreceptor Structure Associated With Ellipsoid Zone Disruptions Visualized With Optical Coherence Tomography, Drew Scoles, John A. Flatter, Robert F. Cooper, Christopher S. Langlo, Scott Robison, Maureen Neitz, David V. Weinberg, Mark E. Pennesi, Dennis P. Han, Alfredo Dubra, Joseph Carroll

Biomedical Engineering Faculty Research and Publications

Purpose: To compare images of photoreceptor layer disruptions obtained with optical coherence tomography (OCT) and adaptive optics scanning light ophthalmoscopy (AOSLO) in a variety of pathologic states.

Methods: Five subjects with photoreceptor ellipsoid zone disruption as per OCT and clinical diagnoses of closed-globe blunt ocular trauma (n = 2), macular telangiectasia type 2 (n = 1), blue-cone monochromacy (n = 1), or cone-rod dystrophy (n = 1) were included. Images were acquired within and around photoreceptor lesions using spectral domain OCT, confocal AOSLO, and split-detector AOSLO.

Results: There were substantial differences in the extent and appearance of the photoreceptor mosaic …

Finite Element Modeling And Analysis Applications In Osteogenesis Imperfecta, Jessica M. Fritz, Nicole M. Grosland, Peter Smith, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Understanding the biomechanics of bones in persons with osteogenesis imperfecta (OI) is a key component to further understanding the disease, optimizing treatment and quality of life, as well as injury prevention. However, it is not feasible to study bone biomechanics in vivo. Thus, modeling may play a key role in understanding how OI bones respond to the loading experienced during various activities, especially ambulation. Biomechanical modeling can provide insight into bone fracture risks, such as type and location, from single applied loads or repetitive loading. One method for obtaining this information is via a finite element analysis (FEA). FEA is …