Biomedical Engineering and Bioengineering Commons^™

Differential Cortical Activation During The Perception Of Moving Objects Along Different Trajectories, Finnegan J. Calabro, Scott A. Beardsley, Lucia M. Vaina

Biomedical Engineering Faculty Research and Publications

Detection of 3D object-motion trajectories depends on the integration of two distinct visual cues: translational displacement and looming. Electrophysiological studies have identified distinct neuronal populations, whose activity depends on the precise motion cues present in the stimulus. This distinction, however, has been less clear in humans, and it is confounded by differences in the behavioral task being performed. We analyzed whole-brain fMRI, while subjects performed a common time-to-arrival task for objects moving along three trajectories: moving directly towards the observer (collision course), with trajectories parallel to the line of sight (passage course), and with trajectories perpendicular to the line of …

Exercise-Induced Alterations In Sympathetic-Somatomotor Coupling In Incomplete Spinal Cord Injury, Tanya Onushko, Gordhan B. Mahtani, Gabrielle Brazg, T. George Hornby, Brian D. Schmit

Biomedical Engineering Faculty Research and Publications

The aim of this study was to understand how high- and low-intensity locomotor training (LT) affects sympathetic-somatomotor (SS) coupling in people with incomplete spinal cord injury (SCI). Proper coupling between sympathetic and somatomotor systems allows controlled regulation of cardiovascular responses to exercise. In people with SCI, altered connectivity between descending pathways and spinal segments impairs sympathetic and somatomotor coordination, which may have deleterious effects during exercise and limit rehabilitation outcomes. We postulated that high-intensity LT, which repeatedly engages SS systems, would alter SS coupling. Thirteen individuals (50 ± 7.2 years) with motor incomplete spinal cord injuries (American Spinal Injury Association …

Supplemental Vibrotactile Feedback Of Real-Time Limb Position Enhances Precision Of Goal-Directed Reaching, Nicoletta Risi, Valay Shah, Leigh A. Mrotek, Maura Casadio, Robert A. Scheidt

Biomedical Engineering Faculty Research and Publications

We examined vibrotactile stimulation as a form of supplemental limb state feedback to enhance planning and ongoing control of goal-directed movements. Subjects wore a two-dimensional vibrotactile display on their nondominant arm while performing horizontal planar reaching with the dominant arm. The vibrotactile display provided feedback of hand position such that small hand displacements were more easily discriminable using vibrotactile feedback than with intrinsic proprioceptive feedback. When subjects relied solely on proprioception to capture visuospatial targets, performance was degraded by proprioceptive drift and an expansion of task space. By contrast, reach accuracy was enhanced immediately when subjects were provided vibrotactile feedback …

A Two Alternative Forced Choice Method For Assessing Vibrotactile Discrimination Thresholds In The Lower Limb, Riccardo Iandolo, Marta Caré, Valay Shah, Simona Schiavi, Giula Bommarito, Giacomo Boffa, Psiche Giannoni, Matilde Inglese, Leigh A. Mrotek, Robert A. Scheidt, Maura Casadio

Biomedical Engineering Faculty Research and Publications

The development of an easy to implement, quantitative measure to examine vibration perception would be useful for future application in clinical settings. Vibration sense in the lower limb of younger and older adults was examined using the method of constant stimuli (MCS) and the two-alternative forced choice paradigm. The focus of this experiment was to determine an appropriate stimulation site on the lower limb (tendon versus bone) to assess vibration threshold and to determine if the left and right legs have varying thresholds. Discrimination thresholds obtained at two stimulation sites in the left and right lower limbs showed differences in …

Computational Characterization Of The Cellular Origins Of Electroencephalography, Shane Hesprich

Master's Theses (2009 -)

Electroencephalography (EEG) is a non-invasive technique used to measure brain activity. Despite its near ubiquitous presence in neuroscience, very little research has gone into connecting the electrical potentials it measures on the scalp to the underlying network activity which generates those signals. This results in most EEG analyses being more macroscopically focused (e.g. coherence and correlation analyses). Despite the many uses of macroscopically focuses analyses, limiting research to only these analyses neglects the insights which can be gained from studying network and microcircuit architecture. The ability to study these things through non-invasive techniques like EEG depends upon the ability to …

Cerebellar Source Localization Using Event-Related Potentials In A Simple Motor Task, Efrain Torres, Scott A. Beardsley

Biomedical Engineering Faculty Research and Publications

Electroencephalography (EEG) is widely used to characterize the temporal patterns of electrical activity, primarily associated with neocortex. Traditionally, the sensitivity of EEG to cerebellar activity has been considered limited with the electrical potentials assumed to stem from cortical pyramidal cells. This study leverages recent work examining the structure, organization, and synchrony of purkinje neurons to promote local field potentials measured by EEG. In conjunction with high fidelity EEG recording and source imaging analysis we examined the feasibility of using current EEG systems to characterize cerebellar function in a series of simple motor tasks. Distributed source imaging analysis revealed consistent task-related …

Kinematic Foot Types In Youth With Pes Planovalgus Secondary To Cerebral Palsy, Juliet Amene, Joseph J. Krzak, Karen M. Kruger, Logan Killen, Haluk Altiok, Peter A. Smith, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Background

Kinematic variability of the foot and ankle segments exists during ambulation among individuals with pes planovalgus (PPV) secondary to cerebral palsy (CP). Clinicians have previously recognized such variability through classification schemes to identify subgroups of individuals, but have been unable to identify kinematic foot types.

Research question

The purpose of this work was to identify kinematic foot types among children with PPV secondary to CP using 3-dimensional multi-segment foot and ankle kinematics during gait as inputs for principal component analysis (PCA) and K-means cluster analysis.

Methods

In a single assessment session, multi-segment foot and ankle kinematics using the …

A Fast, Linear Boltzmann Transport Equation Solver For Computed Tomography Dose Calculation (Acuros Ctd), Adam Wang, Alexander Maslowski, Todd Wareing, Josh Star-Lack, Taly Gilat-Schmidt

Biomedical Engineering Faculty Research and Publications

Purpose

To improve dose reporting of CT scans, patient‐specific organ doses are highly desired. However, estimating the dose distribution in a fast and accurate manner remains challenging, despite advances in Monte Carlo methods. In this work, we present an alternative method that deterministically solves the linear Boltzmann transport equation (LBTE), which governs the behavior of x‐ray photon transport through an object.

Methods

Our deterministic solver for CT dose (Acuros CTD) is based on the same approach used to estimate scatter in projection images of a CT scan (Acuros CTS). A deterministic method is used to compute photon fluence within the …

Attitudes Toward Failure In Capstone Design Projects, Jay R. Goldberg

Biomedical Engineering Faculty Research and Publications

While working in industry during the 1980s and 1990s, project failures were to be avoided at all costs. For engineers in the medical device industry, these failures could be in the form of: 1) an idea for a new product or feature that eventually failed due to technical infeasibility, regulatory hurdles, lack of market interest, or difficulty in manufacturing; 2) a prototype that did not function as required; or 3) an animal or human clinical study that yielded poor results. They typically resulted in significant project delays, wasted time and money, and lost revenues, and often led to lower raises, …

Computational Characterization Of The Cellular Origins Of Electroencephalography, Shane Hesprich, Scott A. Beardsley

Biomedical Engineering Faculty Research and Publications

Despite the widespread use of Electroecephalography (EEG) as an imaging modality, neural generators of current dipoles measured by EEG at the scalp are not fully understood. Here, we use two morphologically accurate multicompartments neuron models (layer IV pyramidal cell and layer V spiny stellate cell) to characterize how spiking neurons generate current dipoles in response to synaptic input. The simulations indicate that the dipole generated by synaptic inputs required to drive a pyramidal cell to threshold is smaller than the dipole associated the action potential itself. These results suggest a greater role of spiking neural activity toward EEG signals measured …

Estimating The Spectrum In Computed Tomography Via Kullback–Leibler Divergence Constrained Optimization, Wooseok Ha, Emil Y. Sidky, Rina Foygel Barber, Taly Gilat Schmidt, Xiaochuan Pan

Biomedical Engineering Faculty Research and Publications

Purpose

We study the problem of spectrum estimation from transmission data of a known phantom. The goal is to reconstruct an x‐ray spectrum that can accurately model the x‐ray transmission curves and reflects a realistic shape of the typical energy spectra of the CT system.

Methods

Spectrum estimation is posed as an optimization problem with x‐ray spectrum as unknown variables, and a Kullback–Leibler (KL)‐divergence constraint is employed to incorporate prior knowledge of the spectrum and enhance numerical stability of the estimation process. The formulated constrained optimization problem is convex and can be solved efficiently by use of the exponentiated‐gradient (EG) …

Ct Automated Exposure Control Using A Generalized Detectability Index, P. Khobragade, Franco Rupcich, Jiahua Fan, Dominic J. Crotty, Naveen M. Kulkarni, Stacy D. O'Connor, W. Dennis Foley, Taly Gilat Schmidt

Biomedical Engineering Faculty Research and Publications

Purpose

Identifying an appropriate tube current setting can be challenging when using iterative reconstruction due to the varying relationship between spatial resolution, contrast, noise, and dose across different algorithms. This study developed and investigated the application of a generalized detectability index (d'_gen) to determine the noise parameter to input to existing automated exposure control (AEC) systems to provide consistent image quality (IQ) across different reconstruction approaches.

Methods

This study proposes a task‐based automated exposure control (AEC) method using a generalized detectability index (d'_gen). The proposed method leverages existing AEC methods that are based on a prescribed …

Spatial And Temporal Influences On Discrimination Of Vibrotactile Stimuli On The Arm, Valay Shah, Maura Casadio, Robert A. Scheidt, Leigh A. Mrotek

Biomedical Engineering Faculty Research and Publications

Body–machine interfaces (BMIs) provide a non-invasive way to control devices. Vibrotactile stimulation has been used by BMIs to provide performance feedback to the user, thereby reducing visual demands. To advance the goal of developing a compact, multivariate vibrotactile display for BMIs, we performed two psychophysical experiments to determine the acuity of vibrotactile perception across the arm. The first experiment assessed vibration intensity discrimination of sequentially presented stimuli within four dermatomes of the arm (C5, C7, C8, and T1) and on the ulnar head. The second experiment compared vibration intensity discrimination when pairs of vibrotactile stimuli were presented simultaneously vs. sequentially …

Automated Quantification And Evaluation Of Motion Artifact On Coronary Ct Angiography Images, Hongfeng Ma, Eric Gros, Scott G. Baginski, Zachary R. Laste, Naveen M. Kulkarni, Darin Okerlund, Taly Gilat Schmidt

Biomedical Engineering Faculty Research and Publications

Abstract

Purpose

This study developed and validated a Motion Artifact Quantification algorithm to automatically quantify the severity of motion artifacts on coronary computed tomography angiography (CCTA) images. The algorithm was then used to develop a Motion IQ Decision method to automatically identify whether a CCTA dataset is of sufficient diagnostic image quality or requires further correction.

Method

The developed Motion Artifact Quantification algorithm includes steps to identify the right coronary artery (RCA) regions of interest (ROIs), segment vessel and shading artifacts, and to calculate the motion artifact score (MAS) metric. The segmentation algorithms were verified against ground‐truth manual segmentations. The …

Assessment Of A Markerless Motion Analysis System For Manual Wheelchair Application, Jacob Rammer, Brooke A. Slavens, Joseph Krzak, Jack M. Winters, Susan A. Riedel, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Background

Wheelchair biomechanics research advances accessibility and clinical care for manual wheelchair users. Standardized outcome assessments are vital tools for tracking progress, but there is a strong need for more quantitative methods. A system offering kinematic, quantitative detection, with the ease of use of a standardized outcome assessment, would be optimal for repeated, longitudinal assessment of manual wheelchair users’ therapeutic progress, but has yet to be offered.

Results

This work evaluates a markerless motion analysis system for manual wheelchair mobility in clinical, community, and home settings. This system includes Microsoft® Kinect® 2.0 sensors, OpenSim musculoskeletal modeling, and an automated detection, …

Papaverine And Its Derivatives Radiosensitize Solid Tumors By Inhibiting Mitochondrial Metabolism, Martin Benej, Xiangqian Hong, Sandip Vibhute, Sabina Scott, Jinghai Wu, Edward Graves, Quynh-Thu Le, Albert C. Koong, Amato J. Giaccia, Bing Yu, Ching-Shih Chen, Ioanna Papandreou, Nicholas C. Denko

Biomedical Engineering Faculty Research and Publications

Tumor hypoxia reduces the effectiveness of radiation therapy by limiting the biologically effective dose. An acute increase in tumor oxygenation before radiation treatment should therefore significantly improve the tumor cell kill after radiation. Efforts to increase oxygen delivery to the tumor have not shown positive clinical results. Here we show that targeting mitochondrial respiration results in a significant reduction of the tumor cells’ demand for oxygen, leading to increased tumor oxygenation and radiation response. We identified an activity of the FDA-approved drug papaverine as an inhibitor of mitochondrial complex I. We also provide genetic evidence that papaverine’s complex I inhibition …

Detection Of Hydrogen Peroxide Production In The Isolated Rat Lung Using Amplex Red, Said H. Audi, Nina Friedly, Ranjan K. Dash, Andreas M. Beyer, Anne V. Clough, Elizabeth R. Jacobs

Biomedical Engineering Faculty Research and Publications

The objectives of this study were to develop a robust protocol to measure the rate of hydrogen peroxide (H₂O₂) production in isolated perfused rat lungs, as an index of oxidative stress, and to determine the cellular sources of the measured H₂O₂ using the extracellular probe Amplex red (AR). AR was added to the recirculating perfusate in an isolated perfused rat lung. AR’s highly fluorescent oxidation product resorufin was measured in the perfusate. Experiments were carried out without and with rotenone (complex I inhibitor), thenoyltrifluoroacetone (complex II inhibitor), antimycin A (complex III inhibitor), potassium …

Early Term Effects Of Rhbmp-2 On Pedicle Screw Fixation In A Sheep Model: Histomorphometric And Biomechanical Analyses, Jeffrey M. Toth, Mei Wang, Chetan Patel, Akshi Arora

Biomedical Engineering Faculty Research and Publications

Background: The effects of recombinant human bone morphogenetic protein-2 (rhBMP-2) on pedicle screw pullout force and its potential to improve spinal fixation have not previously been investigated. rhBMP-2 on an absorbable collagen sponge (ACS) carrier was delivered in and around cannulated and fenestrated pedicle screws in a sheep lumbar spine instability model. Two control groups (empty screw and ACS with buffer) were also evaluated. We hypothesized that rhBMP-2 could stimulate bone growth in and around the cannulated and fenestrated pedicle screws to improve early bone purchase.

Methods: Eight skeletally mature sheep underwent destabilizing laminectomies at L2–L3 and L4–L5 followed by …

Technical Note: Enhancing Soft Tissue Contrast And Radiation‐Induced Image Changes With Dual‐Energy Ct For Radiation Therapy, George Noid, An Tai, Diane Schott, Nilesh Mistry, Yu Liu, Taly Gilat Schmidt, Jared R. Robbins, X. Allen Li

Biomedical Engineering Faculty Research and Publications

Purpose

The purpose of this work is to investigate the use of low‐energy monoenergetic decompositions obtained from dual‐energy CT (DECT) to enhance image contrast and the detection of radiation‐induced changes of CT textures in pancreatic cancer.

Methods

The DECT data acquired for 10 consecutive pancreatic cancer patients during routine nongated CT‐guided radiation therapy (RT) using an in‐room CT (Definition AS Open, Siemens Healthcare, Malvern, PA) were analyzed. With a sequential DE protocol, the scanner rapidly performs two helical acquisitions, the first at a tube voltage of 80 kVp and the second at a tube voltage of 140 kVp. Virtual monoenergetic …

Application Of Fractal Dimension For Quantifying Noise Texture In Computed Tomography Images, P. Khobragade, Jiahua Fan, Franco Rupcich, Dominic J. Crotty, Taly Gilat Schmidt

Biomedical Engineering Faculty Research and Publications

Purpose

Evaluation of noise texture information in CT images is important for assessing image quality. Noise texture is often quantified by the noise power spectrum (NPS), which requires numerous image realizations to estimate. This study evaluated fractal dimension for quantifying noise texture as a scalar metric that can potentially be estimated using one image realization.

Methods

The American College of Radiology CT accreditation phantom (ACR) was scanned on a clinical scanner (Discovery CT750, GE Healthcare) at 120 kV and 25 and 90 mAs. Images were reconstructed using filtered back projection (FBP/ASIR 0%) with varying reconstruction kernels: Soft, Standard, Detail, Chest, …

A Biomechanical Simulation Of Musculoskeletal Kinematics During Ambulation, Alex Thomas

Master's Theses (2009 -)

The purpose of this study was to validate a 3D musculoskeletal model in OpenSim and assess OpenSim’s ability to determine muscle-length variation during ambulation. An 18 camera motion capture system was used to analyze 20 healthy individuals between the ages of 18 and 35. Following data collection, the data was processed through OpenSim and Visual3D. The kinematic output processed through the OpenSim model was then compared to the kinematic output of the validated Visual3D model to validate the OpenSim model. Muscle fiber length data obtained from the same experimental data was compared to control data to assess OpenSim’s muscle analysis …

Control Design And Implementation Of An Active Transtibial Prosthesis, Joseph Klein

Master's Theses (2009 -)

Prior work at Marquette University developed the Marquette Prosthesis, an active transtibial prosthesis that utilized a torsional spring and a four-bar mechanism. The controls for the Marquette Prosthesis implemented a finite state control algorithm to determine the state of gait of the amputee along with two lower level controllers, a PI moment controller to control the moment during stance and a PID position controller to control the position during stance. The Marquette Prosthesis was successful in mimicking the gait profile presented by Winter. However, after completing human subject testing, the Marquette Prosthesis was insufficient in trying to match the gait …

Will The Real Designer Please Stand Up? [Senior Design], Jay R. Goldberg

Biomedical Engineering Faculty Research and Publications

In the 1950s and 1960s, there was a popular television show called To Tell the Truth, on which three contestants claimed to be a person with an unusual occupation or distinction. Two of them were impostors, and the other was telling the truth. Four panelists asked the contestants questions to determine who was being truthful. After each panelist chose the contestant he or she thought was telling the truth, the host would ask "Will the real _____ please stand up?" To create drama, each contestant would rise at different times and then sit, leaving the contestant with the unusual occupation …

Effects Of Spinal Fusion For Idiopathic Scoliosis On Lower Body Kinematics During Gait, Karen M. Kruger, Christina R. Garman, Joseph J. Krzak, Adam Graf, Sahar Hassani, Sergey Tarima, Peter F. Sturm, Kim W. Hammerberg, Purnendu Gupta, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Objectives

The purpose of this study was to compare gait among patients with scoliosis undergoing posterior spinal fusion and instrumentation (PSFI) to typically developing subjects and determine if the location of the lowest instrumented vertebra impacted results.

Summary of Background Data

PSFI is the standard of care for correcting spine deformities, allowing the preservation of body equilibrium while maintaining as many mobile spinal segments as possible. The effect of surgery on joint motion distal to the spine must also be considered. Very few studies have addressed the effect of PSFI on activities such as walking and even fewer address …

Posterior Cervical Spine Crisscross Fixation: Biomechanical Evaluation, Joseph F. Cusick, Frank A. Pintar, Joseph S. Cheng, Jason I. Lifshutz, Narayan Yoganandan

Biomedical Engineering Faculty Research and Publications

Background

Biomechanical/anatomic limitations may limit the successful implantation, maintenance, and risk acceptance of posterior cervical plate/rod fixation for one stage decompression-fusion. A method of posterior fixation (crisscross) that resolves biomechanical deficiencies of previous facet wiring techniques and not reliant upon screw implantation has been devised. The biomechanical performance of the new method of facet fixation was compared to the traditional lateral mass plate/screw fixation method.

Methods

Thirteen human cadaver spine segments (C2-T1) were tested under flexion-compression loading and four were evaluated additionally under pure-moment load. Preparations were evaluated in a sequence of surgical alterations with intact, laminectomy, lateral mass plate/screw …

Diffusion Tensor Imaging In A Large Longitudinal Series Of Patients With Cervical Spondylotic Myelopathy Correlated With Long-Term Functional Outcome, Avinash Rao, Hesham Soliman, Mayank Kaushal, Olesya Motovylyak, Aditya Vedantam, Matthew D. Budde, Brian D. Schmit, Marjorie C. Wang, Shekar N. Kurpad

Biomedical Engineering Faculty Research and Publications

BACKGROUND

Fractional anisotropy (FA) of the high cervical cord correlates with upper limb function in acute cervical cord injury. We investigated the correlation between preoperative FA at the level of maximal compression and functional recovery in a group of patients after decompressive surgery for cervical spondylotic myelopathy (CSM).

OBJECTIVE

To determine the usefulness of FA as a biomarker for severity of CSM and as a prognostic biomarker for improvement after surgery.

METHODS

Patients received diffusion tensor imaging (DTI) scans preoperatively. FA values of the whole cord cross-section at the level of maximal compression and upper cervical cord (C1-2) were calculated. …

Promoting Global Clinical Care And Research For Children With Orthopaedic Disabilities Through Motion Analysis Technology, Jacob R. Rammer, Joycie Eulah Abiera, Monica Arroyo, Luis Fernando Caicedo, Karl Canseco, Christopher Constantino, Filipe Haces Garcia, Jorge Gomez, Nikhil T. Kurapati, Mariano Gonzalez Lugo, Terence Miller, Wilfredo Agredo Rodriguez, Carlo Emmanuel Sumpaico, Gerald F. Harris

Biomedical Engineering Faculty Research and Publications

Human motion analysis is a tool used to understand orthopaedic disabilities in children and to plan and monitor treatment strategies. It enables clinicians to quantitatively describe rehabilitative progress, plan surgeries, and conduct research. While this technology is prevalent in major academic medical centers, access is lacking in many regions throughout the world. This paper presents a novel approach to offer more accessible technology at greatly reduced cost. Current applications are underway in the Philippines, Mexico, and Colombia. Through international partnerships, improvements in clinical care, medical education, and research have been observed.

Stepping Responses To Treadmill Perturbations Vary With Severity Of Motor Deficits In Human Sci, Virginia W. T. Chu, T. George Hornby, Brian D. Schmit

Biomedical Engineering Faculty Research and Publications

In this study, we investigated the responses to tread perturbations during human stepping on a treadmill. Our approach was to test the effects of perturbations to a single leg using a split-belt treadmill in healthy participants and in participants with varying severity of spinal cord injury (SCI). We recruited 11 people with incomplete SCI and 5 noninjured participants. As participants walked on an instrumented treadmill, the belt on one side was stopped or accelerated briefly during mid to late stance. A majority of participants initiated an unnecessary swing when the treadmill was stopped in mid stance, although the likelihood of …

Tactile-Star: A Novel Tactile Stimulator And Recorder System For Evaluating And Improving Tactile Perception, Giulia Ballardini, Giorgio Carlini, Robert A. Scheidt, Ilana Nisky, Maura Casadio

Biomedical Engineering Faculty Research and Publications

Many neurological diseases impair the motor and somatosensory systems. While several different technologies are used in clinical practice to assess and improve motor functions, somatosensation is evaluated subjectively with qualitative clinical scales. Treatment of somatosensory deficits has received limited attention. To bridge the gap between the assessment and training of motor vs. somatosensory abilities, we designed, developed, and tested a novel, low-cost, two-component (bimanual) mechatronic system targeting tactile somatosensation: the Tactile-STAR—a tactile stimulator and recorder. The stimulator is an actuated pantograph structure driven by two servomotors, with an end-effector covered by a rubber material that can apply two different …

Pharmacokinetic Modeling Of 99mtc-Hmpao Images Of Isolated Perfused Rat Lungs, Katherine C. Barry

Master's Theses (2009 -)

The single-photon emission tomography (SPECT) imaging biomarker technetium-labeled hexamethylpropyleneamine oxime (99mTc-HMPAO) exists in two forms, the oxidized, cell-permeable form and the reduced, cell-impermeable form. Recent studies revealed that the lung uptake of 99mTc-HMPAO increases early in rat models of human acute lung injury. Lung uptake of 99mTc-HMPAO is the net result of multiple cellular and vascular processes, many of which can vary with acute illness. Thus, when a change in the lung uptake of 99mTc-HMPAO is detected, it is unclear how much of this change is due to alteration in the activity of the targeted cellular process versus alteration of …