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Chen, LinMEASUREMENTS OF AUTOCORRELATION FUNCTIONS USING A COMBINATION OF INTRA- AND INTER-PULSES
Master of Science, Miami University, 2015, Computational Science and Engineering
Incoherent scatter radar (ISR) is a versatile tool to study the ionosphere by measuring the autocorrelation function (ACF). Accurate ACF in the E-region is difficult to obtain because the relative short range limits the length of a pulse. The short correlation time of the ionosphere renders the correlation using the pulse-to-pulse technique useless. In the thesis, we study a method that combines intra-pulse and inter-pulse techniques and apply it to the data taken at Arecibo Observatory. We show simultaneously measured ACF’s at short and long lags and summarize the merits of ACF. Applications of ACF and its advantages are discussed. The technique used here will make the derivation of ionosphere parameters more accurate.

Committee:

Qihou Zhou (Advisor); Chi-Hao Cheng (Committee Member); Dmitriy Garmatyuk (Committee Member)

Subjects:

Aeronomy; Aerospace Engineering; Computer Engineering; Computer Science; Earth; Radiology

Keywords:

Incoherent scatter radar; ionosphere; E-region; parameters; autocorrelation function; accurate

Spaw, Alexandra J.Fetal Developmental Anatomy of the Human Cardiovascular and Central Nervous Systems Using Lugol’s Iodine Staining and Micro-Computed Tomography
Bachelor of Science (BS), Ohio University, 2014, Biological Sciences
Iodine staining with Lugol’s solution is a fast-developing technique that is revolutionizing imaging studies, because it provides the opportunity to distinguish between soft tissues through soaking of the specimen followed by computed tomography (CT scanning). Earlier protocols that resulted in marked tissue shrinkage have been modified by treating specimens with a buffered sucrose solution prior to staining with isotonic Lugol’s, yielding excellent results. This technique was used to compare the cardiovascular and central nervous systems of a series of human fetal specimens ranging in age from six weeks to 28 weeks. For this study, four specimens were analyzed that were initially labeled six weeks, 10-12 weeks, 12-14 weeks, and 16 weeks; the justification for these ages were unknown, and new gestational ages were estimated using multiple measures resulting in new age estimates of 8.5 weeks, 12.5 weeks, 13 weeks, and 15 weeks. Specimens were microCT scanned prior to soaking in Lugol’s iodine and then rescanned after soaking to compare size-related parameters and soft-tissue resolution. Anatomical structures were analyzed and segmented using the computer program Avizo, providing the basis for the generation of labeled images, 3D reconstructions, 3D interactive PDFs, movies, and other forms of digital representations of the information provided in the CT scan data. Results include all representations which lead to a catalog of developing anatomy from the late embryonic stage well into the fetal stage of gestation. The specimens analyzed showed mostly normal anatomy for their respective ages and demonstrate fetal landmarks of the organ systems in focus (e.g., ductus arteriosus, foramen ovale, and spinal cords extending farther caudally than in neonates or adults). However, the youngest specimen (8.5 weeks) demonstrated a suspected anomaly which appears to be a schizencephaly, possibly revealing the cause of death. The catalog created provides students and educators with multiple forms of media to study the fetal anatomy of these two systems and allows professionals to better visualize and interact with the reconstructed versions of key organ systems. The study of both normal and teratological anatomy will lead to greater knowledge of any defects and could potentially lead to improved treatment and surgical plans.

Committee:

Lawrence Witmer, PhD (Advisor)

Subjects:

Anatomy and Physiology; Biomedical Research; Developmental Biology; Medical Imaging; Radiology; Scientific Imaging

Keywords:

developmental anatomy; Lugols iodine; fetal anatomy; birth defects; anatomy education; micro-CT scanning;

MARTIN, ROBERT SPENCERBENCHMARKING IN RADIATION ONCOLOGY: DISCOVERING INCONSISTENCIES IN REPORTING METHODOLOGIES
MS, University of Cincinnati, 2004, Design, Architecture, Art, and Planning : Health Planning
The objective of this study is to determine if inconsistencies existed in the reporting methodologies of participants in the Mecon-PEERx survey for the University Health System Consortium (UHC) radiation oncology departments and to make recommendations that would serve to clarify appropriate benchmark indicators. Data on reporting costs for equipment repair, brachytherapy sources, medical supplies, and staffing was obtained through a questionnaire that was sent to forty-one UHC participants in the Mecon-PEERx survey. Results show statistically significant differences in the composition of several of the cost elements. This indicates that the data appearing in side-by-side reports could be compared more readily if Mecon's reporting standards in certain categories were clarified. I recommend the incorporation of additional fields and questions into the existing survey. Additional, in-depth process questions need to be asked of our benchmark partners to uncover best practices.

Committee:

Christopher Auffrey (Advisor)

Subjects:

Health Sciences, Radiology

Keywords:

Benchmarking in Radiation Oncology

Walton, Dean R.Effect of Slit Scan Imaging Techniques on Image Quality in Radiotherapy Electronic Portal Imaging
Master of Science in Biomedical Sciences (MSBS), University of Toledo, 2008, College of Graduate Studies
This research effort focused on the application of the slit scan technique in improving image quality of teletherapy portal imaging for various imaging geometries. The primary result of this study was the validation that slit scan digital radiography improves the quality of a portal image by scatter reduction resulting from the patient and machine. This method provides the ability to maintain image quality independent of patient size and air gap.The performance of the slit scan technique was evaluated by simulating a variety of imaging geometries to determine where it would have the greatest benefit on image quality when used clinically. The factors assessed that would demonstrate the effectiveness of this method on image quality were: 1. Energy response of the EPID. 2. Portal image field size. 3. Patient thickness. 4. Air gap. 5. Slit scan width. The effect on the scatter-to-primary ratio relative to valves of the above physical properties was analyzed. The results revealed that the slit scan technique was successful in eliminating scatter radiation for various imaging geometries and are beneficial where large field sizes and short air gaps maybe clinically used. Investigation into the energy response of the EPID detector confirmed published work that there is an increased sensitivity to lower energies. Due to this physical characteristic the effect of scatter radiation on degrading image quality is amplified. Scatter contribution is relatively minor in small field sizes and large air gaps. Clinically though, it is desirable to visualize anatomical landmarks to determine proper patient position requiring larger field sizes. As demonstrated in this work, when a large field size is used scatter is increased. Decreasing the air gap is necessary for large patients in order to minimize magnification. The development of higher resolution detector systems may also lead to the use of smaller air gaps in order to minimize the loss of resolution due to geometric blurring of the focal spot. In situations where the air gap is decreased scatter radiation will have an adverse effect on image contrast. The use of slit scan imaging may be of particular benefit for the improvement of large field contrast applications where reduced air gap distances are advantageous.

Committee:

Michael Dennis, PhD (Committee Chair); E. Ishmael Parsai, PhD (Committee Member); John Feldmeier, DO (Committee Member)

Subjects:

Biophysics; Optics; Radiology

Keywords:

Electronic Portal Imaging; Image Quality; Scatter Radiation; Scatter Reduction; Electronic Collimation; Megavoltage Imaging

Bluestein, Katharine T.Inversion Recovery Sequences for the Detection of Cortical Lesions in Multiple Sclerosis Using a 7 Tesla MR Imaging System
Doctor of Philosophy, The Ohio State University, 2012, Biomedical Engineering

Although white matter lesions have been the target of a majority of research in multiple sclerosis imaging, they have been shown to have little correlation to the symptoms that multiple sclerosis patients experience as the disease progresses. Due to their small size and low tissue contrast in images, cortical lesions have only recently been implicated in the disease process and have been shown to be numerous in the later stages of disease.

This work uses ultrahigh field 7 Tesla MRI capable of high image resolution and greater tissue contrast to develop an imaging protocol for cortical lesion detection in vivo. Using an inversion recovery turbo field echo sequence, white matter attenuation is shown to provide good cortical lesion and excellent white matter lesion detection. Other inversion recovery contrast options are explored as well.

Related topics are discussed, such as the contributions to the logistic regression model for lesion detection, the process for training new readers in cortical lesion detection, and finally, a novel use of the gray matter attenuated inversion recovery contrast option is shown to potentially provide insight on the severity of tissue destruction in white matter lesions. With these project components, inversion recovery is optimized for cortical lesion detecion at 7 Tesla to improve disease diagnostics and treatment monitoring.

Committee:

Petra Schmalbrock (Advisor); Bradley Clymer (Committee Member); Michael Knopp (Committee Member)

Subjects:

Radiology

Keywords:

multiple sclerosis; cortical lesions; white matter lesions; MRI; 7 Tesla

Krupka, Tianyi M.DESIGN OF CONTROLLED AND TARGETED THERMAL SENSITIZER FOR ENHANCING RADIOFREQUENCY ABLATION
Doctor of Philosophy, Case Western Reserve University, 2010, Biomedical Engineering
Focal heat ablation, in the form of radiofrequency, microwave, laser and high intensity ultrasound, is a minimally invasive outpatient procedure used in treatment of surgically inaccessible tumors. Although these treatments have produced promising outcomes, they are still in need of refinement due to local tumor recurrence caused by insufficient heating of the tumor tissue. While adjuvant or repeated treatment can be an option, it contradicts the minimally invasive nature of these procedures and may be less effective due to the development of thermal tolerance or multidrug resistance of tumor cells. Pluronic, a family of triblock copolymer of ethylene oxide-co-propylene oxide-coethylene oxide has been shown to sensitize cancer cells to chemotherapy through means of depleting intracellular ATP, inhibiting P-glycoprotein and multidrug resistant proteins. In this work, we designed and implemented a strategy that addresses insufficient tumor heating by using Pluronic as a sensitizer to reduce the lethal threshold temperature in cancer cells. Our results have demonstrated that: 1) Pluronics are effective in sensitizing cancer cells to sublethal heat injury both in vitro and in vivo; 2) while the mechanism of thermosensitization is very likely to be multifaceted, it is partially related to the inhibition of heat shock protein expression and lipid turnover rates; 3) the thermal sensitizing potency of Pluronic is dependent on its structure such as hydrophobic propylene oxide length and molecular weight; 4) biological activity of Pluronic is dependent on exposure time and dose, and can result in associated toxicities at long exposure durations and high concentrations. To prevent any potential adverse effects, the treatment regimen underwent a second iteration of engineering. In this iteration, stable and echogenic lipid shelled nanobubbles (ultrasound contrast agent) were designed, formulated and characterized (both in vitro and in vivo) to provide controlled and targeted release of Pluronic to tumors to enhance hyperthermia cancer treatment. Compared to free Pluronic, we hypothesized that the nanobubble delivery system would provide increased local dose, imaging evaluation, and potentially on-demand and targeted delivery of Pluronic, hence ensuring an efficient sensitization of cancer cells to focal hyperthermia therapy.

Committee:

James Basilion, PhD (Committee Chair); Agata Exner, PhD (Advisor); Roger Marchant, PhD (Committee Member); Ruth Keri, PhD (Committee Member)

Subjects:

Biomedical Research; Oncology; Radiology

Keywords:

Pluronic; L61; Tumor; P85; ABLATION; Hyperthermia; DHD/K12/TRb

Larry, Fout TylerComparison of Magnetic Resonance Imaging & Sonography in an Animal Model in the Acute Stages of Carpal Tunnel Syndrome
Master of Science, The Ohio State University, 2013, Allied Medical Professions
Carpal Tunnel Syndrome (CTS) is a musculoskeletal disorder characterized by the compression of an enlarged or inflamed median nerve as it passes through the carpal tunnel and deep to the flexor retinaculum. CTS is one of the most common entrapment syndromes of the upper limbs, with hundreds of thousands of new cases of CTS reported by the Centers for Disease Control and Prevention in the United States every year (CDC,2012). Presently, according to the ACR Appropriateness Criteria, Magnetic Resonance Imaging (MRI) has a rating of nine out of ten as the best choice for diagnosing CTS in patients with persistent wrist pain after the initial radiograph. The Appropriateness Criteria also lists musculoskeletal (MSK) sonography with a rating of one out of ten; however, qualities such as accessibility, cost effectiveness, being less invasive, relatively painless, time effectiveness, as well as providing real time imaging, may provide additional information in conjunction with Magnetic Resonance. The purpose of this study was to evaluate the significance, if any, through quantitative analysis of the median nerve, between Magnetic Resonance and Sonography in the acute stages of CTS. Imaging was performed on Maccaca fascularis monkeys at baseline, working, and recovery intervals. The data was collected from two independent, blinded researchers, one certified in Magnetic Resonance, the other certified in Sonography. Although each study demonstrated no conclusive comparison between MRI and Sonography in the evaluation of the median nerve, the information gained regarding study protocol is invaluable to provide feedback to design a higher level clinical study. MSK sonography may be a useful tool in combination with MRI, to diagnose CTS, with minimal discomfort to the patient. More research needs to be conducted in the acute stages of CTS before the patient reaches the advanced, symptomatic stages, in the form of a clinical human study.

Committee:

Kevin Evans (Advisor)

Subjects:

Radiology

Keywords:

MMN; Carpal tunnel syndrome; Median nerve; MRI; SNR; CEUS

Vogt, Keith M.Optimization of physiologic noise correction in functional magnetic resonance imaging
Doctor of Philosophy, The Ohio State University, 2009, Biomedical Engineering

Though in widespread clinical and research use as a tool to evaluate brain function, functional magnetic resonance imaging (FMRI) data is severely contaminated by noise, due in large part to physiologic noise caused by respiratory and cardiac variations over time. This dissertation attempts to better characterize several physiologic noise correction techniques applied to pain FMRI data. Three studies are described that collectively work toward determining an optimal physiologic noise correction algorithm to be used in future pain FMRI studies.

First, a novel algorithm, RetroSLICE, is described that uses linear regression to correct acquired images for signal intensity fluctuations correlated to measured respiratory, cardiac, and capnometry variations. The impact of this technique was assessed for a 1.5 T pain FMRI experiment. Each physiologic noise regressor used as a part of the RetroSLICE algorithm independently resulted in a decrease in timecourse variance and an improvement in model fit. Combined correction for the instantaneous effects of respiratory and cardiac variations caused a 5.4% decrease in signal variance and increased model fit (mean R2a) by 65%. The addition of ETCO2 correction as part of the general linear model led to 39% further improvement in model fit. Each of these corrections also caused changes in the group activation map.

Next, an optimal transfer function between ETCO2 level and BOLD signal changes was empirically determined using FMRI data in which paced breathing forced a 35% decrease in ETCO2. ETCO2 data convolved with this optimized response function was compared to another measure, the respiratory volume over time (RVT) convolved with an optimized respiration response function. When regressed against FMRI data collected during a breathing modulation task, ETCO2 was more strongly and diffusely correlated to the data than RVT. Conversely, when the same comparative analysis was performed on pain FMRI data, RVT was more strongly correlated than ETCO2. In both cases, allowing ± 2 s flexibility in the response function peak times did not change the relative correlation to the MR data of the ETCO2 compared to the RVT timecourses.

Finally, the well-known physiologic noise correction algorithm, RETROICOR, was implemented on pain FMRI data collected at 1.5 and 3.0 T. Respiratory and cardiac correction with Fourier series phase fitting caused an 8.2% decrease in signal variance and a 227% increase in model fit at 1.5 T, indicating performance superior to RetroSLICE. At 3.0 T, significantly greater improvements were seen: a 10.4% decrease in signal noise and 240% increase in mean R2a. ETCO2 correction applied with the optimized response function previously determined caused insignificant changes in noise reduction and model fit. Further exploration of the properties of the RETROICOR algorithm showed no difference in impact when applied with physiologic input data sampled at a much higher rate or when accounting for the interleaved slice acquisition order. These findings suggest that RETROICOR should be included as a part of the physiologic noise correction procedure in pain FMRI studies at 1.5 and 3.0 T.

Committee:

Petra Schmalbrock, PhD (Advisor); Robert Small, MD (Committee Chair); Cynthia Roberts, PhD (Committee Member); Alan Litsky, MD,ScD (Committee Member)

Subjects:

Engineering; Radiology; Scientific Imaging

Keywords:

functional MRI; brain; pain; physiologic noise correction; RETROICOR; RetroSLICE; ETCO2

Paschal, Cynthia BruceThree-dimensional high-resolution magnetic resonance imaging of the coronary arteries
Doctor of Philosophy, Case Western Reserve University, 1992, Biomedical Engineering
Coronary heart disease is a life-threatening illness which is the leading cause of death in the U.S. Improved methods for early detection and monitoring of coronary heart disease are needed in the battle against this killer. Thus, the objective of this dissertation research was to develop and evaluate a non-invasive, three dimensional magnetic resonance imaging technique capable of visualizing the coronary arteries. The greatest challenge towards meeting this goal is respiratory motion of the heart. This motion was characterized and found to be on the order of tens of millimeters in range and greater in extent along the cranio/caudal axis than along the anterior/posterior axis for a supine subject. The motion was determined to be more complex than a simple one dimensional translation. Several methods to compensate for respiratory motion were evaluated via examination of point spread functions, computer simulations of imaging, and actual application to imaging experiments. A 3D approach was selected for its ability to provide high resolution, high signal-to-noise ratio images. The implementation of a 3D technique for cardiac imaging imposes a variety of filters over the detected signal. These filters were simulated and analyzed for their effect on contrast and resolution. Finally, the developed technique was used on normal volunteers and patients with known pathology. The technique was very successful in depicting anatomy in normal volunteers. The technique was able to clearly reveal pathology in some patients yet yielded false negatives in others. The inconsistencies in the ability to reveal pathology may actually have been related to different types of disease. If so, then the technique may provide a method of discrimination between different types of disease though more experimentation is needed to characterize the appearance of pathology in this 3D technique. In addition, improving the technique by incorporating more respiratory compensation, especially gating, increasing resolution, including spatially and/or frequency selective RF pulses, employing appropriate surface coils, and possibly utilizing contrast agents should increase the diagnostic capability of 3D MRI of the coronary arteries

Committee:

Mark Haacke (Advisor)

Subjects:

Health Sciences, Radiology

Keywords:

Coronary heart disease; Coronary arteries; Magnetic resonance imaging

De Silva, Weeraddana Manjula KumaraCorrelation Imaging for Real-time Cardiac MRI
PhD, University of Cincinnati, 2016, Arts and Sciences: Physics
Cardiac magnetic resonance imaging (MRI) suffers from artifacts arising from respiration, heartbeat and blood flow. There are several existing MRI techniques that address these issues by speeding up the MR image acquisition. Two parallel imaging techniques, SENSE and GRAPPA, are standard procedures in clinical MRI. A recently developed high-speed MR imaging technique, correlation imaging, has the potential to overcome imaging speed limitation of SENSE and GRAPPA, thereby providing a better approach to accelerating cardiac MRI for reduced motion artifacts. The presented work in this thesis aims to develop a new correlation imaging approach to achieving this speed gain using outer k-space data sparsity and demonstrate this new approach in cardiac MRI. Correlation imaging converts image reconstruction into the estimate of correlation functions. Correlation functions may arise from coil sensitivity or image-space sparsity. Because outer k-space data have higher image-space sparsity than the center k-space data, outer k-space data are more correlated than the center k-space data. By translating outer k-space data sparsity and the coil sensitivity encoding into k-space variant correlation functions, correlation imaging provides a speed gain over SENSE and GRAPPA that rely only on coil sensitivity encoding. Free breathing cardiac imaging experiments have been conducted to test our new approach. Compared to SENSE- and GRAPPA-based approaches, correlation imaging gives higher spatial resolution in free breathing cardiac black-blood imaging and better temporal resolution in free breathing real-time cardiac CINE imaging. It is demonstrated that correlation imaging with k-space variant correlation functions can overcome the speed limitations in the parallel imaging and offers the capability of real-time cardiac imaging.

Committee:

Yu Li, Ph.D (Committee Chair); F Paul Esposito, Ph.D. (Committee Member); David Mast, Ph.D. (Committee Member); Janaka Wansapura, Ph.D. (Committee Member); L.C.R. Wijewardhana, Ph.D. (Committee Member)

Subjects:

Radiology

Keywords:

Correlation imaging;Correlation function;High-speed MRI;Parallel imaging;Real-time imaging;Cardiac CINE imaging

Ginsburg, ShoshanaMachine-Based Interpretation and Classification of Image-Derived Features: Applications in Digital Pathology and Multi-Parametric MRI of Prostate Cancer
Doctor of Philosophy, Case Western Reserve University, 2016, Biomedical Engineering
The analysis of medical images--from magnetic resonance imaging (MRI) to digital pathology--for disease characterization typically involves extraction of hundreds of features, which may be used to predict disease presence, aggressiveness, or outcome. Unfortunately, the dimensionality of the feature space poses a formidable challenge to the construction of robust classifiers for predicting disease presence and aggressiveness. In this work we present novel strategies to facilitate the construction of robust, interpretable classifiers when the dimensionality of the feature space is high. In the context of prostate cancer, we demonstrate the benefit of our approach for identifying (a) radiomic features that are useful for detecting prostate cancer on multi-parametric MRI, (b) radiomic features that predict the risk of prostate cancer recurrence on T2-weighted MRI, and (c) histomorphometric features describing cellular and glandular architecture on digital pathology images that predict the risk of prostate cancer recurrence post-treatment. In the context of breast cancer, we identify histomorphometric features describing cancer patterns in estrogen receptor positive (ER+) breast cancer tissue slides that can predict (a) which cancer patients will have recurrence following treatment with tamoxifen and (b) risk category as determined by a 21 gene expression assay called Oncotype DX. Additionally, we also investigate whether radiomic features characterizing prostate tumors that manifest in the peripheral zone of the prostate are different from radiomic features characterizing transition zone tumors, and we develop a novel approach for pharmacokinetic modeling on dynamic contrast-enhanced MRI that relies exclusively on prostate voxels, with no reliance on an arterial input function or reference tissue.

Committee:

Anant Madabhushi (Advisor)

Subjects:

Biomedical Engineering; Medical Imaging; Radiology

Keywords:

Prostate cancer; MRI; computer-aided diagnosis; dimensionality reduction

Wang, YingyingIntegration of fMRI and MEG towards modeling language networks in the brain
PhD, University of Cincinnati, 2013, Engineering and Applied Science: Biomedical Engineering
Human language is a complex neurocognitive process that relies upon a widely-distributed network in the brain. With the advent of advanced neuroimaging techniques (i.e. fMRI and EEG/MEG), our understanding of language system is being transformed from functional segregation to functional integration over the last decade. Instead of asking "where" and "when" the task-related brain activity happened, researchers start to ask how the brain networks are modulated by the task. The main goal of this dissertation work is to elucidate language networks by integrating fMRI from a group of children who have participated annually in a longitudinal study from their childhood through adolescence and MEG data from the same group of children. This dissertation consists of four main parts: (1) Neuroimaging data from each modality were analyzed separately and spatial maps were quantitatively compared. This is the initial step establishing a framework to integrate the two modalities, because it would provide confidence that fMRI could be used as spatial priors on MEG source localization. (2) Functional network connectivity supporting narrative comprehension was established using fMRI data only from two versions of the narrative comprehension task. FMRI provides us with the spatial information of the underlying network architecture supporting narrative comprehension. However, it is unclear that how the underlying mechanism of high-order cognitive processes modulates the brain networks during narrative comprehension task. Therefore, (3) in order to improve our understanding of these high-order cognitive processes, we integrated fMRI and MEG data within a Bayesian framework by applying a Multiple Sparse Prior (MSP) algorithm from Friston et al. 2008. Both simulated data and experimental data were examined. For experimental data, the group fMRI results were used as spatial priors in the MEG source reconstruction. As a result, we obtained fine spatiotemporal time courses from multiple elements of the brain-language networks. This step enables us to capitalize on the advantages of each modality and obviate the primary limitations of each, leading to an improved method for elaborating the complex network structure of language processing in the human brain. (4) Finally, we used Dynamic Causal Modeling (DCM), a recent network analysis technique, to study the fine spatiotemporal time courses from (3) in order to improve our understanding of how high-order cognitive processes modulate the pathways within the network architecture. This dissertation makes several significant contributions to the neuroimaging field for better understanding of language networks. First, this is a first cross-modality validation study that qualitatively and quantitatively compares the fMRI and MEG data from the same subjects performing the same high-order cognitive tasks. Second, fMRI spatial maps were successfully incorporated into MEG inverse problem using MSP algorithm under a hierarchical Bayesian framework. Using both simulated data and experimental data, we provided evidence of improvements in the MEG source reconstruction by incorporating spatial priors. Finally, by using fine spatiotemporal time courses from functional active regions, we expanded our understanding of the language networks previously established from our fMRI data alone and found pathways within the language networks supporting narrative comprehension.

Committee:

Scott Holland, Ph.D. (Committee Chair); Christy Holland, Ph.D. (Committee Member); Jaroslaw Meller, Ph.D. (Committee Member); Weihong Yuan, Ph.D. (Committee Member)

Subjects:

Radiology

Keywords:

Bayesian statistics;fMRI;MEG;language networks;integration;adolescent

Copley, StaceyAssessment of Instructor Information Technology Self-efficacy on Online Course Delivery Modes and Design Methods in the Radiologic Sciences
Master of Science, The Ohio State University, 2012, Allied Medical Professions

Introduction

The purpose of this study was to determine the current status of online education in the radiologic sciences, as well as the use of online educational tools, methods of delivery, and the instructor IT self-efficacy. This study provides information about the tools currently utilized in online education in the radiologic sciences as well as to provide information regarding information self-efficacy from the instructors’ perspectives.

Methods

An electronic survey instrument was created using Survey Monkey®, and invitations were sent to a random stratified sample of 365 educators, including instructors from Joint Review Committee accredited programs in radiography, radiation therapy, and nuclear medicine. Of these 365 invitees, 102 participants responded to the survey resulting in a 27.95% response rate. Of the 102 respondents to this survey, only 38 educators indicated they offer on-line courses. The survey results were then analyzed descriptive statistics, frequency values, and Spearman Rho correlation.

Results

Approximately two-thirds of the programs responding to the survey did not offer online core courses. However the institutions that do provide online core radiologic courses, most commonly reported using PowerPoint® and Flash® online tools for course delivery and BlackBoard® was reported as the most commonly used learning management system. Results from the survey demonstrated a significant relationship between the type of institution and the use of synchronous technologies suggesting that university-based programs were more likely to utilize this technology. Significant relationships were not identified for the remaining variables: IT self-efficacy and the instructors, age, years of teaching in higher education, years of teaching online, the use of asynchronous technologies or the use of synchronous technologies. Additionally, no significant relationship exists between the type of institution and the use of asynchronous technologies.

Conclusion

The utilization of the online education in the radiologic sciences has increased, but the traditional classroom setting is still the primary class style offering. PowerPoint remains the primary content delivery tool of choice, suggesting a need for educators to incorporate tools that promote student interactions and interactive learning. The results from the survey did not reveal a significant relationship between IT self efficacy and age, years of teaching, years of teaching online course and the use of synchronous and asynchronous technologies, but the small correlations identified suggests that the younger instructors have a higher IT self-efficacy. Additionally, no significant relationship exists between the type of institution and the use of asynchronous technologies. However, there is a significant relationship between the type of institution and the use of synchronous technologies. According to the literature, the demonstrated small negative correlations may indicate that a relationship exists if studies in a larger sample.

Committee:

Nina Kowalczyk, PhD (Advisor); Susan White, PhD (Committee Member); Georgianna Sergakis, PhD (Committee Member)

Subjects:

Education; Educational Software; Educational Technology; Radiology

Keywords:

Distance education; radiologic sciences; Information Technology Self Efficacy; learning management systems; radiologic instructors

Scherl-Slusher, Alice I.Screening Mamography: A Comparison Between US and Australian Healthcare Delivery
Master of Health and Human Services, Youngstown State University, 2000, Department of Health Professions
US and Australian women's experiences with screening mammography were studied with regard to helathcare delivery systems: the Australian government provides free screening, the US does not. Methods: Self-report surveys concerning mammography experience were administered to 402 Australian and 381 US women having mammograms on mobile facilities. Results: There were no differences in compliance with mammography guidelines. US women had significantly more knowledge about breast cancer risks. Seeing the mobile facility and receiving a reminder were important cues to action for Austrailians, having a doctor's recommendation was more important for US women. Most Australian women would continue screening if they had to pay for it; most US women said they would be more likely to be compliant if mammography were free.

Committee:

Carolyn Mikanowicz (Advisor)

Subjects:

Health Sciences, Radiology

Keywords:

Breast; Radiography; United States; Australia

Murad, Mark RichardRadiation View Factors Between A Disk And The Interior Of A Class Of Axisymmetric Bodies Including Converging Diverging Rocket Nozzles
Master of Science in Mechanical Engineering, Cleveland State University, 2008, Fenn College of Engineering

A general symbolic exact analytic solution is developed for the radiation view factors including shadowing by the throat between a divergence thin gas disk between the combustion chamber and the beginning of the rocket nozzle radiating energy to the interior downstream of the nozzle contour for a class of coaxial axisymmetric converging diverging rocket nozzles. The radiation view factors presented in this thesis for the projection which are blocked or shadowed through the throat radiating downstream to the contour have never been presented before in the literature.

It was found that the curvature of the function of the contour of the nozzle being either concave up or down and the slope of the first derivative being either positive or negative determined the values used for the transformation of the Stokes Theorem into terms of x, r (radius) and f(x) for the evaluation of the line integral.

The analytical solutions from the view factors of, for example, the interior of a combustion chamber, or any radiating heat source to a disk may then be applied to the solution of the view factor of the disk to the interior of the rocket nozzle contour presented here. This modular building block type approach is what the author desires to allow the development of an interstellar matter antimatter rocket engine. The gases of this type of reaction shall approach those towards the speed of light, which shall involve a transport phenomena, which the author is looking forward to researching the solution.

Committee:

Asuquo Ebiana, PhD (Advisor); Majid Rashidi, PhD (Committee Member); John Frater, PhD (Committee Member); John Oprea, PhD (Committee Member)

Subjects:

Aerospace Materials; Astrophysics; Chemical Engineering; Computer Science; Electromagnetism; Engineering; Gases; Materials Science; Mathematics; Mechanical Engineering; Nuclear Chemistry; Nuclear Physics; Radiation; Radiology; Scientific Imaging; Transportation

Keywords:

shadowing; radiation view factor; rocket nozzle: cooling; radiation heat transfer; differential geometry; configuration factor

DICK, ERIC TIMOTHYA Survey of CT Phantom Considerations for the Study of Blooming Artifacts as Observed in CT Coronary Angiography Studies: A Preliminary Study
MS, University of Cincinnati, 2008, Medicine : Radiology-Radiological Sciences (Medical Physics)
The presence of image "blooming" artifacts, in particular with respect to highly calcifiedplaques, has been a major impediment to the implementation of Multi-detector Computed Tomography (MD-CT) as an alternative to standard angiography in routine clinical practice. A beam hardening phantom system was developed to determine the dependence of blooming with respect to measured density in Hounsfield Units (HU), of 5mm diameter plaques. Custom software was developed to provide reproducible objective measurements of plaque size. Plaque diameter was measured using a series of axially distributed profiles centered on the object. Reconstruction blur was shown to be a significant, density dependent contributor to standard clinical blooming measurements. Beam hardening was shown to not affect measurements of sample diameter in a blur corrected study. Furthermore, two additional phantom designs have been proposed and evaluated for the future study of partial volume and cone beam affects on blooming.

Committee:

Lisa Lemen, PhD (Committee Chair); Elson Howard, PhD (Committee Member); Lamba Michael, PhD (Committee Member)

Subjects:

Radiation; Radiology; Scientific Imaging

Keywords:

blooming; computed tomography; artifact; CT; beam hardening; partial volume averaging;cone beam

Woods, Brent J.Computer-Aided Detection of Malignant Lesions in Dynamic Contrast Enhanced MRI Breast and Prostate Cancer Datasets
Doctor of Philosophy, The Ohio State University, 2008, Electrical and Computer Engineering

Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) is considered to have great potential in cancer diagnosis and monitoring. During the DCE-MRI procedure, repeated MRI scans are used to monitor contrast agent movement through the vascular system and into tissue. By observing the vascular permeability characteristics, radiologists can detect and classify malignant tissues. When used for diagnostic purposes, the DCE-MRI procedure often requires manual detection, classification, and marking of tumor tissues. This process can be time consuming and fatiguing especially when multiple DCE-MRI procedures must be processed to monitor the progress of a cancer therapy. Manual analysis also suffers from inter- and intra-observer variations which can lead to lesion segmentation inconsistencies.

The goal of this dissertation research is to design and develop a tool to aid radiologists, researchers, and clinicians in the detection, segmentation, and analysis of malignant lesions from DCE-MRI datasets. The diagnostic tool presented in this research is model independent, speeds analysis, and provides more consistent segmentations. The approach of the project is to apply statistical 4-D image texture analysis features along with a classifier (such as a neural network) to analyze DCE-MRI datasets.

Performance of the computer aided diagnosis (CAD) tool for this project is demonstrated with breast and prostate DCE-MRI data. Training methodology is reported so that extension to other types of cancers and anatomical regions is made possible. Results from the computer assisted diagnostic tool are compared with manual analysis performed by radiologists. The specific research aims of this dissertation are: a) provide a tool for quantitative and quick DCE-MRI analysis by providing radiologists a segmentation (for semi-automatic or automatic application), b) quantify inter- and intra-observer variations that occur during manual lesion segmentation and compare performance with computer-based segmentations, and c) explore the performance of the CAD system in different anatomic regions (including breast and prostate cancer datasets).

Committee:

Bradley Clymer, PhD (Advisor); Ashok Krishnamurthy, PhD (Committee Member); Tahsin Kurc, PhD (Committee Member)

Subjects:

Artificial Intelligence; Bioinformatics; Biomedical Research; Computer Science; Electrical Engineering; Radiology

Keywords:

Computer Aided Diagnosis; CAD; Dynamic Contrast Enhanced MRI; DCE-MRI; Medical Imaging; Neural Network

Deshmane, Anagha VishwasPartial Volume Quantification Using Magnetic Resonance Fingerprinting
Doctor of Philosophy, Case Western Reserve University, 2017, Biomedical Engineering
Magnetic resonance imaging (MRI) is a key clinical tool which allows for imaging of biological tissues with large field-of-view, millimeter resolution, and good soft tissue contrast, without exposing the patient to ionizing radiation. Magnetic Resonance Fingerprinting (MRF) is a quantitative MRI method which pairs pseudorandom magnetization excitations and fast image acquisition with dictionary-based reconstruction for simultaneous mapping of multiple tissue and experimental properties, including T1, T2, and off-resonance, from a single experiment performed within a clinically feasible scan time. MRF signal evolutions vary in shape for different combinations of encoded properties. Like other quantitative MRI methods, MRF maps yield quantitative maps in which properties are averaged over the voxel dimensions. However, in the presence of partial volumes, voxel-averaged properties are insufficient to quantitatively assess tissue characteristics such as the potential presence of pathology. It is therefore necessary to quantify both tissue properties and voxel composition. The uniqueness of signal evolutions emanating from different tissue types in MRF allows for both tissue property mapping as well as quantification of partial volumes from the same measurement. In this dissertation, two approaches to partial volume quantification by MR Fingerprinting (PV-MRF) are quantitatively assessed for accuracy in the presence of artifacts and model errors. Applications of PV-MRF are also explored, including segmentation of pathology, improved synthetic imaging, and absolute quantification of sub-voxel tissue species.

Committee:

Mark Griswold (Advisor); Nicole Seiberlich (Committee Chair); Xin Yu (Committee Member); Erkki Somersalo (Committee Member)

Subjects:

Biomedical Engineering; Engineering; Medical Imaging; Radiology

Keywords:

magnetic resonance imaging; quantitative imaging; partial volume; absolute quantification; proton density mapping; subvoxel analysis; tissue characterization; tissue quantification; magnetic resonance fingerprinting;

Moore, Ryan A.Virtual Implantation of Mechanical Circulatory Support Devices
MS, University of Cincinnati, 2016, Medicine: Clinical and Translational Research
Our group previously described successful use of virtual implantation of the 70cc Total Artificial Heart (TAH) to predict safe placement in small-size patients not meeting standard fit criteria. With the new 50cc TAH, there is an opportunity for broader use of the TAH device in pediatric patients with biventricular heart failure. The proposed fit criteria for the 50cc TAH (BSA 1.2-1.6 m2) has not been tested in actual patients. The study objective was to determine the efficacy of virtual implantation of the 50cc and 70cc TAH in a cohort of pediatric heart failure patients and compare virtual fit results with proposed fit criteria.

Committee:

Erin Nicole Haynes, Dr.P.H. (Committee Chair); Peace Chike Madueme, M.D. M.S. (Committee Member); Angela Lorts, M.D. (Committee Member); David Luis Simon Morales, M.D. (Committee Member); Andrew Redington, M.D. (Committee Member)

Subjects:

Radiology

Keywords:

virtual surgery;virtual implantation;total artificial heart;mechanical circulatory support;heart failure;heart transplant

Edalati Ahmadsaraei, MasoudDiffusion Tensor Imaging: Application to Cardiovascular Magnetic Resonance Imaging
PhD, University of Cincinnati, 2016, Arts and Sciences: Physics
The work presented in this thesis concentrates on how to perform in vivo cardiac diffusion tensor imaging (DTI) by using magnetic resonance imaging (MRI). Translation of this technique (DTI) to moving organs such as the beating heart has become feasible, but remains a challenging task, occasionally leading to poor MRI signal intensity and accuracy. The first chapter outlines the anatomy and physiology of the human heart, linking the structure of cardiac muscle fiber to its function during contraction and relaxation. The macroscopic properties of cardiac muscle and structure of the myocardium are further discussed in this chapter. This will provide a deeper understanding of the myocardium architecture. Chapter 2 describes the fundamental principles behind magnetic resonance imaging (MRI). The basic principles of spin properties, energy state, magnetization, and MR signal acquisition are also described in this chapter. Diffusion tensor MRI can be used to depict the anisotropy of tissue. Chapter 3 discusses the concept of diffusion tensor imaging and associated forms of motion together with their physical signi cance. Measurements of diff usion motion and their interpretation are necessarily tied to a mathematical description. Consequently, a detailed coverage of diff usion mathematical description, and diffusion signal attenuation equation are presented with the MR techniques for quantifying diffusion process. Chapter 4 explores the feasibility of in vivo DTI of the human heart with the conventional spin echo pulse sequence. Echo planar imaging (EPI) acquisition in combination with parallel imaging method enables the single-shot spin echo diffusion sequence to collect in vivo diffusion-weighted images (DWI) within a single cardiac phase. 1-D navigator technique was used as a respiratory motion compensation to obtain DWIs within an accepted window for reducing the effect of respiration. Cardiac DTI was performed on healthy and well-motivated volunteers to evaluate the technique robustness and potential. The aim of chapter 5 is to investigate the implementation of in vivo cardiac DTI using accelerated turbo spin echo (TSE) acquisition. DWIs acquired with this method displayed less geometrical variations, susceptibility, and eddy current artifacts across the myocardium of the LV. Consequently, in vivo cardiac DTI with turbo spin echo resulted in improved DWI quality and achieving more reliable quantitative diff usion metrics in myocardium.

Committee:

Michael Taylor, M.D. Ph.D. (Committee Chair); F Paul Esposito, Ph.D. (Committee Member); Scott Holland, Ph.D. (Committee Member); David Mast, Ph.D. (Committee Member)

Subjects:

Radiology

Penzias, GregoryIdentifying the Histomorphometric Basis of Predictive Radiomic Markers for Characterization of Prostate Cancer
Master of Sciences (Engineering), Case Western Reserve University, 2017, Biomedical Engineering
Radiomics has shown promise for in vivo prediction of cancer risk, thus providing a potential avenue for reducing over-treatment and unnecessarily invasive biopsy-based diagnosis. Radiomics could be particularly beneficial for stratifying patients into different risk groups in the context of prostate cancer (PCa), for which limitations of current in vivo risk assessment result in over-diagnosis and over-treatment. Despite its promise, successful translation of radiomics into the clinic may require a more comprehensive understanding of the underlying morphologic tissue characteristics they reflect. Few studies, however, have attempted to establish the biological or histomorphometric basis for the performance of radiomics. Accomplishing this requires fusing the information obtained from the imaging modalities of radiology and histopathology, since the gold standard definition of PCa comes from histopathologic analysis of whole-mount specimens. The first step in performing this radiology-pathology fusion in PCa entails achieving spatial correspondence between preoperative in vivo magnetic resonance imaging (MRI) and ex vivo hematoxylin & eosin (H&E)-stained whole-mount radical prostatectomy specimens via deformable co-registration. Co-registration, however, requires whole-mount histology sections (WMHSs), which are not always feasible to obtain. In such cases, large specimens are cut into multiple smaller tissue fragments. This thesis presents work on two related modules of radiology-pathology fusion in PCa: First, a novel automated program called AutoStitcher, which reconstructs pseudo whole-mount histology sections (PWMHSs) by digitally stitching together multiple smaller tissue fragments, thus enabling co-registration with in vivo radiographic imagery. AutoStitcher reconstructed PWMHSs with less than 3% error relative to manually stitched PWMHSs. Second, comprehensive sets of radiomic features extracted from MRI and quantitative histomorphometric features from H&E were extracted and then spatially co-localized to characterize each tumor region. Correlative analysis revealed a set of promising predictive radiomic markers that could accurately distinguish low- from intermediate-/high-risk PCa and a set of QH features that may form their histomorphometric basis. Results were validated on an independent dataset from a different institution.

Committee:

Anant Madabhushi (Advisor); Satish Viswanath (Committee Member); David Wilson (Committee Member)

Subjects:

Biomedical Engineering; Computer Science; Engineering; Medical Imaging; Oncology; Radiology

Keywords:

radiomics; quantitative histomorphometry; prostate cancer; imaging biomarkers; digital pathology; data fusion; computer vision; image reconstruction; image stitching

England, Gregory MilesEffect of Scanning Conditions on Cone Beam Computed Tomography Gray Value
Master of Science, The Ohio State University, 2016, Dentistry
Cone beam computed tomography (CBCT) produces a three-dimensional image that allows for precise diagnosis and better treatment planning of various dental complications. However, reliability of CBCT to measure bone mineral density (BMD) measurement has not fully evaluated. Thus, the objective of the current study was to examine whether the CBCT can produce the gray value distribution parameters (mean, variability, and 5 percentile low and high) and their magnitudes are influenced by different scanning conditions and scanners. ATOM Max dental and diagnostic artificial head (model 711-HN, CIRS, Norfolk, VA) was scanned by two CBCT scanners (Planmeca ProMax® 3D Mid and iCAT). Planmeca and iCAT scanners used full field of view with normal dose and ultra-low dose (ULD) sub-options for 3 scanning resolutions (200, 400, and 600 micron voxel sizes) and 4 scanning resolutions (200, 250, 300 and 400 micron voxel sizes), respectively. After 9 weeks, the artificial head was scanned again by the Planmeca scanner with the same scanning conditions. In addition, 2 hydroxyapatite phantoms (1220, and 1540 mg/cm3) were adhered on the artificial head and scanned using the normal and ULD scanning conditions of 400 micron voxel size with both scanners. The gray value histograms of each region were utilized to determine mean value (Mean), standard deviation (SD), 5th percentiles low and high (Low5 and High5) of gray values. The gray value parameters were successfully measured by the CBCT images. The different scanning conditions and the bilateral locations of the artificial head did not have significant effects on measurements of the gray value parameters (p>0.436) with excellent repeatability. However, the iCAT scanner produced significantly different gray values from the Planmeca scanner (p<0.001). These results suggested that the CBCT can measure a material density while calibration of absolute measures is necessary to obtain comparable values between different scanners.

Committee:

Do-Gyoon Kim (Advisor); Toru Deguchi (Committee Member); Allen Firestone (Committee Member); F. Michael Beck (Committee Member)

Subjects:

Dentistry; Radiology

Keywords:

Cone Beam Computed Tomography, Scan conditions, Gray values, Bone density

Mazumder, RiaEstimation of Spatiotemporal Isotropic and Anisotropic Myocardial Stiffness using Magnetic Resonance Elastography: A Study in Heart Failure
Doctor of Philosophy, The Ohio State University, 2016, Electrical and Computer Engineering
Heart failure (HF), a complex clinical syndrome that is characterized by abnormal cardiac structure and function; and has been identified as the new epidemic of the 21st century [1]. Based on the left ventricular (LV) ejection fraction (EF), HF can be classified into two broad categories: HF with reduced EF (HFrEF) and HF with preserved EF (HFpEF). Both HFrEF and HFpEF are associated with alteration in myocardial stiffness (MS), and there is an extensively rich literature to support this relation. However, t0 date, MS is not widely used in the clinics for the diagnosis of HF precisely because of the absence of a clinically efficient tool to estimate MS. Current clinical techniques used to measure MS are invasive in nature, provide global stiffness measurements and cannot assess the true intrinsic properties of the myocardium. Therefore, there is a need to non-invasively quantify MS for accurate diagnosis and prognosis of HF. In recent years, a non-invasive technique known as cardiac magnetic resonance elastography (cMRE) has been developed to estimate MS. However, most of the reported studies using cMRE have been performed on phantoms, animals and healthy volunteers and minimal literature recognizing the importance of cMRE in diagnosing disease conditions, especially with respect to HF is available. Additionally the existing cMRE techniques assume that the waves are propagating in a uniform, infinite, homogenous, isotropic medium. However, such assumptions are violated in the heart since it bears a complex anisotropic (orthotropic) geometry; current cMRE techniques may not provide the true mechanical properties of the myocardium and instead provide only an effective estimate of MS. The overall goal of this dissertation is to: i) implement the currently established cMRE technique in HF (both HFrEF and HFpEF) porcine models to validate MS as a diagnostic biomarker; ii) explore the scope of ex-vivo cardiac diffusion tensor imaging (DTI) in investigating myocardial architecture (required for anisotropic stiffness measurements) in a HF causing diseased model; iii) develop waveguide cMRE inversion (a tool to estimate anisotropic stiffness) and validate the algorithm using finite element (FE) simulations; and iv) implement waveguide cMRE inversion in a hypertensive heart model (that has the potential to trigger HFpEF) to demonstrate the feasibility of measuring anisotropic MS in HF causing disease conditions. From the results obtained it was observed that MS in a hypertensive heart (HFpEF causing condition) increased progressively with disease progression when compared to a normal heart; and this increase exhibited significant correlation with left ventricular pressure (increases due to hypertension) and thickness (increases secondary to hypertension). Additionally, MS demonstrated progressive focal increase in an infarcted myocardium (HFrEF causing condition) compared to non-infarcted remote myocardium with disease progression and the increase in MS exhibited significant correlation with i) mechanical testing-derived MS, ii) circumferential end-diastolic strain, iii) T1 values and iv) extra-cellular volume fraction. The next part of the dissertation investigates the change in cardiac geometry (essential for investigating anisotropic elastic properties) as a result of myocardial infarction (HFrEF causing condition) in formalin-fixed ex-vivo specimens using DTI. Since in-vivo DTI is very complex (due to cardiac and respiratory motion) and is still in its inception, formalin-fixed ex-vivo specimens were used for the preliminary investigation. Hence it was essential to ensure whether the alterations observed in cardiac geometry were related to pathology or if it was an effect of the fixation process. The results demonstrated that formalin-fixation did not alter the structural orientation of the fibers and that fibers in the infarcted myocardium were shorter and disarrayed. Additionally, a post processing filter was developed to reduce acquisition time in cardiac DTI, thereby assisting in faster imaging. The filter was implemented on formalin-fixed ex-vivo myocardial infarction (HFrEF causing condition) induced porcine hearts to demonstrate that the technique preserved subtle pathological alterations in myocardial structure. The last section of this dissertation validates the waveguide MRE inversion algorithm and demonstrates its feasibility in a hypertensive heart model. From the results it was observed that the inversion successfully resolved the anisotropic elastic properties of the materials in majority of the directions. The inversion failed in one shear direction because with the current actuation and geometric setting that particular mode was not being excited. Additionally, the anisotropic elastic coefficients estimated in the hypertensive heart model that is prone to triggering HFpEF demonstrated significant increase in one compressional direction and all three shear directions. In conclusion, this dissertation uses cMRE to demonstrate the potential of spatiotemporal isotropic and anisotropic myocardial stiffness as a diagnostic metric in heart failure porcine models.

Committee:

Bradley Clymer (Advisor); Arunark Kolipaka (Advisor); Patrick Roblin (Committee Member); Richard White (Committee Member)

Subjects:

Biomechanics; Biomedical Engineering; Biomedical Research; Computer Engineering; Electrical Engineering; Medical Imaging; Radiology

Hackworth, Ruth M.Radiation Science Educators' Perception of Obstacles in the Use of Critical Thinking
Master of Science, The Ohio State University, 2010, Allied Medicine

The purpose of this study was to discover educators’ perceptions of their current level of competence in teaching and assessing critical thinking. It defined the difficulties educators are faced with and their perceived confidence in their level of skill. Radiation science educators from both radiography and radiation therapy programs were surveyed on-line through Survey Monkey®. A four part survey was completed by 317 educators for a 46% response rate. Sections of the survey included demographics, perceptions on teaching critical thinking skills to students, frequency of obstacles impeding the use of critical thinking, and open ended questions providing further comments on obstacles, methods, skill development and assessment of critical thinking.

Radiation science educators are confident in their use of critical thinking skills and perceive critical thinking to be an essential element in the education of the student. Educators were satisfied with their self-reported level of skill in critical thinking, but identified several areas needing improvement such as the ability to demonstrate, implement and assess critical thinking skills as well as the need to develop and implement new strategies. The confidence and skill level showed a significant difference when comparing the education level of the program director, particularly between those with a master’s degree and a doctoral degree. Several factors were identified in the study as being obstacles impeding the educators’ development of critical thinking in the classroom. The findings provide a basis for the educators to begin to improve their skills and methods for teaching critical thinking.

Committee:

Jane Case-Smith, EdD, OTR/L, FAOTA (Advisor); Jill Clutter, PhD (Committee Member); Nina Kowalczyk, PhD, RT(R)(QM)(CT), FASRT (Committee Member)

Subjects:

Education; Educational Evaluation; Health Education; Higher Education; Radiation; Radiology; Teacher Education; Teaching

Keywords:

critical thinking; obstacles;

El-Dakdouki, Mohammad H.Synthesis of Agents Targeting Cancer Cells While Reducing MDR Liability
Doctor of Philosophy in Medicinal Chemistry, University of Toledo, 2009, Medicinal Chemistry

The use of paclitaxel (PAC) for the treatment of certain types of cancers has been limited by its poor water solubility, toxicity to rapidly dividing normal cells, and weak activity against drug resistant tumors. Thus, there is a need to develop PAC conjugates that are selective toward cancer cells, while also having enhanced aqueous solubility and a reduced liability toward multidrug resistance (MDR). Previous studies in the Center for Drug Design and Development (CD3) have demonstrated that conjugating an acidic moiety on the Northern edge of PAC decreases the P-glycoprotein (Pgp) mediated MDR interactions. The acidic moiety not only reduces MDR liability, but also increases the aqueous solubility of these PAC conjugates. To further explore this structure-activity relationship (SAR) theme, several PAC analogues have been designed to examine the effect on MDR liability of different functional groups, such as amino acids, aliphatic acids, and alcohols.

Selective targeting of cancer cells can be achieved by attaching a tumor recognizing agent or ‘address’ molecule to the anticancer drug wherein the address can then selectively bind to receptors over-expressed on cancer cells. γ-Linked glutamic acid residues (dipeptides and tripeptides), recognized by PSMA enzyme over-expressed on prostate cancer cells, were conjugated to PAC’s Northern edge to selectively target prostate cancer and its malignancy sites. In addition, a novel peptidomimetic analogue, CD3-246, was synthesized to target prostate cancer at the late stages of the disease. The latter inhibits the secondary processing enzyme Peptidylglycine α-Amidating Monooxygenase (PAM) that is believed to be crucial in activating growth hormones essential for hormone-independent tumor growth. Alternatively, several PAC-RGD conjugates have been designed to selectively target breast cancer cells. The RGD peptide is recognized by many of the integrin receptors, especially αvβ3 which is over-expressed on blood vessels undergoing angiogenesis. In addition, the RGD address was utilized to develop a second generation contrast agent that may improve the accuracy of ultrasound imaging for breast cancer diagnosis. This was done by attaching a perfluorinated hydrocarbon chain as the ‘cargo’ for the RGD address system.

In another closely-related aspect of this overall ‘targeting’ program, several anthrapyrazole analogues were also designed in an attempt to overcome the side-effect toxicity of the anthracyclins when used to treat cancer. The proposed analogues were designed to have increased antitumor activity and reduced cardiotoxicity (being less prone to bioreduction).

Committee:

Paul W. Erhardt, PhD (Advisor); L.M.V. Tillekeratne, PhD (Committee Member); Jeffrey G. Sarver, PhD (Committee Member); Steven M. Peseckis, PhD (Committee Member); Miles P. Hacker, PhD (Committee Member)

Subjects:

Chemistry; Organic Chemistry; Pharmaceuticals; Radiology

Keywords:

Paclitaxel; Prostate cancer; Breast cancer; Hypoxia; MDR

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