Search Results (1 - 25 of 116 Results)

Sort By  
Sort Dir
 
Results per page  

Chen, ZhiangDeep-learning Approaches to Object Recognition from 3D Data
Master of Sciences, Case Western Reserve University, 2017, EMC - Mechanical Engineering
This thesis focuses on deep-learning approaches to recognition and pose estimation of graspable objects using depth information. Recognition and orientation detection from depth-only data is encoded by a carefully designed 2D descriptor from 3D point clouds. Deep-learning approaches are explored from two main directions: supervised learning and semi-supervised learning. The disadvantages of supervised learning approaches drive the exploration of unsupervised pretraining. By learning good representations embedded in early layers, subsequent layers can be trained faster and with better performance. An understanding of learning processes from a probabilistic perspective is concluded, and it paves the way for developing networks based on Bayesian models, including Variational Auto-Encoders. Exploitation of knowledge transfer--re-using parameters learned from alternative training data--is shown to be effective in the present application.

Committee:

Wyatt Newman, PhD (Advisor); M. Cenk Çavusoglu, PhD (Committee Member); Roger Quinn, PhD (Committee Member)

Subjects:

Computer Science; Medical Imaging; Nanoscience; Robotics

Keywords:

deep learning; 3D object recognition; semi-supervised learning; knowledge transfer

Zaidi, Syed Anwar HyderOptical Redox Imaging of Metabolic Activity
Master of Science in Biomedical Engineering (MSBME), Wright State University, 2016, Biomedical Engineering
Fluorescence imaging can be used to determine tissue metabolism, which is an indication of the cellular functionality. Metabolic contrast is useful for the early detection of several medical conditions such as cancer, diabetes, lung diseases etc. This study aims to use fluorescence imaging to quantify NADH and FAD, which are cellular metabolic indicators. A parameter known as Redox ratio, can be used to study metabolic state of several tissue types and disease states. To quantify the Redox ratio, three fluorescence imaging systems were optimized to measure the fluorescence signal from NADH and FAD. The first system was a camera based model suitable for laboratory and clinical settings. The second and third were compact versions of the same instrument. The systems were characterized and brain cancer cells were measured using the camera-based system and the compact model, which resulted in a similar Redox ratio.

Committee:

Ulas Sunar, Ph.D. (Advisor); Jaime Ramirez-Vick, Ph.D. (Committee Member); Debra Mayes, Ph.D. (Committee Member)

Subjects:

Biomedical Engineering; Biomedical Research; Biophysics; Electrical Engineering; Medical Imaging; Optics

Keywords:

Fluorescence imaging; cancer diagnosis; compact devices; wireless devices; optical imaging

Poon, Chien SingEarly Assessment of Burn Severity in Human Tissue with Multi-Wavelength Spatial Frequency Domain Imaging
Master of Science in Biomedical Engineering (MSBME), Wright State University, 2016, Biomedical Engineering
Burn injuries such as thermal burns, which are caused by contact with flames, hot liquids, hot surfaces, and other sources of high heat as well as chemical burns and electrical burns, affects at least 500,000 people in the United States, to which 45,000 of them require medical treatment and 3,500 of them result in death. It has also been reported that in the United States alone, fire results in a death approximately every three hours and an injury every 33 minutes. Early knowledge about burn severity can lead to improved outcome for patients. In this study, the changes in optical properties in human skin following thermal burn injuries were investigated. Human skin removed during body contouring procedures was burned for either 10 or 60 seconds using a metal block placed in boiling water. Multi-wavelength spatial frequency domain imaging (SFDI) measurements were performed on each sample and the optical properties (absorption and scattering parameters) were obtained at each wavelength. Multi-wavelength fitting was used to quantify scattering parameters, and these parameters were compared to histologic assessments of burn severity. Our results indicate substantial changes in optical parameters and changes, which correlate well with respect to burn severity. This study shows the characterization of thermal burn injury on human skin ex vivo by using the optical method of SFDI with high sensitivity and specificity. Due to more challenging conditions of layered skin structures with differing thickness in humans, ongoing work tackles combining high-resolution ultrasound imaging with SFDI for more accurate quantification of optical properties during in vivo clinical studies.

Committee:

Ulas Sunar, Ph.D. (Committee Chair); Ping He, Ph.D. (Committee Member); Jeffrey Travers, M.D. Ph.D. (Committee Member)

Subjects:

Biomedical Engineering; Biomedical Research; Biophysics; Cellular Biology; Engineering; Medical Imaging; Optics; Physics

Keywords:

Optical Imaging; Medical Imaging; burn wound assessment; diagnosis; fluorescence; multispectral imaging; optical properties; quantitative assessment; skin burn; spatial frequency domain imaging; system; tissue scattering; wounds

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;

Gill, Sukhdeep KaurA Study of Evaluation of Optimal PTV Margins for Patients Receiving Prostate IGRT based on CBCT Data Dose Calculation
Master of Science (MS), University of Toledo, 2014, College of Medicine
Image-Guided Radiation Therapy (IGRT) is used in the treatment of prostate cancer to assist in precise dose delivery to the tumor and to maximize sparing of normal structures. The prostate, bladder, rectum and femoral heads can be imaged before every treatment and, with the use of Cone beam Computed Tomography (CBCT) imaging, the actual dose delivered to these organs can be monitored based on the patient’s daily anatomy. Daily set-up variations during prostate IMRT yields differences in the actual doses vs. expected doses received by the prostate, rectum and bladder. This study evaluates the optimal PTV margins for patients receiving CBCT-guided prostate IMRT based on the daily CBCT dose calculation. To determine the optimal PTV margin for CBCT-guided prostate IMRT, the prostate and organ at risk doses were estimated from daily CBCT and compared to those expected from planning. Four plans were generated with different CTV to PTV margins and these plans were transferred onto the daily CBCT. The actual delivered doses to the prostate, contoured as the CTV, were calculated on daily CBCTs using anatomy specific CT to density curves. Evaluation of the dose-volume histograms showed that a 3-5mm PTV margin was optimal for prostate IMRT, when daily CBCT is used for image guidance. The second part of this study includes a volumetric dose comparison of the rectum and bladder based on daily CBCT with respect to planned doses. The volume of the bladder and rectum changes during treatment and has an effect on the cumulative dose received by these organs. It was observed that the volumetric dose received by the bladder decreases as the volume of the bladder increases. There was no particular trend observed between volumetric dose and rectal volume.

Committee:

David Pearson, Dr (Advisor); Ishmael Parsai, Dr (Committee Member); Krishna Reddy, Dr (Committee Member)

Subjects:

Medical Imaging; Oncology; Physics

Kalra, PrateekLeft Ventricle Volume Reconstruction to Minimize Scanning Time: Slice-Fitting Method
Master of Science in Biomedical Engineering (MSBME), Wright State University, 2015, Biomedical Engineering
Assessment of left ventricle volume is usually done for diagnosis and prognosis of heart diseases. Slice-summation method is a standard method used to compute left ventricle volume where region of interest from several short axis (SA) slices are added. There are some limitations to this method, however. It requires short-axis slices to be taken parallel to the mitral valve plane from the base to apex. Moreover, scanning several short-axis slices is a tedious and time consuming process especially for studies that require several hundreds datasets. There are some existing methods to reconstruct left ventricle volume but most of them depend on several SA slices for accuracy. The ones that claim to use fewer slices have complex algorithm that can not be easily implemented and customized to individual's application. This thesis proposes a slice-fitting method that can be implemented using MATLAB's Image Processing Toolbox. The slice-fitting method uses one short-axis slice from the middle region of left ventricle and two orthogonal long axes (sagittal and coronal) slice to estimate volume. The correlation between the volume computed by slice-summation and slice-fitting method is found to be greater than 0.5 and it was when volume estimated by slice-fitting method used only one LA and one SA slice. This report also provides some optimization techniques that can be used to improve the imaging protocol that in turn can make the use of slice-fitting method more efficient.

Committee:

Nasser Kashou, Ph.D. (Advisor); Kimerly Powell, Ph.D. (Committee Member); Caroline Cao, Ph.D. (Committee Member); Arthur Goshtasby, Ph.D. (Committee Member)

Subjects:

Biomedical Engineering; Medical Imaging

Keywords:

left ventricle, volume, reconstruction, mouse heart, minimize; scanning; time

Thomas, Elinor LynnA Retrospective Study of MDCT Chest Examinations with Two Different Doses of IV Contrast Media
Master of Science, The Ohio State University, 2015, Allied Medical Professions
Purpose: Chronic kidney disease (CKD), has been recognized as a global public health problem, and may affect up to 35% of the adult population worldwide. One method of lessening the occurrence of CKD is to decrease the incidence of Contrast Induced Acute Kidney Injury (CIAKI) which occurs when acute renal dysfunction is diagnosed after the intravascular injection of water soluble iodinated contrast media during radiologic examinations. Since CIAKI occurs in up to 15 percent of the general population receiving intravascular iodine-based contrast agents, recommendations include the use of the lowest possible dose of iso-osmolal or selected low-osmolal contrast. Based on these recommendations and guidelines, it is important to identify methods to decrease the dose of intravascular contrast for radiologic exams in order to lessen the possibility of adverse kidney events. The purpose of this study is to compare the quality and diagnostic capabilities for which two contrast-enhanced routine MDCT chest scans were performed, using two different doses of iodinated water soluble IV contrast media. Methods: This was a retrospective study of an existing image database to compare image quality of two routine contrast-enhanced MDCT chest scans, each performed on the same patient using two different doses of water soluble IV contrast media, one with 100mL of high concentration iodinated IV contrast media, and one with 75mL of high concentration iodinated IV contrast media. The diagnostic image quality was evaluated based upon image contrast resolution as measured by regions of interest (ROI’s) in Hounsfield Units (HU’s) of the ascending aorta, the pulmonary root and the descending aorta; and an acceptable diagnostic image quality as subjectively interpreted by two radiologists, using a standardized 3-point image quality scale Results: When calculating for a statistical difference in contrast between the 75mL and 100mL contrast exams, the independent samples t-test results demonstrated that there is a statistically significant difference in the HU’s between the 100mL contrast dose and the 75mL contrast dose (p < .05). However, the results also demonstrated that the subjective radiologist readings of the CT chest scans utilizing 75mL doses, answered the clinical questions and were diagnostically satisfactory. Conclusions: Therefore, this study suggests that CT chest protocols may be adjusted from 100mL to 75mL, by lowering the overall amount of high concentration iodinated contrast media by 25mL, utilizing similar updated CT scanners and patient weights of 210 kilograms or less without degrading the image quality or the ability of the radiologist to make a diagnostic interpretation. Future prospective studies should include iodinated IV contrast dosing based on individual patient needs and characteristics.

Committee:

Georgianna Sergakis, PhD (Advisor); Nina Kowalczyk, PhD (Committee Member); Kay Wolf, PhD (Committee Member)

Subjects:

Medical Imaging; Medicine

Keywords:

CT Chest; MDCT Chest; Enhanced CT Chest; Iodine Contrast Media; CIN; Contrast Induced Nephropathy;CIAKI

Rollakanti, Kishore ReddyProtoporphyrin IX Fluorescence for Enhanced Photodynamic Diagnosis and Photodynamic Therapy in Murine Models of Skin and Breast Cancer
Doctor of Engineering, Cleveland State University, 2015, Washkewicz College of Engineering
Protoporphyrin IX (PpIX) is a photosensitizing agent derived from aminolevulinic acid. PpIX accumulates specifically within target cancer cells, where it fluoresces and produces cytotoxic reactive oxygen species. Our aims were to employ PpIX fluorescence to detect squamous cell carcinoma (SCC) of the skin (Photodynamic diagnosis, PDD), and to improve treatment efficacy (Photodynamic therapy, PDT) for basal cell carcinoma (BCC) and cutaneous breast cancer. Hyperspectral imaging and a spectrometer based dosimeter system were used to detect very early SCC in UVB-irradiated murine skin, using PpIX fluorescence. Regarding PDT, we showed that low non-toxic doses of vitamin D, given before ALA application, increase tumor specific PpIX accumulation and sensitize BCC and breast cancer cells to ALA-PDT. These optical imaging methods and the combination therapy regimen (vitamin D and ALA-PDT) are promising tools for effective management of skin and breast cancer.

Committee:

Edward Maytin, PhD (Committee Chair); Sridhar Ungarala, PhD (Committee Member); John Turner, PhD (Committee Member); Judith Drazba, PhD (Committee Member); Anand Ramamurthi, PhD (Committee Member)

Subjects:

Biomedical Engineering; Biomedical Research; Engineering; Medical Imaging; Optics

Keywords:

Aminolevulinic acid; Protoporphyrin IX; Photodynamic therapy; Photodynamic Diagnosis; IVIS, basal cell carcinoma; squamous cell carcinoma; breast cancer; vitamin D; differentiation

Deshpande, AditiMufti-Dimensional Polarimetric Pattern Recognition & Classification Techniques for Immunohistochemical Imaging of Cancer
Master of Science in Engineering, University of Akron, 2014, Biomedical Engineering
The most important step in treating cancer is an accurate early diagnosis and proper surgical removal. In the first part of this study, statistical data mining techniques were applied to discriminate the polarimetric backscattered signals of different kinds of cancer (Squamous carcinoma and Adenocarcinoma) from each other and from normal healthy cells which included pattern recognition techniques such as KNN classification, K means clustering and fractal analysis. This classification was performed on the standard polarimetric properties of these tissues such as Depolarization, Diattenuation, Retardance, etc. The other section of this study involves an image processing system which aims at enhancing the imaging of tumor margins for efficient surgical removal of tumors based on a proper demarcation of their boundaries. This is achieved by performing thresholding-based image segmentation and statistical texture feature extraction. Clustering based techniques such as Otsu thresholding, Entropy segmentation and Mean Shift Segmentation were applied to improve the tumor demarcation and then statistical texture analysis was performed for feature extraction, followed by edge detection and contour mapping to analyze the tumor margins and their delineation.

Committee:

George Giakos, Dr. (Advisor); Dale Mugler, Dr. (Committee Member); Narender Reddy, Dr. (Committee Member)

Subjects:

Biomedical Engineering; Medical Imaging

Keywords:

imaging, image processing, imaging of tumor margins, cancer classification, pattern recognition

Kerwin, ThomasEnhancements in Volumetric Surgical Simulation
Doctor of Philosophy, The Ohio State University, 2011, Computer Science and Engineering

Computer surgical simulation has a great deal of potential in medical education and testing. However, there are numerous problems in integrating simulation software technology into a medical curriculum. Review and analysis of the data from the simulation is important to evaluate and assist students. A combination of realistic rendering for good translation of skills to the operating room and illustrative rendering to aid novices can help the simulation system target a wide range of students.

In the context of an ongoing project to develop and improve a temporal bone surgical simulator, this document describes algorithms that address these issues and provides solutions to them. In collaboration with expert surgeons, we have met some of the technological challenges that limit surgical simulation.

Storage and playback of the interactions that users have with the simulation system is achieved via a snapshot technique using forward differences for efficient compression. A technique for realistic rendering of fluid and wet surfaces in a virtual surgical environment using modern graphics hardware is explained. Using a modified distance field technique, we show how to display context around important anatomical structures in segmented datasets. A method of automatic scoring of the users of the simulator is detailed. This method involves partitioning the volume based on proximity to critical structures and then using the Earth Mover's Distance to compare the content of those partitions. Distance fields are also employed for shape analysis techniques to extract features that are used in a visualization system. This system allows expert surgeons to examine and compare the virtual mastoidectomies perfomed by residents during training.

Committee:

Han-Wei Shen, PhD (Committee Chair); Roger Crawfis, PhD (Committee Member); Raghu Machiraju, PhD (Committee Member)

Subjects:

Computer Science; Medical Imaging

Keywords:

Surgical simulation; visualization; automated assessment; volume rendering

Schmitt, Benjamin A.Utility of a Volume-Regulated Drive System for Direct Mechanical Ventricular Actuation
Master of Science in Engineering (MSEgr), Wright State University, 2013, Biomedical Engineering
Direct Mechanical Ventricular Actuation (DMVA) is a non-blood contacting cardiac assist device that augments ventricular function. The purpose of this study was to determine if a volume-regulated &#x201c;hand pump&#x201d; drive system and a pressure-regulated &#x201c;switch tank&#x201d; drive system provide equivalent levels of cardiac support. Canine (n=2) and swine (n=4) were instrumented for hemodynamic monitoring and intravascular echocardiography. DMVA support was assessed during both severe heart failure and fibrillation. Pump function was evaluated using hemodynamic measures to calculate stroke work. Myocardial function was assessed using echocardiographic speckle tracking to quantify strain rate. Results were compared between groups using paired t-tests. There were no significant differences in either pump function or myocardial strain rates between the hand pump versus switch tank during support of either the failing or fibrillating heart. These results suggest functional equivalency between the two drive system mechanisms that supports development of an automated volume-regulated system, with its corresponding benefits in reduced size, portability, and potential user-friendly control.

Committee:

David Reynolds, Ph.D. (Committee Co-Chair); Mark Anstadt, M.D. (Committee Co-Chair); Chandler Phillips, M.D. (Committee Member)

Subjects:

Biomedical Engineering; Medical Imaging

Keywords:

Direct Mechanical Ventricular Actuation; Mechanical Circulatory Support; Echocardiography; Speckle Tracking; Strain Rate; Myocardial Stretch

Jin, XianceEvaluation of Large Area Polycrystalline CdTe Detector for Diagnostic X-ray Imaging
Doctor of Philosophy, University of Toledo, 2011, Physics

Introduction of digital radiography systems and successive use of flat panel detectors revolutionized the field of diagnostic imaging. Wide dynamic range, high image quality, real-time image acquisition and processing, precise image recording, and ease of remote access are among the most prominent improvements. One of the decisive factors contributing to further advancements remains the continuous development of different X-ray detecting materials, from traditional phosphor screens in combination with secondary photodetectors for indirect detection to use of thin-film photoconductors in direct detection systems. The latter approach offers a two-fold benefit: simpler device structure resulting in lower manufacturing cost, and a high potential of providing images of superior contrast and sharpness due to inherently low signal spreading within the detector.

In the direct detection approach X-rays are absorbed by a photoconductor layer and converted to electron-hole pairs, which are then collected as electric charges on storage capacitors. Up to now amorphous selenium (a-Se) is the only photoconductor developed into direct detection type commercial medical imagers, for both general radiography and mammography applications. Detectors based on a-Se offer superior spatial resolution due to the simple conversion process. However, low atomic number and density (Z=34, ρ= 4.27 g/cm3), leading to low X-ray absorption, and high effective ionization energy (~50 eV) result in inadequate sensitivity, especially important for low exposure levels of fluoroscopic mode.

Materials of high atomic number and density have been investigated to replace a-Se. The purpose of this work is to evaluate polycrystalline Cadmium Telluride (CdTe) semiconductor material for application in large area diagnostic X-ray digital imaging in the direct detection configuration. Its high atomic number and density (Z=50, ρ= 5.86 g/cm3), low effective ionization energy (~5eV), as well as wide band gap, makes CdTe very attractive for room temperature radiation detection applications. Recent developments in large area photovoltaic applications of CdTe have moved this photoconductor to the frontiers of thin-film manufacturing and large area medical imaging.

The intrinsic image quality characteristics of the polycrystalline CdTe detector under diagnostic X-ray imaging have been investigated by Monte Carlo simulation using MCNP5 software package. The modulation transfer function (MTF), noise power spectrum (NPS), and detective quantum efficiency (DQE) of detectors of various thickness for diagnostic X-ray beams from 70 kVp to 120 kVp were determined. Thin film CdTe detector device operation was modeled with 1-D SCAPS (solar cell capacitance simulator) software package based on the energy deposition profiles obtained for diagnostic X-ray beams with Monte Carlo simulation. The sensitivity, linearity, and time response of prototype thin film CdTe detectors were measured. Electronic characteristics of a subset of thin detectors were verified against SCAPS simulation results allowing for model adjustments.

In this work we 1) calculate the diagnostic X-ray spectra of our Varian Ximatron simulator based on the measured output by tungsten anode spectral model using interpolation polynomials (TASMIP) technique, 2) study image quality characteristics, such as MTF, NPS, and DQE with MCNP5 Monte Carlo simulations, 3) investigate the device operation with SCAPS simulations, and 4) measure the device performance with a set of prototype devices. Based on our simulation and measurement results, we believe thin film polycrystalline CdTe is a promising material for direct detection large area digital medical imaging.

Committee:

E.Ishmael Parsai, PhD (Committee Chair); Dianna Shvydka, PhD (Committee Member); Michael Dennis, PhD (Committee Member); Scott Lee, PhD (Committee Member); Thomas Kvale, PhD (Committee Member)

Subjects:

Medical Imaging

Keywords:

polycrystalline CdTe; diagnostic x-ray imaging; DQE; Monte Carlo simulation; TASMIP

Lossing, Laura Ashley EiseleChanges in Ciliary Muscle Thickness with Accommodation
Master of Science, The Ohio State University, 2011, Vision Science

Purpose: To develop a measurement protocol using the Zeiss Visante™ AS-OCT to asses changes in the shape and size of the ciliary muscle with accommodation and to determine the test-retest repeatability of these measurements.

Methods: Twenty-five adults (17 females) ages 22-27 years (mean ± SD = 23.8 ± 1.1 years) were recruited. The ciliary muscle was imaged at two separate visits two weeks apart with the Zeiss Visante Anterior Segment OCT. While subjects viewed targets at two different stimulus levels (1 D and 4 D), the ciliary muscle was imaged six times and accommodation was monitored with the PowerRefractor. Ciliary muscle thickness (CMT) measurements were obtained at four muscle locations; 1 mm (CMT1), 2 mm (CMT2), and 3mm (CMT3) posterior to the scleral spur as well as (CMTMAX) at the point of maximal muscle thickness. The action of the ciliary muscle during accommodation was described by our data in two ways. The „raw change‟ was calculated as the change in ciliary muscle thickness calculated based on the accommodative target (the change in accommodation from distance to the 4D target). The „standardized change‟ was calculated as the ratio as (change in CMT/accommodative response) represented the amount of thickening or thinning that occurred in the ciliary muscle per diopter of accommodation. Finally, the repeatability measurements between visit 1 and visit 2 were analyzed using a Bland-Altman analysis.

Results: The mean accommodative response measured with the PowerRefractor at visit 1 was 3.97±0.87D with a range of -1.87 to -4.95D and -3.92±0.82 with a range of -2.79 to -5.39D at visit 2. The change in ciliary muscle thickness per diopter of accommodation was calculated based on both the accommodative stimulus and the measured accommodative response (PowerRefractor) at the four thickness locations. Ciliary muscle thinning from 1D to 4D of accommodation was statistically significant at CMT3. Thickening of the ciliary muscle with accommodation was observed at both CMT1 and CMTMAX while no statistical thickening or thinning was present at CMT2. Bland-Altman repeatability analysis between the two visits was non-significant for every muscle location. The 2D stimulus was not considered in these calculations because the majority of subjects failed to produce any accommodative effort to the 2D target.

Conclusion: The combination of the Visante Anterior Segment OCT and the PowerRefractor is a feasible tool for measuring the change in ciliary muscle thickness with accommodation. There was a wide range of accommodative responses during the time of image capture in this study. This indicates is it essential to know the accommodative response at the exact time of image capture for the most accurate calculations of change in ciliary muscle thickness with accommodation.

Committee:

Melissa Bailey, OD (Advisor); Nick Fogt, OD (Committee Member); Marjean Kulp, OD (Committee Member)

Subjects:

Medical Imaging; Ophthalmology; Optics

Keywords:

Accommodation; Myopia; Presbyopia; Ocular; Visante; Ciliary muscle

Karnik, KetakiAccuracy of Computed Tomography in Determining Lesion Size in Canine Osteosarcoma of the Appendicular Skeleton
Master of Science, The Ohio State University, 2011, Comparative and Veterinary Medicine
Multidetector contrast enhanced computed tomography with acquisition of 0.625 mm thick axial transverse images was used to measure the extent of appendicular osteosarcoma (OSA) in 10 dogs. The measured length of tumor based on CT was compared to the true length of tumor using histopathology. There was good correlation of the true length of OSA compared to the length of intramedullary/endosteal abnormalities on CT with a mean overestimation of 1.8% (SD = 15%). There was poor correlation of the true length of OSA compared to the length of periosteal proliferation on CT with a mean overestimation of 9.7% (SD = 30.3%). There was poor correlation of the true length of OSA compared to the length of abnormal contrast enhancement by 9.6% (SD = 34.8%). The measured extent of intramedullary/endosteal abnormalities using sub-millimeter thick axial transverse acquisition of images with multidetector CT should be of value in assessing patient candidacy and surgical margins for limb spare surgery. It may also be useful for evaluating response to therapy in dogs that receive chemotherapy or radiation therapy when surgery is not performed.

Committee:

E Green, DVM (Advisor); Steven Weisbrode, DVM (Committee Member); Cheryl London, DVM (Committee Member)

Subjects:

Animal Diseases; Animal Sciences; Animals; Medical Imaging; Medicine; Veterinary Services

Keywords:

CT; computed tomography; OSA; osteosarcoma; multidetector; appendicular; canine; dog; neoplasia; bone

Tkachenko, EvgeniyMeasures of Individual Resorption Cavities in Three-Dimensional Images in Cancellous Bone
Master of Sciences (Engineering), Case Western Reserve University, 2011, EMC - Mechanical Engineering
Resorption cavities result from the activity of osteoclasts, cells that remove old or damaged tissue during bone remodeling. These cavities are believed to act as stress risers, potentially impairing bone strength and increasing fracture risk. Estrogen depletion has been associated with an increase in bone remodeling, but it is unclear whether the change is due to an increase in the number of cavities, surface area of individual cavities, or both. The distribution of stress concentration due to cavities may be related to their number and size, independent of the amount of bone remodeling. Here we present and validate the first, 3D approach to measuring individual resorption cavities in cancellous bone. Additionally, cavity number and surface area are compared in a standard animal model of post-menopausal osteoporosis, the ovarietomized rat.

Committee:

Christopher Hernandez, PhD (Committee Chair); Clare Rimnac, PhD (Committee Member); Joseph Mansour, PhD (Committee Member)

Subjects:

Biochemistry; Biology; Biomechanics; Biomedical Engineering; Biomedical Research; Cellular Biology; Health Care; Mechanical Engineering; Mechanics; Medical Imaging; Molecular Biology

Keywords:

Resorption cavities; osteoporosis; biomedical imaging; bone strength; bone remodeling; 3D bone histomorphometry

Shah, ChintanEffects of Exercise Therapy on Functional Connectivity in Parkinson's Disease
Master of Sciences (Engineering), Case Western Reserve University, 2013, Biomedical Engineering
Forced-rate lower-extremity exercise has recently emerged as a potential safe and low-cost therapy for Parkinson's Disease (PD). The efficacy is believed to be dependent on high rates of exercise. In this study, we use functional connectivity (FC) MRI to further elucidate the mechanism underlying this rate-dependent effect. PD subjects were randomized to complete 8 weeks of forced, voluntary, or no exercise. Changes in brain connectivity were then analyzed as a function of pedaling rate. Changes in task-related FC (trFC) from the most affected motor cortex (*M1) to the ipsilateral thalamus were significantly positively correlated to pedaling rate. Changes in trFC between *M1 and the supplementary motor area were significantly negatively correlated to pedaling rate. This relationship persisted after 4 weeks of follow up. This indicates that patients who pedal faster tend to show stronger increases in cortico-subcortical trFC, and stronger decreases in cortico-cortical trFC.

Committee:

Jay Alberts, Ph.D. (Advisor); Kenneth Gustafson, Ph.D. (Committee Chair); Micheal Phillips, M.D. (Committee Member); Hubert Fernandez, M.D. (Committee Member); Mark Lowe, Ph.D. (Other); Erik Beall, Ph.D. (Other)

Subjects:

Biomedical Engineering; Medical Imaging; Neurosciences

Keywords:

Parkinson's Disease; exercise; Functional Connectivity; fMRI; fcMRI

Fentner, David AA Comparative Image Quality Analysis between Multi-Slice Computed Tomography and Cone Beam Computed Tomography for Radiation Treatment Planning Purposes
Master of Science in Biomedical Sciences (MSBS), University of Toledo, 2013, College of Medicine
The ability of an imaging system to accurately identify patient anatomy and provide reliable tumor information is critical in the radiation treatment planning process. As image guided radiation therapy and adaptive radiation therapy become more prevalent in treatment procedures, the image quality of these systems could perhaps be a limiting factor in their effectiveness. This research is intended to explore the differences in image quality between two separate imaging modalities commonly used in radiation therapy. A Philips Gemini TF Big Bore PET/CT and Varian True Beam On-Board kV cone beam CT imager were both assessed using the Catphan 504 image quality phantom. Ten different tests were evaluated with the phantom using several routine imaging protocols from both systems. Overall, the image quality between the cone beam and CT system was fairly consistent with one another with the exception of the low contrast detectability measurements. The effects of scatter radiation and image noise significantly reduced the cone beams ability to detect low contrast objects which ultimately degraded its image quality compared to CT.

Committee:

Michael Dennis, PhD (Committee Chair); Ishmael Parsai, PhD (Committee Member); Dianna Shydka, PhD (Committee Member)

Subjects:

Medical Imaging

Keywords:

cone beam computed tomography; computed tomography; image quality

Madaris, Aaron T.Characterization of Peripheral Lung Lesions by Statistical Image Processing of Endobronchial Ultrasound Images
Master of Science in Biomedical Engineering (MSBME), Wright State University, 2016, Biomedical Engineering
This thesis introduces the concept of implementing greyscale analysis, also known as intensity analysis, on endobronchial ultrasound (EBUS) images for the purposes of diagnosing peripheral lung tumors. The statistical methodology of using greyscale and histogram analysis allows the characterization of lung tissue in EBUS images. Regions of interest (ROI) will be analyzed in MATLAB and a feature vector will be created. A feature vector of first-order, second-order and histogram greyscale analysis will be created and used for the classification of malignant vs benign peripheral lung tumors. The tools that were implemented were MedCalc for the initial statistical analysis of receiver operating curves (ROC), Multiple Regression and MATLAB for the machine learning and ROI collection. Feature analysis, multiple regression and machine learning methods were used to better classify the malignant and benign EBUS images. The classification is assessed with a confusion matrix, ROC curve, accuracy, sensitivity and specificity. It was found that minimum pixel value, contrast and energy are the best determining factors to discriminate between benign and malignant EBUS images.

Committee:

Ulas Sunar, Ph.D. (Advisor); Jason Parker, Ph.D. (Committee Member); Jaime Ramirez-Vick, Ph.D. (Committee Member)

Subjects:

Biomedical Engineering; Biomedical Research; Biostatistics; Computer Engineering; Engineering; Health Care; Medical Imaging

Keywords:

Endobronchial Ultrasound; Medical Imaging; Image Analysis; Statistical Analysis; Machine learning; MATLAB; Histogram; Texture; Multiple Regression; Feature analysis

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

Ducay, Rey Nann Mark AbaqueDirect Detection of Aggregates in Turbid Colloidal Suspensions
Master of Science, Miami University, 2015, Physics
This thesis presents the application of an empirical model of total internal reflection (TIR) we recently developed in conjunction with a home-built sensor to detect nanoaggregates in highly scattering opaque polystyrene colloidal suspensions. The nanoaggregates are detected directly without any sample dilution or special sample preparation. Additional results on nanoaggregate detection in gold nanoparticle suspensions are presented. Preliminary tests of our model and sensor in an absorbing dye solution are also presented.

Committee:

Samir Bali, PhD (Advisor); Lalit Bali, PhD (Advisor); Jason Berberich, PhD (Advisor); Jon Scaffidi, PhD (Advisor); James Clemens, PhD (Committee Member); Karthik Vishwanath, PhD (Committee Member)

Subjects:

Analytical Chemistry; Biochemistry; Biomedical Engineering; Biomedical Research; Biophysics; Chemical Engineering; Chemistry; Experiments; Materials Science; Medical Imaging; Molecular Physics; Molecules; Nanoscience; Nanotechnology; Optics; Organic Chemistry; Physics; Polymer Chemistry; Polymers; Scientific Imaging

Keywords:

Nanoparticles; nanoparticle aggregation; empirical model; gold nanoparticles; polystyrene nanoparticles; microspheres; turbid media; TIR; total internal reflection; biosensors; highly-scattering; nanoaggregation sensing; DLS; UV-Vis; DLVO; Zeta potential

Visser, Lance CharlesEchocardiographic Assessment of Right Ventricular Systolic Function in Conscious Healthy Dogs
Master of Science, The Ohio State University, 2014, Comparative and Veterinary Medicine
There is accumulating evidence demonstrating the important role of the echocardiographic assessment of right ventricular (RV) systolic function in people affected with a variety of cardiovascular diseases. In dogs, the echocardiographic assessment of RV function is underutilized and reference values and validation studies in normal dogs are sparse. The purpose of this thesis was to study several echocardiographic indices of RV systolic function in a relatively large sample of conscious, healthy dogs (n = 80), generate reliable reference values, and validate these indices in a clinically relevant manner. Chapter 2 shows the feasibility of measuring tricuspid annular plane systolic excursion (TAPSE), percent fractional area change (FAC), pulsed wave tissue Doppler imaging-derived peak systolic myocardial velocity of the lateral tricuspid annulus (S’), and speckle tracking echocardiography-derived global longitudinal RV free wall strain and strain rate. These variables were demonstrated to be repeatable indices of RV systolic function in conscious healthy dogs. Body weight-specific reference values were calculated for these estimates of RV systolic function. Chapter 3 demonstrates that these same 5 indices of RV function can track expected positive and negative inotropic changes in RV function compared to baseline following single oral doses of pimobendan and atenolol, respectively. The results of this thesis support the use of these echocardiographic indices for the clinical assessment of RV systolic function and calls for further study of these indices in dogs affected with cardiovascular disease.

Committee:

Brian Scansen (Advisor); John Bonagura (Committee Member); Karsten Schober (Committee Member)

Subjects:

Medical Imaging; Medicine; Veterinary Services

Keywords:

Echocardiography; canine; right ventricle

Talasu, DharneeshEfficient fMRI Analysis and Clustering on GPUs
Master of Science, The Ohio State University, 2011, Computer Science and Engineering

Graphics processing units (GPUs) traditionally have been used to accelerate only parts of the graphics pipelines. The emergence of the new age GPUs as highly parallel, multi-threaded and many core processor systems with the ability to perform general purpose computations has opened doors for new form of heterogeneous computing where the GPU and CPU can be used together in accelerating the underlying computations. General-purpose computing on graphics processing unit (GPGPU, also referred to as GP2U) techniques can be used to perform highly data parallel computations and to accelerate some critical sections of an application. Accelerating the computation of fMRI analysis on a graphics processing unit is mainly attractive when used in a clinical environment.

In this thesis, I discuss methods which try to exploit the capabilities provided by GPUs to accelerate the analysis of time varying data acquired during fMRI experiments for identifying regions of activity/inactivity. Static activation maps are obtained by inspecting voxels independently with the help of statistical methods in parallel using CUDA (Compute unified device architecture) threads. I provide an efficient strategy for mapping each individual time varying voxels to GPU kernel threads for data parallel analysis of fMRI data and present GPU version of methods used in the fMRI analysis pipeline based on voxel to thread mapping technique. Also, an efficient method for octree based hierarchical clustering of voxels on a GPU and using a combination of GPU and CPU for enhanced clustering speedup is discussed. A comparison between the data parallel methods implemented on GPU and the corresponding CPU implementations and overall speed up achieved using combined GPU and CPU implementations in octree based hierarchical clustering is discussed.

Committee:

Raghu Machiraju, PhD (Advisor); Gagan Agrawal, PhD (Committee Member)

Subjects:

Medical Imaging

Keywords:

fMRI; fMRI analysis on GPU; fMRI clustering on GPU; octree; hierarchical clustering using GPU and CPU;

Kumar, MohitImage Performance Characteristics of Bio-Inspired Image Sensor
Master of Science in Engineering, University of Akron, 2013, Electrical Engineering
Over the years, polarization of the electromagnetic waves has been the prime medium for the Imaging systems to hold vital information about the surface contours, curvature of objects and locations of different materials. Bio-Inspired Imaging technology has the prospective to improve and enhance Image analysis, Long- distance surveillance of targets, Optical techniques, Navigation, Object detection and Healthcare. The rationale of this study is to explore the image formation by different insect eyes that will benefit the digital imaging with high resolution and wide field of view and the defense and military areas. For this study, architectures of different compound eyes were studied, such as Apposition, Superposition and Neural superposition. Human eye is polarization blind and without usage of an artificial polarization instrument, it cannot employ the polarization of light. Whereas, Insect vision holds numerous advantages as their compound eyes provides wide viewing angle, good tracking abilities due to large amount of photoreceptor units and foremost important can detect the polarized light. Design parameters considered for this study were, angular spacing of receptors, degree of blurring, diameter and contrast of the photoreceptors, signal-to-noise ratio, motion artifacts and the polarimetric arrangement of the eye. The five insect species that were considered for the study are Hemicordulia tau, Anoplognathus pallidicollis, Heteronympha merope, Melanitis leda and Phalaenoides tristifica. Footprints and Gaussian optical blur filters of different insects were attained. The outcome of this study designates the importance of Bio-inspired imaging in distinct areas of defense, security and healthcare applications.

Committee:

George. C. Giakos, Dr. (Advisor); Arjuna.H.L.P Madanayake, Dr. (Committee Member); Kye-Shin Lee, Dr. (Committee Member)

Subjects:

Biology; Biomedical Engineering; Biomedical Research; Electrical Engineering; Engineering; Entomology; Medical Imaging; Oncology; Zoology

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;

Clark, ElizabethModels and Mechanisms to Evaluate Tissue Engineered Vascular Graft Stenosis
Doctor of Philosophy, The Ohio State University, 2017, Comparative and Veterinary Medicine
Congenital heart disease represents the most common form of birth defect and is present in up to 1% of all live births. Of particular interest to our group is the treatment of single ventricle disease, specifically hypoplastic left heart syndrome (HLHS) in which left-sided heart structures including the left ventricle, aorta, and mitral valve are malformed. We utilize tissue engineering principles to provide palliative treatment with Tissue-Engineered Vascular Grafts (TEVG) that allow for growth of the child’s own tissues. The TEVG overcomes limitations present in other composite grafts including thrombogenicity and lack of growth capacity. One limitation of our TEVG is that a small percentage of children develop critical stenosis requiring the utilization of interventional cardiovascular techniques. Developing both large and small animal models of TEVG stenosis will allow us to better understand clinical data sets as well as provide models to better characterize the development of neotissue formation and stenosis. The long-term goal of this project is to develop a second-generation composite vascular graft for use in children. The objective of this study is to elucidate the mechanism of TEVG neotissue formation in immunocompetent mice (Mus musculus) and characterize neotissue formation in a sheep (Ovis aries) model. Echocardiography, angiography, and magnetic resonance imaging are routinely used to evaluate children that have received the TEVG to treat HLHS. While angiography remains the clinical gold standard for evaluation of the lumen it only indirectly evaluates the vessel wall. Therefore, we sought to evaluate intravascular ultrasound (IVUS) to characterize neotissue formation in an in vivo ovine surgical model. IVUS demonstrated close correlation to angiographic and histologic changes. Additionally, IVUS measurement of graft lumen morphometry correlates with angiography measurements. This provides further data to support the use of IVUS in a clinical setting. Future preclinical experiments will utilize this modality as an additive approach to characterize the development of TEVG stenosis and neotissue remodeling over time, with specific regard to response to treatment with both interventional and therapeutic approaches. Previous research by our lab C57BL/6 mice has suggested that the transforming growth factor-ß (TGF-ß)/Smad2-3 pathway is involved in the development of TEVG stenosis. While the specific role of the TGF-ß pathway in the development of stenosis remains unknown, this pathway is upregulated in stenotic TEVG. To this end, this work seeks to evaluate the TGF-ß pathway in Cdh5-lineage cells in vivo in mice implanted with TEVG. A conditional genetic murine model was developed with endothelial-derived (Cdh5) loss of the TGF-ß receptors, TßRI and TßRII. Although TEVG have a low incidence of stenosis in both treated and control animals, Cdh5 TGF-ß pathway modulation results in altered neotissue formation including collagen production and polymeric degradation at early timepoints. We rationalize that by elucidating the cell(s) of origin for the neotissue and the role of TGF-ß receptor pathway will enable the development of targeted therapies in combination with TEVGs to improve clinical outcomes for children.

Committee:

Christopher Breuer, MD (Advisor); Keith Gooch, PhD (Committee Member); Krista La Perle, DVM, PhD (Committee Member); Joy Lincoln, PhD (Committee Member)

Subjects:

Biology; Biomedical Engineering; Biomedical Research; Medical Imaging; Medicine; Pathology

Keywords:

CHD; HLHS; TEVG; tissue engineering; IVUS; TGF-beta; stenosis

Next Page