8,670 research outputs found
Application of CT in Diagnosing Carcinoma of the Maxillary Sinuses : PART 2: An Experimental Study of Pitfalls Encountered when Diagnosing Carcinoma of the Maxillary Sinuses with CT
No full text1982-03A phantom simulating the transverse section of the maxillary sinuses was constructed for experimentation with various CT scanners to study the following: (1) the occasional inability to image the very thin posterior-lateral walls which have no real bone defects, and (2) to verify whether or not the bony walls surrounding the maxillary sinuses are actually as thick as they appear on CT. The phantom was made of an acrylic cylinder containing three cavities simulating the maxillary sinuses and the nasal cavity and filled with water. The walls, made of thin aluminum and acrylic plates and placed between water and air, disappeared in some CT images. The thickness of the walls calculated from CT values was greater than the true thickness imaged by each CT scanner. The author stresses that in CT images, either experimentally or clinically, thin bony walls placed between water and air or fat tend to disappear, and that bony walls tend to appear thicker than their true thickenss.departmental bulletin pape
Patients' & Healthcare Professionals' Values Regarding True- & False-Positive Diagnosis when Colorectal Cancer Screening by CT Colonography: Discrete Choice Experiment.
No full textTo establish the relative weighting given by patients and healthcare professionals to gains in diagnostic sensitivity versus loss of specificity when using CT colonography (CTC) for colorectal cancer screening
X-ray CT Scans of Amia calva (Bowfin) (UMMZ 235291)
No full textX-ray CT Scans of the whole body of Amia calva (UMMZ 235291; Georgia, Troup West Point Resevoir, 0.4 mi NE of Cameron Mill Rd crossing; collected by Auburn University College of Fisheries, 29 July 1975) for Dr. Julian Humphries of the University of Texas at Austin and Dr. Timothy Rowe of the Department of Geological Sciences, The University of Texas at Austin. Scanned by Matthew Colbert 12 March 2003. The specimen was scanned from the bottom to the top, but the images are not flipped.
Voxel Size X and Y=0.0351mm, Z=0.1237 mm. Total slices = 1071.
Please acknowledge The University of Texas High-Resolution X-ray CT Facility (UTCT) when using this data
A virtual collection of North American acorn worms, including new species and the utility of CT scans in their taxonomy
No full textRésumé
Les entéropneustes, avec les Pterobranchia et les Planktospaeroidea, constituent le petit phylum deutérostomien d’Hemichordata, qui est généralement considéré comme une première ramification de la lignée en direction des Chordata. On s’attend à ce que le groupe détienne des indices sur l'évolution de la notocorde des chordés, du tube neural, des arcs branchiaux et de la glande thyroïde (Sato et al., 2008 ; Cameron et al., 2000). Je présente ici une étude taxonomique détaillée de nouvelles espèces de certaines familles et des études détaillées de leurs embryons et de leur structure musculaire.
Dans le premier chapitre, j'ai fourni un contexte général sur les Enteropneusta (habitudes de vie, évolution, biogéographie et fossiles) et un diagnostic des familles d'Enteropneusta.
Dans le chapitre deux, j'ai décrit une nouvelle espèce de la famille des entéropneustes Ptychoderidae d'Amérique du Nord en utilisant des méthodes histologiques traditionnelles, Balanoglossus sonorensis nov. sp., originaire du golfe de Californie, cette espèce se distingue de toutes les autres espèces du genre par la présence d'un long sillon médidorsal très profond sur la proboscis, du tissu conjonctif massif au centre du coelome et de la formation rapide et complète de les plaques radiales de la trompe. Le mésentère ventral du collier et l'emplacement des pores gonadiques du tronc sont uniques à cette espèce. Le chapitre trois a fourni une description formelle de Balanoglossus occidentalis, de Puget Sound, Washington, basée sur un manuscrit de W. E. Ritter. Les caractéristiques uniques de cette espèce comprennent. Le péricarde ne s'est pas formé
en deux cornes et un glomérule qui s'étendaient largement sur la surface du péricarde et s'étendaient largement sur les parties latérales et ventrales de la stomocordé. Le cordon nerveux du collier a une seule cavité et la partie digestive du tronc était plus petite que la partie branchiale. Dans le chapitre quatre, j’ai quantifié l'efficacité de la micro-tomodensitométrie (CT-scan) dans
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la taxonomie des entéropneustes. J’ai trouvé que le CT-scan est une alternative potentielle à l'histologie pour des spécimens uniques ou rares, mais il constitue plutôt un complément à l'histologie qui rend la taxonomie plus accessible et compréhensible pour les non-spécialistes. Au chapitre cinq, j'ai décrit l'espèce Schizocardium karankawa sp. nov (famille des Spengelidae) de la Laguna Madre, Texas, comprenant une phylogénie moléculaire, des détails sur sa fécondation et son développement avec un accent particulier sur son développement musculaire à travers la larve de tornaria et jusqu'au stade juvénile du ver.
Au chapitre six, j'ai créé une collection virtuelle des entéropneustes d'Amérique du Nord basée sur des spécimens holotypes collectés par Cameron et empruntés au Musée national d'histoire naturelle (Smithsonian). Ces données comprennent des numérisations numériques haute résolution de chaque lame histologique comprenant les holotypes, les détails de la collection, notamment le nom du collectionneur, l'emplacement, les dates et la coloration fixatrice et histologique. La collection virtuelle est disponible sur Canadensys https://www.canadensys.net/, un membre actif du Global Biodiversity Information Facility (GBIF). Ce chapitre est important, car la numérisation de la collection d’entéropneustes apportera de nombreux avantages, notamment la création d'une documentation constante des collections, le suivi des changements dans la répartition des espèces au fil du temps et l’accès à une grande diversité de morphologies pour comprendre les variations intraspécifiques et interspécifiques.
Dans le chapitre sept, j'ai fourni une conclusion générale, la motivation de mon travail, un résumé du travail de taxonomie effectué dans le laboratoire Cameron et la stratégie de tomodensitométrie. Enfin, j'ai fourni un bref aperçu de mes perspectives d'avenir concernant mon désir d’étendre ce travail par l'étude de la taxonomie des entéropneustes nord-africains.Abstract
The Enteropneusta (acorn worms), with the Pterobranchia, and the Planktospaeroidea constitute the small deuterostome phyla Hemichordata, which is generally regarded as an early offshoot of the line to the Chordata. The group is expected to hold clues about the evolution of the chordate notochord, neural tube, gill bars, and thyroid gland (Sato et al., 2008; Cameron et al., 2000). Here, I present a detailed taxonomic study of new species of some families and some detailed studies of their embryos and muscular structure.
In the first chapter, I provided a general background of Enteropneusta (life habits, evolution, biogeography, and fossils) and a diagnosis of Enteropneusta families.
In chapter two, I described one new species of the family Ptychoderidae acorn worm from North America using traditional histological methods, Balanoglossus sonorensis nov. sp., from the Gulf of California. This species is different from all the other Balanoglossus species by the presence of a deep, long middorsal groove on the proboscis, the massive connective tissue in the center of the coelom in conjunction with the formation of the proboscis radial muscle plates. The collar ventral mesentery and the location of the trunk gonadal pores are unique to this species.
Chapter three provided a formal description of Balanoglossus occidentalis from Puget Sound, Washington, based on a manuscript by W.E. Ritter. Unique characteristics of this species include the following: The glomerulus spreads widely across the pericardium's surface and extends down over the stomochord's lateral and ventral portions. The collar nerve cord has a single cavity, and the digestive portion of the trunk is smaller than the branchial portion.
In chapter four, we quantified the efficacy of micro-computed tomography (CT scans) in acorn worm taxonomy. We found that CT scans are a potential alternative to histology for
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unique or rare specimens, but they are more of a complement to histology that makes taxonomy more accessible and understandable for non-specialists.
In chapter five, I described the species Schizocardium karankawa sp. nov (family Spengelidae) from Laguna Madre, Texas, including a molecular phylogeny, details of its fertilization and development with particular emphasis on its muscle development through the tornaria larva and into juvenile worm stage. In chapter six, I created a virtual collection of acorn worms from North America based on holotype specimens collected by Cameron and borrowed from the National Museum of Natural History (Smithsonian). These data include high-resolution digital scans of every histological slide that comprises the holotypes and the collection details, including the collector’s name, location, dates, and fixative and histological stain. The virtual collection is available on Canadensys https://www.canadensys.net/ an active member of the Global Biodiversity Information Facility (GBIF). This chapter is significant because digitizing the acorn worm collection will bring many benefits, including the creation of a constant document of collections, tracking changes in species distributions over time, and providing a wide diversity of morphologies to understand intraspecific and interspecific variation. In chapter seven, I provided a general conclusion, the motivation of this thesis research, a summary of the taxonomic work from the Cameron lab, and the CT scan strategy. Finally, I provided a brief overview of my desire to continue this work by expanding on the knowledge of North African acorn worms
Size Reducing the Conventional CT-scanner
No full textThe goal of this project is to perform a pre-study for taking a step toward implementing CT-scanners into medical transportation, and to answer the following questions. Can a miniaturized CT-scanner be created from lower end hardware without compromising image quality? Which image filters are optimal to obtain the clearest, least noisy images from the created CT-scanner? To answer these questions, a literature study is performed and the study shows that a highpass filter combined with flat field correction and a contrast enhancing filter is the most efficient way to increase the image detail in an X-ray image. The image filter is created in MATLAB and the CT-scanner software is created with Python. This project concludes that it is possible with the right hardware and software implementations, to create a miniature CT-scanner as images of both organic and inorganic objects are taken, filtered and their internal structure displayed
An approach to increasing the resolution of industrial CT images based on an aperture collimator
No full textThe spatial resolution of CT images is dominated by the focal spot size when it is large relative to the detector cells. We propose an approach to increase the spatial resolution by utilizing an aperture collimator. The aperture collimator is specially designed and placed in front of the X-ray source so that the rays penetrating the collimator form a set of narrow fan beams. Then an iterative algorithm is introduced to reconstruct CT images from the data obtained by scanning the narrow fan beams. Numerical experiments show that the proposed approach could significantly increase the resolution of the CT images. Furthermore, this approach is also robust against some challenging cases, such as the examination of low contrast object, reconstruction based on multi-energy data and perturbation of geometric errors in CT systems. (C) 2013 Optical Society of AmericaOpticsSCI(E)EI1ARTICLE2327946-279632
Author Co-Citation Analysis (ACA): a powerful tool for representing implicit knowledge of scholar knowledge workers
No full textIn the last decade, knowledge has emerged as one of the most important and valuable organizational assets. Gradually this importance caused to emergence of new discipline entitled ―knowledge management‖. However one of the major challenges of knowledge management is conversion implicit or tacit knowledge to explicit knowledge. Thus Making knowledge visible so that it can be better accessed, discussed, valued or generally managed is a long-standing objective in knowledge management. Accordingly in this paper author co- citation analysis (ACA) will be proposed as an efficient technique of knowledge visualization in academia (Scholar knowledge workers)
Verbeterde beeldreconstructie bij CT-scanners
No full textDe CT-scanner heeft een belangrijke rol in de medische wereld. Helaas gebruikt de CT-scanner voor het opstellen van een scan schadelijke straling. In dit onderzoek is nagegaan of er een betere beeldreconstructietechniek te vinden is voor het opstellen van een CT-afbeelding met gebruik van minder straling.De standaard voor het opstellen van een CT-afbeelding is het gebruik van de 2-norm. Vergelijken we de CT-afbeeldingen geconstrueerd met de 2-norm met CT-afbeeldingen geconstrueerd met de 1-norm en 0.5-norm dan zien we dat de 1-norm visueel het beste resultaat oplevert.Naast het vergelijken van de verschillende normen hebben we ook verschillende epsilon-regularisatiemethodes bekeken. De numerieke experimenten met de verschillende epsilon-regularisatiemethodes hebben we uitgevoerd op een systeem met 0%, 3% en 10% ruis, om te onderzoeken welke methode het beste toepasbaar is in de praktijk. Van de door ons geteste epsilon-regularisatiemethodes bleek de epsilon-regularisatie met epsilon := epsilon/2 met startwaarde epsilon = 10^(-8) en gebruik van de 1-norm de meest geschikte methode om een onderbepaald CT-probleem op te lossen
Molecular imaging using positron emission tomography in gastrointestinal malignancy
No full textPositron Emission Tomography (PET) with 18F-FDG has emerged as a powerful tool in oncology. Furthermore, recent advent of PET/CT and novel tracers are continually expanding its role. This thesis investigates its application in two solid cancer models.
In the diagnosing of primary pancreatic cancer, 18F-FDG PET/CT was shown to be more accurate than conventional CT. It did not add information to locoregional staging of disease but impacted management of patients with potentially operable tumours, by accurately confirming the presence / absence of metastases. In the pre-operative staging of patients with colorectal liver metastases (CLM), 18F- FDG PET/CT was also superior to CT in assessing extrahepatic disease, where it again impacted management. The accuracy of detecting hepatic disease was similar for both. Compared to PET alone, PET/CT improved the accuracy of lesions localization and interpretation.
Next, the feasibility of imaging with the novel thymidine analogue tracer 18F-FLT was investigated. Overall, 18F-FLT PET was less accurate than 18F-FDG in detecting lesions in both cancer types, thus suggesting it to be an unsuitable tracer for routine diagnosis and staging. In the cohort of pancreatic cancer patients, 18F-FLT uptake (SUVs) were found to strongly correlate with the immunohistochemical proliferation marker, Ki-67 antigen. This supported 18F-FLT‟s potential role as a surrogate marker of proliferation. The prognostic implications of these require further investigation.
Finally, an in vitro model was use to examine early changes in 18F-FLT uptake in response to treatment with cytotoxics. At 2 hours following pulse treatment with 5-fluorouracil, (and before changes in cell numbers and cell cycle phase were seen), a dose dependent increase in 18F-FLT uptake was seen. No change was observed with 18F-FDG nor following Cisplatin treatment. This adaptive response may have a role as an early predictor of response to 5-FU (and potentially other antimetabolites), which requires further investigation
MRI-based synthetic CT in the detection of knee osteoarthritis: Comparison with CT
No full textMagnetic resonance Imaging is the gold standard for assessment of soft tissues; however, X-ray-based techniques are required for evaluating bone-related pathologies. This study evaluated the performance of synthetic computed tomography (sCT), a novel MRI-based bone visualization technique, compared with CT, for the scoring of knee osteoarthritis. sCT images were generated from the 3T T1-weighted gradient-echo MR images using a trained machine learning algorithm. Two readers scored the severity of osteoarthritis in tibiofemoral and patellofemoral joints according to OACT, which enables the evaluation of osteoarthritis, from its characteristics of joint space narrowing, osteophytes, cysts and sclerosis in CT (and sCT) images. Cohen's κ was used to assess the interreader agreement for each modality, and intermodality agreement of CT- and sCT-based scores for each reader. We also compared the confidence level of readers for grading CT and sCT images using confidence scores collected during grading. Inter-reader agreement for tibiofemoral and patellofemoral joints were almost-perfect for both modalities (κ = 0.83–0.88). The intermodality agreement of osteoarthritis scores between CT and sCT was substantial to almost-perfect for tibiofemoral (κ = 0.63 and 0.84 for the two readers) and patellofemoral joints (κ = 0.78 and 0.81 for the two readers). The analysis of diagnosis confidence scores showed comparable visual quality of the two modalities, where both are showing acceptable confidence levels for scoring OA. In conclusion, in this single-center study, sCT and CT were comparable for the scoring of knee OA.</p
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