ECG-gated multidetector computed tomography (MDCT) is an imaging modality widely utilized for the evaluation of cardiac pathology by physicians. However, there has been little research of cardiac MDCT imaging in veterinary patients. Presently, ECG-gating is an upgrade for MDCT, which few veterinary institutions currently possess. The purpose of this study was to compare image quality between a 16 non ECG-gated and 64 ECG-gated MDCT for clinically important cardiac anatomy in dogs. In a crossover trial, six dogs were scanned using 16 non ECG-gated and 64 ECG-gated MDCT. A standardized anesthetic protocol, designed to induce bradycardia (mean HR 45 bpm ± 12.6) was used. Five post-contrast sequential scans through the heart were performed for each patient when utilizing the 16 non ECG-gated MDCT, in attempt to obtain a motion free series of images of the heart. For each scan, assessment of cardiac morphology was performed by evaluating a group of 21 cardiac structures, using a 3-point scale. Each of the images were scored as 0 (motion present, scan non-diagnostic), 1 (motion present, scan diagnostic), and 2 (no motion, therefore diagnostic scan of high quality). Quality scores (QS) from all scans within a dog (30 scans total) were assigned for each cardiac structure. QS from the six ECG-gated MDCT scans were of high diagnostic quality, generating diagnostic images for all of the 21 cardiac structures evaluated for each of the 6 scans. Individual non ECG-gated scans were of variable quality, primarily generating QS of 1 or 2. A complete set of diagnostic images for all 21 structures was not achieved from an individual scan. Minimum number of non ECG-gated scans to identify a single structure was calculated, and ranged from 1-2 scans for all structures. Cumulative number of sequential non ECG-gated scans needed to achieve images of all cardiac structures was calculated and determined to be 5. A 16 non ECG-gated MDCT scanner can produce cardiac images that are similar in quality, to those of 64 ECG-gated MDCT. Cardiac motion negatively impacts image quality in studies acquired without ECG-gating. However, this can be overcome by performing multiple sequential scans through the heart. / Master of Science

Sammanfattning Inledning: Den årliga incidensen för pankreascancer är 9 per 100 000 invånare. En tidig diagnos ger förbättrad 5-årsöverlevnad men botar fortfarande få patienter. De senaste åren har den dåliga prognosen förbättras tack vare utvecklingen inom bilddiagnostiken. Författaren i denna litteraturstudie har valt att jämföra multidetektor datortomografi (MDCT) och magnetisk resonans (MR) med kontrastmedel för diagnostik av pankreastumör vid misstänkt pankreascancer. Syfte: Syftet med denna litteraturstudie är att undersöka vilken radiologisk undersökningsmetod som är att föredra vid diagnostisering av pankreascancer, MDCT eller MR. Frågeställning: Är det MDCT eller MR som är bäst vid diagnostisering av pankreascancer? Metod: En litteraturstudie baserad på 12 antal artiklar som är funna i databasen PubMed. Resultat: MDCT och MR har likvärdig diagnostisk säkerhet att upptäcka pankreastumör samt påvisa kärlinväxt och förutse operabilitet. Båda metoderna har en jämförbar hög noggrannhet för karakterisering av förändringens aggressivitet. Slutsats: Såväl MDCT och MR är likvärdiga två mycket bra radiologiska metoder för att diagnostisera pankreascancer. MDCT har fortfarande en större tillgänglighet är MR men dess nackdel är man utsätter patienterna för joniserande strålning. MR är därför en metod att föredra och med stor sannolikhet kommer dess tillgänglighet att öka kraftigt i framtiden.

No / The purpose of our study was to compare the effectiveness of 3.2 mm, 5 mm and 7.5 mm slice thicknesses in the detection and characterisation of liver lesions found on CT in patients with known or suspected malignant disease. 110 patients underwent portal phase imaging using four-slice MDCT. Two blinded observers independently read hard copy images at each slice thickness. The size and location of each lesion detected was recorded by each observer on a diagram of liver segmental anatomy. Each lesion was characterised as benign, malignant or indeterminate in nature. A diagnostic confidence score was allocated for each lesion on a scale of 1-4. The pathology or behaviour of lesions was assessed using surgery with intra-operative ultrasound (IOUS) and histology, or interval imaging with MRI, CT, or sonography. 294 lesions were detected, 64 (22%) of which were malignant. Both observers detected significantly more lesions on the 3.2 mm versus 7.5 mm slice thickness (p < 0.0001). Both observers detected more malignant lesions on 3.2 mm and 5 mm slice thicknesses versus 7.5 mm. As slice thickness decreased there was a significant increase in the sensitivity of malignant lesion detection for observer 1 (p < 0.001) and borderline significance for observer 2 (p = 0.07). As slice thickness decreased the proportion of lesions characterised as indeterminate by both observers fell. With thinner slices, both detection and characterisation of liver lesions were improved. A slice thickness no greater than 5 mm should be used to maximise both detection and correct characterisation of liver lesions.

No description available.

These PhD projects represent secondary analyses of data from the ongoing Iowa Fluoride Study (IFS)/Iowa Bone Development Study (IBDS). The aim of this dissertation was to explore the associations between period-specific and cumulative fluoride intakes from birth to age 17, and from birth to age 19 years and bone measures of participants. Also, this dissertation looked into the associations between the clinical presence of dental fluorosis and bone outcomes. Participants have been participating in the IBDS that grew out of the IFS, which is a longitudinal investigation of dietary and non-dietary fluoride exposures, dental fluorosis and dental caries. IFS participants were recruited during 1992-95 from 8 hospital postpartum wards in Iowa, and detailed questionnaires were sent every 1.5-6 months. Data on intakes from water, other beverages, selected foods, dietary fluoride supplements and dentifrice were collected from the questionnaires, and, in combination with water and beverage fluoride levels, combined fluoride was estimated. For the first dissertation project, the association between fluoride intake and peripheral quantitative computed tomography (pQCT)-derived bone outcomes at age 17 were assessed. Participants underwent pQCT of the radius and tibia (XCT-2000) at age 17 years. pQCT results of trabecular bone mineral density (BMD) and bone mineral content (BMC), cortical BMD and BMC, and compression and torsion strength were related to fluoride intake through bivariate and multivariable analyses, adjusting for height, weight, years since peak height velocity, average daily time spent in moderate-to-vigorous intensity physical activity, daily calcium intake, and daily protein intake. P-values < 0.01 were considered statistically significant rather than p< 0.05 due to multiple hypothesis tests. The mean daily fluoride intake estimated by area-under-the-curve (AUC) from birth to 17 years was 0.79 mg (SD = 0.32) for males and 0.70 mg (SD = 0.25) for females. Spearman correlation coefficients between daily fluoride intake and pQCT bone measures were weak (for females r= -0.01 to 0.15 for radius bone outcomes and -0.001 to 0.23 for tibia bone outcomes; for males r= 0.03 to 0.24 for radius bone outcomes and -0.008 to 0.27 for tibia bone outcomes). In sex-specific linear regression analyses for females, partially-adjusted for height, weight, and years since peak height velocity, statistically significant negative associations were detected between all radial bone outcomes and period-specific fluoride intake from 0-8.5 years. Significant positive associations were detected for females between period-specific fluoride intakes from 14-17 years and all tibia bone outcomes, and between period-specific fluoride intakes from 14-17 years and all radius and tibia bone outcomes for males. In the fully-adjusted models, which also included physical activity, protein intake and calcium intake, statistically suggestive negative associations were detected for females during the early fluoride intake period from 0 to 8.5 years and radial cortical bone content and torsion bone strength. A statistically suggestive positive association was found between period-specific fluoride intake from 8.5 to 14 years and torsion bone strength (pSSI) (p< 0.05) for females. For males, statistically significant positive associations were detected between fluoride intake for the period from 14 to 17 years and cortical content and torsion strength (pSSI) at the 0.01 level. The second project examined the associations between period-specific and cumulative fluoride intakes from birth to age 19 years and MDCT-derived bone outcomes at age 19. Age 19 MDCT-derived trabecular and cortical bone micro-architecture scans were acquired at the University of Iowa Comprehensive Lung Imaging Center. MDCT results of the trabecular (volumetric bone mineral density (vBMD), transpose bone mineral density (tBMD), plate trabecula bone mineral density (pBMD), plate width (TS-PW), trabecular thickness (Tb.Th), trabecular spacing (Tb.Sp), trabecular network area (Tb.NA)) and cortical (cortical bone porosity (Cb.Poro), cortical thickness (Cb.Th)) bone were related to fluoride intake through bivariate and multivariable analyses, adjusting for height, weight, years since peak height velocity, average daily time spent in moderate-to-vigorous intensity physical activity, Healthy Eating Index (HEI) score, calcium intake and protein intake. P-values < 0.01 were considered statistically significant rather than p< 0.05 due to multiple hypothesis tests. The mean daily fluoride intake estimated by area-under-the-curve (AUC) from birth to 19 years was 0.81 mg (SD = 0.33) for males and 0.69 mg (SD = 0.27) for females. Spearman correlation coefficients between daily fluoride intake and MDCT bone measures were weak (for females r= -0.001 to 0.20 for trabecular bone outcomes and -0.01 to 0.02 for cortical bone outcomes; for males r= -0.003 to 0.16 for trabecular bone outcomes and -0.09 to -0.02 for cortical bone outcomes). In sex-specific partially-adjusted regression analysis adjusted for height, weight, and years since peak height velocity, no statistically significant associations were found for females or males. In the fully-adjusted models, which also included physical activity, HEI score, and protein and calcium intakes, no statistically significant associations were found for either females or males. The third project explored the associations between dental fluorosis score at age 8 and DXA-derived bone outcomes at age 5. DXA bone assessments of the whole body, proximal femur (hip), and lumbar spine were performed at The University of Iowa in the Clinical Research Center (Hologic QDR-2000 DXA unit). The dental fluorosis score was defined as the proportion of zones with definitive or severe fluorosis per person. In the unadjusted associations between bone outcomes and dental fluorosis score, no statistically significant associations were detected for females at the 0.05 level. For males, a statistically significant negative association was found between hip BMD and dental fluorosis score. Sex-specific partial correlation coefficients were estimated between DXA-derived bone outcomes and dental fluorosis score adjusted for height, weight, physical activity, calcium intake and fluoride intake. No statistically significant associations were found for females. For males, a statistically significant negative association was detected between dental fluorosis score and hip BMD. The findings of this dissertation show that life-long intakes from combined sources for adolescents and young adults living in fluoridated areas in the United States were weakly associated with bone measures at age 17 and 19. Furthermore, it was shown that bone outcomes can’t be predicted by the score of dental fluorosis. Fluoride is a mineral that plays an important role in the mineralization of bone and teeth, as well as in dental caries prevention. Numerous professional health organizations endorse the adjusted fluoridation of public water supplies for caries prevention. Results from this dissertation will also help in supporting additional efforts to promote water fluoridation and expand its use, as this dissertation’s outcomes did not demonstrate adverse outcomes related to bone.

<p>Ogg Vorbis is a fairly new and growing audio format, often used for online distribution of music and internet radio stations for streaming audio. It is considered to be better than MP3 in both quality and compression and in the same league as for example AAC. In contrast with many other formats, like MP3 and AAC, Ogg Vorbis is patent and royalty free.</p><p>The purpose of this thesis project was to investigate how the C6416 DSP processor and a Stratix II FPGA could be connected to each other and work together as co-processors and using an Ogg Vorbis decoder as implementation example.</p><p>A fixed-point decoder called Tremor (developed by Xiph.Org the creator of the Vorbis I specification), has been ported to the DSP processor and an Ogg Vorbis player has been developed. Tremor was profiled before performing the software / hardware partitioning to decide what parts of the source code of Tremor that should be implemented in the FPGA to off-load and accelerate the DSP.</p><p> </p>

Ogg Vorbis is a fairly new and growing audio format, often used for online distribution of music and internet radio stations for streaming audio. It is considered to be better than MP3 in both quality and compression and in the same league as for example AAC. In contrast with many other formats, like MP3 and AAC, Ogg Vorbis is patent and royalty free. The purpose of this thesis project was to investigate how the C6416 DSP processor and a Stratix II FPGA could be connected to each other and work together as co-processors and using an Ogg Vorbis decoder as implementation example. A fixed-point decoder called Tremor (developed by Xiph.Org the creator of the Vorbis I specification), has been ported to the DSP processor and an Ogg Vorbis player has been developed. Tremor was profiled before performing the software / hardware partitioning to decide what parts of the source code of Tremor that should be implemented in the FPGA to off-load and accelerate the DSP.

Context: Scimitar syndrome is a congenital anomaly of pulmonary venous return where right pulmonary artery drains into right side other heart, instead of the left side, causing pulmonary hypertension resulting in shortness of breath, recurrent lower respiratory tract infections, chest pain, and fatigue. Early diagnosis and surgical intervention would correct this congenital anomaly reducing morbidity and complications in otherwise healthy young patients. Case Report: We present a case of an 18-year-old female who presented with exertional shortness of breath, fatigue, and recurrent lower respiratory tract infections. She had unremarkable physical examination but chest x-ray showed an abnormal opacity next to right heart border. Computed tomography (CT) chest was performed that showed possible scimitar syndrome. Transesophageal echocardiogram (TEE) and right heart catheterization (RHC) confirmed the diagnosis. Conclusion: Scimitar syndrome is a very rare congenital anomaly of pulmonary venous return. It is usually diagnosed in early childhood but the diagnosis may be delayed until later in adulthood. The consequences are pulmonary hypertension, right-sided heart failure, and frequent pulmonary infections resulting in increased morbidity, mortality, and frequent doctor visits for otherwise healthy young patients.

Durch die räumliche Nähe und den Verlauf ist die Circumflexarteriere (Cx) im Rahmen von chirurgischen Eingriffen an der Mitralklappe (MK) besonders gefährdet. Eine Beeinträchtigung durch chirurgische Nähte im Bereich des Anulus der MK kann zu schwerwiegenden myo- kardialen Perfusionsstörungen führen. Mittels der transösophagealen Echokardiograpie (TEE) kann der Verlauf dieser Koronararterie beurteilt werden. Eine dreidimensionale TEE in Echtzeit (RT3D TEE) stellt über volumetrische Daten zusätzliche Informationen zur Analyse der Cx bereit. Eine Visualisierung der Cx ist zudem mittels dreidimensionaler Rekonstruktion auf der Basis von Multidetector Computertomographie (MDCT) umsetzbar. Im Rahmen der vorliegenden Studie wurden retrospektiv die Daten von 30 Patienten untersucht, die eine chirurgische Rekonstruk- tion der MK erhalten hatte. Dabei wurden Dimensionen und Abstände der Cx vom Mitral- klappenanulus zwischen der präoperativen MDCT Diagnostik und den intraoperativ erhobenen RT3D TEE Daten verglichen. Es zeigte sich eine gute Korrelation für horizontale und vertikale Abstände zwischen MDCT und RT3D TEE bei geringer Korrelation für den Cx Durchmesser.:Inhaltsverzeichnis 1. Bibliographische Beschreibung 2. Einführung 2.1. Mitralklappenerkrankungen 2.2. Chirurgische Therapieoptionen 2.3. Bildgebung 2.3.1. Radiologische Diagnostik 2.3.2. Echokardiographie 2.3.3. 2D TEE vs. RT3D TEE 2.4. Zielstellung der Studie 3. Publikationsmanuskript “Analysis of circumflex artery anatomy by real time 3D transesophageal echocardiography compared to cardiac computed tomography” Int J Cardiovasc Imaging 2017;33(11):1703-1711. doi:10.1007/s10554-017-1162-7 4. Zusammenfassung 5. Anlagen 5.1. Literaturverzeichnis 5.2. Abkürzungsverzeichnis 5.3. Darstellung des eigenen Beitrags 5.4. Erklärung über die eigenständige Abfassung der Arbeit 5.5. Lebenslauf 5.6. Danksagung

Vu le caractère non-invasif des procédures d’électrophysiologie interventionnelle, la visualisation de régions anatomiques d'intérêt et une orientation adéquate en cours de procédure sont nécessaires. L'objectif de cette thèse est d'étudier, d'optimiser et d'étendre l’utilisation des modalités d'imagerie radiographique. La dose de radiation effective (ED) est calculée d’une façon spécifique au patient pour l’angiographie rotationnelle 3D (3DRA) et il est démontré qu'en ajustant l’acquisition en 3DRA et en fluoroscopie, une réduction de dose importante est possible sans compromettre la qualité d’image nécessaire à la procédure. Un protocole d'acquisition et post traitement pour obtenir une imagerie dynamique basée sur le 3DRA est présenté,permettant une réduction du bruit d'image et une segmentation d'images automatique. L'extraction d'informations dynamiques, structurelles et fonctionnelles à partir d'images MDCT, relatives à la gestion de la fibrillation auriculaire (FA) est étudiée. La fonction auriculaire globale est examinée et des cartes de mouvement régional et de tissu adipeux épicardique sont produites et liés à la FA à différents stades. Une méthode automatisée est présentée pour mesurer l’orifice de l’appendice auriculaire gauche au long du cycle cardiaque et pour optimiser le déploiement de dispositifs de fermeture. Optimiser l’usage des rayons X, les protocoles d'acquisition et les méthodes de post traitement d’images, permet d’obtenir des informations supplémentaires pertinentes aux procédures d'électrophysiologie interventionnelle depuis les modalités d'imagerie radiographiques sans compromettre la qualité d’image ou le flux de travail procédural. / Due to their non-invasive character, interventional electro physiological procedures require visualisation of anatomical regions of interest and adequate guidance of procedural manoeuvres. The aim of this thesis was to study, optimise and expand the use of radiographic imaging modalities. The first part focuses on the influence of C-arm system image acquisition parameters on radiation dose incurred by the patient. We developed a patient-specific way to calculate effective dose (ED) in 3Drotational angiography (3DRA) and showed in 3DRA and fluoroscopy that by applying adequate protocol adjustments, an important dose reduction could be obtained without compromising necessary image quality. The second part focuses on the development and validation of an acquisition and post-processing protocol for dynamic imaging using 3DRA. This method enables automatic image noise reduction and image segmentation. The third part focuses on the extraction of dynamic,structural and functional information from MDCT images, relevant to management of atrial fibrillation (AF). We studied atrial function and generated maps of regional atrial motion and epicardial adipose tissue and related them to AF burden. We also developed an automated method to measure LA appendage orifice dimensions through out the cardiac cycle to optimise measurements for deployment of closure devices.Overall we demonstrate that by optimising radiation usage, acquisition protocols and image post-processing methods, additional information relevant to interventional electrophysiological procedures can be extracted from radiographic imaging modalities without compromising image quality or procedural workflow.