Thesis (Ph.D.)--George Mason University, 2008. / Vita: p. 83. Thesis director: Juan R. Cebral. Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Computational Sciences and Informatics. Title from PDF t.p. (viewed Aug. 27, 2008). Includes bibliographical references (p. 78-82). Also issued in print.

Thesis (Ph.D.)--George Mason University, 2008. / Title from PDF t.p. (viewed Oct. 14, 2008). Thesis director: Juan R. Cebral. Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Computational Sciences and Informatics. Vita: p. 98. Includes bibliographical references (p. 90-97). Also available in print.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1963. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (MSc (Radiography))--Cape Peninsula University of Technology, 2019 / Introduction: Intracranial aneurysm coil embolization is a fluoroscopically guided interventional procedure that is often preferred over surgical clipping for the treatment of intracranial aneurysms. Fluoroscopically guided procedures are associated with high levels of radiation doses which have the potential to induce skin injuries; and this necessitates adherence to radiation protection measures, especially the optimization of radiation exposure during fluoroscopically guided procedures. Optimization of radiation exposure can be achieved by applying the as low as reasonably achievable (ALARA) principle and by implementing diagnostic reference levels (DRLs). Monitoring and documentation of radiation doses at the end of each procedure is also essential to identify patients that are at risk of developing radiation-induced injuries for possible follow-up. Aim: This research study aimed to determine the average radiation dose to patients' thyroid glands and skin during intracranial aneurysm coil embolization. The objectives were to establish preliminary DRLs for intracranial aneurysm coil embolization; to ascertain whether the anatomical location of the intracranial aneurysm had an effect on the radiation dose and to compare the measured thyroid gland and skin doses to the Monte Carlo calculated doses. Methods: A prospective quantitative research study was conducted on 34 participants who had intracranial aneurysms that required coil embolization during the study period. Radiation doses to the anterior neck of participants, over the thyroid gland region, were measured using lithium fluoride thermoluminescent dosimeters (TLDs). In addition, the air-kerma area product (KAP) values were used to determine the participants' skin dose and the DRLs. Considering that it is not possible to perform direct thyroid measurements on human beings, phantom-based simulation studies were performed to evaluate the difference between the dose measured on the anterior neck and the dose measured directly on the thyroid gland. Three different aneurysm coil embolization scenarios were simulated during the phantom-based simulation studies. TLDs were placed on the anterior neck and in the thyroid hole of the phantom, which represents the anatomical location of the thyroid gland, during each simulation. The thyroid and skin doses were also calculated using a Monte Carlo program. The measured thyroid gland and skin doses were compared to the doses obtained from Monte Carlo calculations. Results: The average percentage difference between the anterior neck doses and thyroid radiation doses was found to be 61%. This value was added to the radiation dose measured on the anterior neck of participants to obtain the thyroid absorbed doses during coil embolization procedures. The thyroid absorbed doses ranged between 3.2 and 20.95 mGy with a mean of 11.25 mGy. The KAP values ranged between 33 and 125 Gy.cm2. The DRL established during this study was 68 Gy.cm2, 616 image frames and 30 minutes of fluoroscopy time. There was no agreement between measured thyroid dose and calculated thyroid doses while there was strong positive correlation between measured and calculated skin doses. The results showed no statistically significant relationship between aneurysm location and the radiation dose. Conclusion: The skin doses in this research study were below the threshold doses suggested in the literature for deterministic effects of radiation. The study results therefore suggest that patients that undergo intracranial aneurysm coil embolization at the research site are not at risk of developing radiation-induced skin injuries. The established DRLs were also lower than internationally published DRLs for intracranial aneurysm coil embolization.

Background Superparamagnetic particles of iron oxide (SPIO) are part of a novel and exciting class of ‘smart’ magnetic resonance imaging (MRI) contrast agents that are taken up by inflammatory cells. Ultrasmall SPIO (USPIO; ~30 nm diameter) can be used to assess cellular tissue inflammation and SPIO (80-150 nm) have the potential to be used to label cells ex vivo for in vivo cell tracking studies. Objectives The aims of the thesis were therefore (i) to develop and validate quantitative MRI methodology for assessing SPIO uptake within tissues, (ii) to demonstrate USPIO accumulation within the aortic wall and its implications in patients with abdominal aortic aneurysms (AAA), and (iii) to develop and apply a Good Manufacturing Practice (GMP) compliant method of SPIO cell labelling in healthy volunteers. Methods Patients with asymptomatic AAA >4.0 cm in diameter were recruited. Imaging sequences were optimised in eight patients using a 3 tesla MRI scanner. Data were analysed using the decay constant for multi echo T2* weighted (T2*W) sequences (T2*) or its inverse (R2*) and the repeatability of these measurements was established. A further twenty-nine patients underwent MRI scanning before and 24- 36 hours after administration of USPIO. T2 and multi echo T2*W sequences were performed and ultrasound-based growth rate data were collected. Operative aortic wall tissue samples were obtained from patients undergoing open surgical aneurysm repair. A GMP compliant protocol was developed for labelling cells with SPIO for clinical cell tracking studies. The effects of SPIO-labelling on cell viability and function were assessed in vitro. A phased-dosing protocol was used to establish the safety of intravenous administration of SPIO-labelled cells in healthy volunteers. The feasibility of imaging cells at a target site in vivo following local or systemic administration was assessed. Tracking of SPIO-labelled cells to a target site was investigated by inducing an iatrogenic inflammatory focus in the skin of the anterior thigh of healthy volunteers, following which autologous SPIO-labelled cells were administered and their accumulation was assessed using MRI scanning and histology of skin biopsies. Results Robust and semi-quantitative data acquisition and image analysis methodology was developed for the assessment of SPIO accumulation in tissues. In patients with AAA, histological analysis of aortic wall tissue samples confirmed USPIO accumulation in areas of cellular inflammation. USPIO-enhanced MRI detected aortic wall inflammation and mural USPIO uptake was associated with a 3-fold higher aneurysm expansion rate. Human mononuclear cells were labelled with SPIO under GMP compliant conditions without affecting cell viability or function. Both local and intravenous administration of SPIO-labelled cells was safe and cells were detectable in vitro and in vivo using a clinical MRI scanner. SPIO-labelled cells tracked to a focal iatrogenic inflammatory focus following intravenous administration in humans and were detectable on MRI scanning and histological examination of skin biopsies. Conclusions SPIO contrast agents have an extensive range of potential clinical applications. USPIO uptake in the wall of AAA appears to identify cellular inflammation and predict accelerated aneurysm expansion. This is therefore a promising investigative tool for stratifying the risk of disease progression in patients with AAA, and may also be considered as a biomarker for response to novel pharmacological agents. The ability to label cells for non-invasive cell tracking studies would facilitate the further development of novel cell-based therapies and would enable assessment of dynamic inflammatory processes through inflammatory cell tracking.

M.Cur. / The natural progress of an abdominal aortic aneurysm is enlargement and rupture. The incidence of abdominal aortic aneurysms has increased in the past 30 years and up to 50% of the patients with untreated aneurysms will die due to rupture within 5 years. Open surgery is effective in the prevention of rupture and can be performed with a mortality of 2 -5% in most cases. However, patients with aneurysms are generally older and have associated medical co-morbidities, which increase the risk in surgical intervention. In view of these associated risks with open surgery for abdominal aorta aneurysm repair, a less invasive option such as endoluminal stent-grafts, are often preferred. This new, less invasive technique with Parodi as pioneer has several advantages for patients, the greatest being the reduction in peri-operative risks of aneurysm repair. As in all new procedures, this new intervention sets specific requirements for quality peri-operative nursing. Within the legal-ethical framework of nursing there is no room for random nursing, and we as nurses must turn to protocols and standards applicable to quality nursing, and in effect the quality assurance process. Quality nursing care delivery to the patient remains the ideal of each nurse. The endovascular repair of abdominal aortic aneurysms, although less invasive, is still associated with major morbidity and mortality. The potential for complications is a reality. Complications are mainly systemic and/or procedure related. The reality of these complications affects the quality of nursing. Finally, the need to accommodate this problem requires that protocol/standards are established for the nursing of the patient with an endoluminal repair of an abdominal aortic aneurysm by means of an endovascular stent-graft. The following question can be asked in view of the above arguments and problem statement: How must these patients be nursed peri-operatively to ensure quality nursing care? The aim of this study is to compile protocol/standards for quality nursing of patients with an erldovascular stent-graft repair of an abdominal aortic aneurysm in a Coronary Intensive Care Unit in a private hospital in Cape Town.

TEVAR has been used extensively to treat TBAD. The principle of treatment involve placement of a stent graft in the true lumen to cover the primary tear, thereby excluding the false lumen. Success depends on a combination of factors: reduction of false lumen pressure and perfusion, thrombosis of the false lumen, and remodeling of the aorta leading to eventual healing. The long-term goals are to prevent continuous growth of the false lumen, reinterventions, and aneurysm rupture. The success of TEVAR depends on a combination of factors, including the blood flow and pressure in the two aortic lumens, and remodeling is a dynamic process. Much controversy exists regarding the ideal timing of TEVAR, its efficacy in effecting complete false lumen exclusion, the long-term durability of the repair, and the fate of the aortic size. The objective of this thesis is to examine the morphological and hemodynamic changes within the aortic lumens after TEVAR, using a combination of ex-vivo animal models and computational tomography analysis. The residual pressure of the true and false lumens in TBAD models was studied. Volumetric analyses of CT scan of patients were compared. The ultimate goals are to determine if it is beneficial to treat type B dissections early, and to determine long-term morphological results. In ex-vivo hemodynamic study, 28 fresh porcine aortas models were created to simulate three different pathological scenarios of TBAD: model A represented pre-treated TBAD; model B represented post-treated TBAD with patent false lumen; and model C represented chronic stage of post-treated TBAD with false lumen thrombosis. True lumen and false lumen pressure differences were compared between the three models. Pressure effect was successfully reduced by 30% in model C in comparison with the other two models. No hemodynamic parameters were significantly different between model A and model B. Aortic remodeling parameters were volumetrically analyzed and compared between two groups of patients who underwent endo-grafting for uncomplicated TBAD (group A) and dissecting aneurysms (group B). Modern DIOCM processing workstations and software were used to reconstruct thoracic aorta with serial CT scans. The true lumen, false lumen, thrombus and aortic size were measured volumetrically. Stent graft migration and area of inlet and outlet were also quantified. There were progressive migration and continuous expansion of the stent graft on patients in both groups. Favorable aortic remodeling was observed in most. One fourth of all patients demonstrated aortic volume increase at 36 months. However, there was no difference between group A and group B in terms of stent graft re-shaping and aortic remodeling. In conclusion, Aortic remodeling after TEVAR in treating TBAD is a continuous process. There were no significant differences between chronic dissections and dissecting aneurysms in all morphological parameters. Treating chronic dissections before aneurysm formation does not seem to have a morphologic advantage. Sealing of primary entry tear with introducing thrombosis could significantly reduce false lumen pressure. However, the remaining pressure accumulations should be considered to reduce by further excluding distal reentry tears in those patients who undergo progressive false lumen expansion after TEVER. / published_or_final_version / Surgery / Doctoral / Doctor of Philosophy

Abdominal Aortic Aneurysms (AAA) are amongst the top ten most common cause of death in those over 55 years of age. The disease is usually asymptomatic, often being diagnosed incidentally. Once diagnosed, elective repair of an AAA results in excellent long-term survival with a 3-5% operative mortality. However, up to one half of patients present with ruptured aneurysms, a complication that carries an 80% mortality in the community, and of those reaching hospital, a 50% mortality. Clearly early diagnosis and treatment results in improved survival. Screening for AAA, with ultrasound, would detect aneurysms early, prior to rupture. However, debate continues over the cost effectiveness of population based screening programmes. The identification of a sub-population at a higher risk of developing AAA would increase the yield of a screening prograrmne. A number of populations have been examined, none of which have received international acceptance. About 20% of patients with an AAA have a family history of an aneurysm. The disease is also considered to be a disease of Caucasians, both facts suggesting a strong genetic component to the disease. Perhaps a genetically identified sub-population at a high risk of developing an AAA would prove to be an ideal population for screening. This thesis examines the incidence of aneurysms and the family histories of patients with AAA in the Otago region of New Zealand. Almost twenty percent of the population has a family history of AAA. DNA was collected from each of these patients for genetic analysis. The population was divided into familial AAA and non-familial AAA for the purpose of genetic analysis and compared to a control population. AAA is believed to be a disease of Caucasians; a non-Caucasian population with a low incidence of AAA may prove to be a good control population for genetic studies. A literature review demonstrated a higher incidence of AAA in Caucasians than other ethnic groups and within Caucasians a higher incidence in patients of Northern European origin. The incidence was low in Asian communities, even in studies involving of migrant Asian populations. The New Zealand Maori are believed to have originated from South East Asia, therefore could be expected to have a low incidence of AAA and would make an ideal control population for genetic studies. A pilot study was undertaken to examine the incidence of AAA in the New Zealand Maori. The age standardised incidence of AAA proved to be at least equal in Maori to non-Maori, with a more aggressive form of the disease in Maori, manifesting with a younger age at presentation and a higher incidence of ruptured aneurysms at diagnosis. It is well known that at the time of surgery, an AAA

Orientador: Evandro Pinto da Luz de Oliveira / Tese (doutorado) - Universidade Estadual de Campinas. Faculdade de Ciencias Medicas / Made available in DSpace on 2018-08-15T07:57:17Z (GMT). No. of bitstreams: 1 ChaddadNeto_FeresEduardoAparecido_D.pdf: 73496991 bytes, checksum: 1ed841dc2b8fa51a8c132cb82f523160 (MD5) Previous issue date: 2010 / Resumo: A craniotomia pterional é o acesso cirúrgico mais utilizado na prática neurocirúrgica atual. É utilizada para abordar a maior parte dos aneurismas da circulação anterior e lesões tumorais envolvendo a região supra-selar e parte das estruturas da fossa anterior e média. No entanto, se caracteriza como sendo um acesso limitado para as lesões que envolvem a maior parte do lobo temporal, o assoalho da fossa média do crânio e o complexo da artéria basilar. Para tanto, foram desenvolvidas as craniotomias pré-temporal e orbitozigomática. No entanto a literatura é ainda relativamente carente quanto ao estudo do posicionamento exato da cabeça para a melhor abordagem de cada patologia, em particular. Esse trabalho tem por objetivo estudar o melhor posicionamento da cabeça para a realização das craniotomias mencionadas, visando a melhor exposição de cada lesão em particular / Abstract: The pterional approach is the most applied neurosurgical access in the customized practice nowadays. It is used for approaching most of the anterior circulation aneurysms and tumors involving the anterior and the middle cranial space. However, it is considered a limited approach to some pathologies involving the temporal lobe, the middle cranial space floor and the basilar artery complex region. As a result, the orbitozygomatic and the pretemporal craniotomies developed since it was necessary to enlarge such access to the temporal area. However, there is not a systematic evaluation of head positioning study about the best approach to each specific pathology. This study aims to demonstrate the best way to position the head according to each specific pathology, in order to offer a better surgical visualization by using the most appropriated craniotomy / Doutorado / Neurologia / Doutor em Ciências Médicas

Iliac artery aneurysms are considered rare and difficult to detect and treat. Prompt diagnosis and timely intervention are essential, because the incidence of rupture is as high as 50%. The reported mortality rate for patients who undergo surgery for ruptured iliac artery aneurysm ranges from 50% to 70%. This study developed an in-vitro mechanical model of an iliac artery aneurysm to verify the accuracy of computer simulation software. Both the in vitro model and the in silico model can be used for further research to develop better treatment technology. This study also looks at the different types of iliac artery aneurysms, risk factors that contribute to the development of an iliac artery aneurysms, and current treatment options.