L'utilisation de filtres plissés dans le domaine du traitement de l'air est extrêmement fréquente en raison de leur simplicité d'utilisation et de maintenance. Néanmoins, au cours du colmatage, la perte de charge augmente considérablement avec le dépôt de particules. Par conséquent le débit de filtration n'est plus maintenu et une détérioration des médias peut se produire. Il est essentiel de caractériser cette évolution en fonction des conditions opératoires pour mieux concevoir ces équipements. Les travaux ont consisté en une étude expérimentale de l'influence des conditions opératoires sur la géométrie du dépôt par des observations en Tomographie d'Émission MonoPhotonique. Une approche numérique a consisté, dans un premier temps, en une étude de la perméabilité de médias bien caractérisés afin de valider le code GeoDict. Dans un deuxième temps, une étude de la vitesse de l'air a été entreprise sur les médias plissés. La confrontation des résultats numériques avec les données expérimentales nous a permis une validation du code dans les gammes de propriétés des médias et de vitesses typiques. Concernant les médias bimodaux, l'acquisition rapide de données a permis de tester différentes corrélations analytiques afin de classifier les modèles existants d'une manière qui facilite leur utilisation. Si les résultats expérimentaux obtenus sur la localisation du dépôt préférentiel initial dans les filtres plissés sont encourageants, notamment vis-à-vis des simulations d'écoulement réalisées avec GeoDict, ceux issus des acquisitions sur les filtres précolmatés sont à prendre avec prudence et suggèrent d'apporter un certain nombre d'amélioration à notre technique / Pleated filters are widely used in air treatments because of the advantageous effective surface to overall dimension ratio they offer. Their major drawback though resides in their reduced lifetime which still needs to be controlled. Indeed, when clogging, the pressure drop considerably increases, the filtration flow is then no longer maintained which might lead to the deterioration of the media. It is then crucial to characterize the evolution of the pressure drop under operating conditions in order to best design these equipments. Part of our work consisted in studying how the operating conditions influence the geometry of the deposit. To do so, we used Single-Photon Emission Computed Tomography (SPECT), a non-destructive imaging technique that keeps intact the particle structuring. The visualization of aerosol deposit at the beginning of the filtration process allows observing preferential particle deposition on the whole height of the pleat. A numerical approach was used to study the permeability of bimodal fibrous media and we experimentally studied the local velocity as well as the biphasic flow inside pleated filter media. Comparison between experiments and simulations allowed us to validate the Geodict code for a wide range of media properties and velocities. Regarding bimodal fibrous media, the fast data acquisition has allowed testing several existing models which resulted in classifying them in a unique way. If the experimental results on the initial deposition in pleated filters are encouraging, those related to beforehand clogging point to several improvements regarding the technique we used

INTRODUÇÃO: A avaliação do mediastino quanto à presença de metástases linfonodais é importante na escolha do tratamento dos pacientes com câncer de pulmão de não pequenas células. Apesar da tomografia computadorizada ser o exame de imagem de escolha no estadiamento do câncer de pulmão, tem limitações conhecidas quanto à avaliação dos linfonodos regionais. O objetivo deste trabalho é avaliar a acurácia do SPECT/TC utilizando o radiofármaco 99mTc-sestamibi no estadiamento linfonodal do mediastino em pacientes com diagnóstico de carcinoma de pulmão de não pequenas células e candidatos a tratamento cirúrgico. MÉTODOS: Foi realizada coleta prospectiva de dados de 41 pacientes entre dezembro de 2006 a fevereiro de 2009. Os pacientes foram submetidos à tomografia computadorizada de tórax e ao SPECT/TC com 99mTc-sestamibi no prazo máximo de 30 dias antes da cirurgia. O SPECT/TC foi considerado positivo quando havia captação no mediastino e a tomografia de tórax, quando havia linfonodos maiores do que 10 mm no menor eixo. Os resultados da interpretação do SPECT/TC com sestamibi e da TC de tórax foram comparados aos encontrados na patologia, definido como método padrão ouro. RESULTADOS: O SPECT/TC identificou de maneira correta seis dos 19 casos com envolvimento dos linfonodos hilares e um dos sete casos com metástases ganglionares no mediastino pela patologia. Os valores de sensibilidade, especificidade, valores de predição positivo e negativo para o 99mTc-sestamibi SPECT/TC na avaliação do hilo foram respectivamente de: 31,6%, 95,5%, 85,7% e 61,8% e para o mediastino de 14,3%, 97,1%, 50% e 84,6%. A tomografia de tórax encontrou sensibilidade para a análise dos linfonodos hilares e mediastinais de 47,4% e 57,1%, especificidade de 95,5%, e 91,2%, valores de predição positivo de 90% e 57,1% e negativo de 67,7% e 91,2%, respectivamente. CONCLUSÃO: Nos pacientes com câncer de pulmão de não pequenas células com doença inicial e ressecável o SPECT/TC com 99mTc-sestamibi no estadiamento linfonodal do mediastino apresentou baixa sensibilidade e acurácia, apesar da alta especificidade. O SPECT/TC não adicionou informações relevantes à TC de tórax, que poderiam justificar o seu emprego no estadiamento pré-operatório do carcinoma de pulmão de não pequenas células / INTRODUCTION: The proper nodal staging of non-small cell lung cancer is important to choose the best treatment modality. Although CT is the first-line imaging test for primary staging of lung cancer, it is well known its limitations on mediastinum nodal staging. The aim was to evaluate the accuracy of SPECT/CT using 99mTc-sestamibi in the nodal staging of patients with non-small cell lung cancer and potential candidates towards surgical treatment. METHODS: A prospective data collection of 41 patients was conducted from December 2006 to February 2009. The patients underwent chest CT and SPECT/CT with 99mTc-sestamibi within 30 days interval before surgery. SPECT/CT was considered positive when there was focal uptake of sestamibi in the mediastinum and CT scan when there was lymph nodes larger than 10 mm in short axis. The results of SPECT/CT and CT were correlated with pathology findings after surgery. RESULTS: SPECT/CT correctly identified six of 19 cases with involvement of hilar lymph nodes and one of seven cases with nodal metastases in the mediastinum. The sensitivity, specificity, positive and negative predictive value for 99mTc-sestamibi SPECT/CT in the assessment of the hilum were respectively: 31.6%, 95.5%, 85.7% and 61.8% and for the mediastinum 14.3%, 97.1%, 50% and 84.6%. Chest tomography showed a sensitivity of hilar and mediastinal lymph nodes of 47.4% and 57.1%, specificity of 95.5% and 91.2%, positive predictive value of 90% and 57.1% and negative predictive value of 67.7% and 91.2%, respectively. CONCLUSION: SPECT/CT with 99mTc-sestamibi showed very low sensitivity and accuracy for nodal staging of patients with non-small cell cancer despite its high specificity. Moreover, the performance of SPECT/CT added no relevant information compared to CT that could justify its use in the routine preoperative staging of non-small cell lung carcinoma

INTRODUÇÃO: A avaliação do mediastino quanto à presença de metástases linfonodais é importante na escolha do tratamento dos pacientes com câncer de pulmão de não pequenas células. Apesar da tomografia computadorizada ser o exame de imagem de escolha no estadiamento do câncer de pulmão, tem limitações conhecidas quanto à avaliação dos linfonodos regionais. O objetivo deste trabalho é avaliar a acurácia do SPECT/TC utilizando o radiofármaco 99mTc-sestamibi no estadiamento linfonodal do mediastino em pacientes com diagnóstico de carcinoma de pulmão de não pequenas células e candidatos a tratamento cirúrgico. MÉTODOS: Foi realizada coleta prospectiva de dados de 41 pacientes entre dezembro de 2006 a fevereiro de 2009. Os pacientes foram submetidos à tomografia computadorizada de tórax e ao SPECT/TC com 99mTc-sestamibi no prazo máximo de 30 dias antes da cirurgia. O SPECT/TC foi considerado positivo quando havia captação no mediastino e a tomografia de tórax, quando havia linfonodos maiores do que 10 mm no menor eixo. Os resultados da interpretação do SPECT/TC com sestamibi e da TC de tórax foram comparados aos encontrados na patologia, definido como método padrão ouro. RESULTADOS: O SPECT/TC identificou de maneira correta seis dos 19 casos com envolvimento dos linfonodos hilares e um dos sete casos com metástases ganglionares no mediastino pela patologia. Os valores de sensibilidade, especificidade, valores de predição positivo e negativo para o 99mTc-sestamibi SPECT/TC na avaliação do hilo foram respectivamente de: 31,6%, 95,5%, 85,7% e 61,8% e para o mediastino de 14,3%, 97,1%, 50% e 84,6%. A tomografia de tórax encontrou sensibilidade para a análise dos linfonodos hilares e mediastinais de 47,4% e 57,1%, especificidade de 95,5%, e 91,2%, valores de predição positivo de 90% e 57,1% e negativo de 67,7% e 91,2%, respectivamente. CONCLUSÃO: Nos pacientes com câncer de pulmão de não pequenas células com doença inicial e ressecável o SPECT/TC com 99mTc-sestamibi no estadiamento linfonodal do mediastino apresentou baixa sensibilidade e acurácia, apesar da alta especificidade. O SPECT/TC não adicionou informações relevantes à TC de tórax, que poderiam justificar o seu emprego no estadiamento pré-operatório do carcinoma de pulmão de não pequenas células / INTRODUCTION: The proper nodal staging of non-small cell lung cancer is important to choose the best treatment modality. Although CT is the first-line imaging test for primary staging of lung cancer, it is well known its limitations on mediastinum nodal staging. The aim was to evaluate the accuracy of SPECT/CT using 99mTc-sestamibi in the nodal staging of patients with non-small cell lung cancer and potential candidates towards surgical treatment. METHODS: A prospective data collection of 41 patients was conducted from December 2006 to February 2009. The patients underwent chest CT and SPECT/CT with 99mTc-sestamibi within 30 days interval before surgery. SPECT/CT was considered positive when there was focal uptake of sestamibi in the mediastinum and CT scan when there was lymph nodes larger than 10 mm in short axis. The results of SPECT/CT and CT were correlated with pathology findings after surgery. RESULTS: SPECT/CT correctly identified six of 19 cases with involvement of hilar lymph nodes and one of seven cases with nodal metastases in the mediastinum. The sensitivity, specificity, positive and negative predictive value for 99mTc-sestamibi SPECT/CT in the assessment of the hilum were respectively: 31.6%, 95.5%, 85.7% and 61.8% and for the mediastinum 14.3%, 97.1%, 50% and 84.6%. Chest tomography showed a sensitivity of hilar and mediastinal lymph nodes of 47.4% and 57.1%, specificity of 95.5% and 91.2%, positive predictive value of 90% and 57.1% and negative predictive value of 67.7% and 91.2%, respectively. CONCLUSION: SPECT/CT with 99mTc-sestamibi showed very low sensitivity and accuracy for nodal staging of patients with non-small cell cancer despite its high specificity. Moreover, the performance of SPECT/CT added no relevant information compared to CT that could justify its use in the routine preoperative staging of non-small cell lung carcinoma

Thesis (Ph. D.)--Ohio State University, 2006. / Available online via OhioLINK's ETD Center; full text release delayed at author's request until 2007 Jun 16

Thesis (D.Tech.: Radiography)-Dept. of Radiography, Durban Institute of Technology, 2006 xxiii, 166 leaves / The purpose of this study was to evaluate 99mTc- methoxyisobutylisonitrile (MIBI) imaging, in terms of sensitivity and specificity, for non invasively detecting extracutaneous involvement of Kaposi’s sarcoma (KS) and for differentiating pulmonary infection from malignancy in acquired immunodeficiency syndrome (AIDS) patients before and after treatment. Current investigations are invasive.

Thesis (D.Tech.: Radiography)-Dept. of Radiography, Durban Institute of Technology, 2006 xxiii, 166 leaves / The purpose of this study was to evaluate 99mTc- methoxyisobutylisonitrile (MIBI) imaging, in terms of sensitivity and specificity, for non invasively detecting extracutaneous involvement of Kaposi’s sarcoma (KS) and for differentiating pulmonary infection from malignancy in acquired immunodeficiency syndrome (AIDS) patients before and after treatment. Current investigations are invasive.

Abstract In the Nordic countries, event-free survival (EFS) exceeds 80% in certain groups of children treated for acute lymphoblastic leukaemia (ALL). With the improved cure rates, however, there are more children suffering from neurological late effects, especially due to therapy directed at the central nervous system (CNS). The aim of this study is to examine the changes taking place in the nervous system after leukemia treatment and to evaluate the role of treatment in these changes in patients and in an animal model. Twenty-seven ALL survivors and healthy controls were examined by means of motor evoked potentials (MEPs). ALL survivors were also examined clinically. The children with ALL continued to show decreased motor nerve conduction in the peripheral nerves, but not within the CNS, five years after the cessation of treatment. Clinical neurological findings were obtained in 33% of the cases. The MEP results indicated reversibility of the motor injury due to CNS effects. Nineteen patients underwent perfusion magnetic resonance imaging (MRI) at the cessation of treatment or 4-8 years after the treatment. Seventeen of them also underwent single-photon emission computed tomography (SPECT). The studies showed small perfusion defects in SPECT, which were not visible by perfusion MRI. Methotrexate (Mtx) neurotoxicity was studied in a swine model using functional MRI, brain perfusion SPECT, iodine-123 labelled 2β-carbomethoxy-3β-(4-iodophenyl) tropane ([123I]β-CIT) SPECT and whole-hemisphere autoradiography with [125I]β-CIT in ten Mtx-treated animals and five control animals. Mtx-related changes in the brain could be detected as reduced or negative blood-oxygen-level-dependent (BOLD) responses to somatosensory activation in BOLD contrast MRI, which indicates changes in flow metabolism coupling. Perfusion defects in brain SPECT were seen in the Mtx group and the control group, which suggests that the perfusion defects seen in brain SPECT are probably multifactorial. The change in dopamine transporter (DAT) density in the Mtx group was not different from that in the controls. The abnormalities in nerve conduction after treatment in survivors of ALL were partly reversible years after the treatment. The patients had perfusion defects in SPECT imaging which were not seen in perfusion MRI. The clinical significance of these defects remains obscure. The animal model suggested perfusion defects to be multifactorial.

No description available.

Bone is a remarkable multifunctional tissue with the ability to regenerate and remodel without generating any scar tissue. However, bone loss due to injury or diseases can be a great challenge and affect the patient significantly. Autologous bone grafting is commonly used throughout the world. Autograft both fills the void and is bone inductive, housing the particular cells that are needed for bone regeneration. However, a regenerative complement to autograft is of great interest as the use of biomaterials loaded with bioactive molecules can avoid donor site morbidity and the problem of a limited volume of material. Two such regenerative products that utilise bone morphogenetic protein (BMP)-7 and -2 have been used for more than a decade clinically. Unfortunately, several side effects have been reported, such as severe swelling due to inflammation and ectopic bone formation. Additionally, the products require open surgery and use of supra physiological doses of the BMPs due to poor localisation and retention of the growth factor. The purpose of this thesis was to harness the strong inductive capacity of the BMP-2 by optimising the carrier of this bioactive protein, thereby minimising the side effects that are associated with the clinical products and facilitating safe and localised bone regeneration. We focused on an injectable hyaluronan-based carrier developed through polymer chemistry at the University of Uppsala. The strategy was to use the body’s own regenerative pathway to stimulate and enhance bone healing in a manner similar to the natural bone-healing process. The hyaluronan-based carrier has a similar composition to the natural extracellular matrix and is degraded by resident enzymes. Earlier studies have shown improved properties when adding hydroxyapatite, a calcium phosphate that constitutes the inorganic part of the bone matrix. In Paper I, the aim was to improve the carrier by adding other forms of calcium phosphate. The results indicated that bone formation was enhanced when using nano-sized hydroxyapatite. In Paper II, we discovered the importance of crushing the material, thus enhancing permeability and enlarging the surface area. We wished to further develop the carrier system, but were lacking an animal model with relatively high throughput, facilitated access, paired data, and we were also committed to the 3Rs of refinement, reduction, and replacement. To meet these challenges, we developed and refined an animal model, and this is described in Paper III. In Paper IV, we sought to further optimise the biomaterial properties of the hydrogel through covalent bonding of bisphosphonates to the hyaluronan hydrogel. This resulted in exceptional retention of the growth factor BMP-2. In Paper V, SPECT/PET/µCT was combined as a tri-modal imaging method to allow visualisation of the biomaterial’s in situ action, in terms of drug retention, osteoblast activity and mineralisation. Finally, in Paper VI the correlation between existing in vitro results with in vivo outcomes was observed for an array of biomaterials. The study identified a surprisingly poor correlation between in vitro and in vivo assessment of biomaterials for osteogenesis.

O presente estudo comparou o fluxo sanguíneo cerebral regional avaliado através da tomografia por emissão de fóton simples (SPECT) de pacientes com crises epilépticas temporais com pacientes com crises não epilépticas psicogênicas (CNEP). Todos os SPECT foram realizado no período ictal, tendo as CNEP sido induzidas por métodos sugestivos e de hipnose. Os grupos de pacientes com epilepsia e CNEP foram ainda comparados com um terceiro grupo, denominado grupo de sujeitos saudáveis. As comparações dos SPECT foram feitas através da análise visual (radiologista cego ao estudo) e semiquantitativa pelo programa Statistical Parametric Mapping (SPM). Os objetivos do estudo foram: (1) estabelecer a sensibilidade e a especificidade do SPECT ictal para o diagnóstico diferencial entre CNEP e crises epilépticas parciais complexas em pacientes com epilepsia do lobo temporal, em comparação com o VEEG associado a técnicas de hipnose; (2) avaliar através da análise quantitativa voxel a voxel do SPECT as alterações de perfusão cerebral dos pacientes com CNEP em relação aos pacientes com epilepsia, dos pacientes com CNEP em relação a um grupo controle de sujeitos normais e dos pacientes com epilepsia em relação a um grupo controle de sujeitos saudáveis. Foram estudados 30 pacientes no grupo com CNEP, 22 pacientes no grupo com epilepsia e 29 sujeitos saudáveis. Os resultados mostram que os SPECT ictais dos pacientes do grupo CNEP foram diferentes dos SPECT ictais dos pacientes com epilepsia. Na análise visual o SPECT ictal apresentou sensibilidade de 50% e especificidade de 91% para o diagnóstico de CNEP . Na análise comparativa voxel a voxel entre os grupos os resultados revelaram que: (a) houve aumento de perfusão cerebral em lobo temporal esquerdo e tronco cerebral nos pacientes do grupo epilepsia em relação ao grupo controle normal; (b) houve diminuição de perfusão cerebral no lobo frontal esquerdo e córtex anterior do cíngulo nos pacientes do grupo epilepsia em relação ao grupo controle normal; (c) houve aumento de perfusão cerebral no giro do cíngulo e precuneus á direita nos pacientes do grupo CNEP em relação ao grupo epilepsia; (d) houve diminuição perfusão cerebral em amígdala direita nos pacientes do grupo CNEP em relação ao grupo epilepsia; (e) houve aumento de perfusão cerebral na cauda do núcleo caudado esquerdo, giro précentral esquerdo e tálamo direito nos pacientes do grupo CNEP em relação ao grupo controle normal. Desta forma, após a análise estatística dos resultados concluímos que na análise visual, um SPECT ictal positivo em um paciente com suspeita de CNEP não confirma nem afasta tal suspeita, já que a sensibilidade do método foi baixa (50%). Na análise visual, um SPECT ictal negativo em um paciente com suspeita de CNEP afasta a possibilidade de epilepsia do lobo temporal com 91% de acerto (especificidade do método). O resultado da análise visual do SPECT ictal de CNEP revelou valor de sensibilidade abaixo do encontrado na literatura, e valor de especificidade superior ao encontrado na literatura. A análise quantitativa dos SPECT de crise epiléptica em comparação com os de sujeitos saudáveis em repouso, mostrou concordância com a análise visual em relação à lateralidade. Tal comparação revelou ainda ativação de áreas compatíveis com o que se encontra na literatura. A análise quantitativa dos SPECT ictais do grupo CNEP em comparação com os do grupo epilepsia revelou ativação de estruturas cerebrais posteriores (precuneus e giro cíngulo), não havendo comparação semelhante na literatura. A análise quantitativa dos SPECT ictais do grupo CNEP em comparação com os de sujeitos saudáveis em repouso, mostrou ativação do sistema estriatotalamocortical, achado em concordância com a literatura. A ativação do sistema estriatotalamocortical nos pacientes com CNEP mostrou ser um correlato neuroanatômico clinicamente relevante, com forte associação estatística. / The study compared regional cerebral blood flow assessed by positron emission tomography single photon (SPECT) in patients with temporal lobe epilepsy and patients with psychogenic nonepileptic seizures (PNES). All SPECT were performed in the ictal period, PNES having been induced by and suggestive methods of hypnosis. The groups of patients with epilepsy and PNES were compared with a third group, called group of healthy subjects. SPECT comparisons were made by visual analysis (radiologist blinded to the study) and semiquantitative analysis by Statistical Parametric Mapping (SPM). The study objectives were: (1) to establish the sensitivity and specificity of ictal SPECT for the differential diagnosis between PNES and complex partial seizures in patients with temporal lobe epilepsy, compared with VEEG associated with hypnosis techniques, (2) to assess by quantitative analysis of SPECT voxel to voxel changes in cerebral perfusion of patients with PNES compared to patients with epilepsy, patients with PNES compared to a control group of normal subjects and patients with epilepsy compared to a control group of healthy subjects. We studied 30 patients in the PNES group, 22 patients in the group with epilepsy and 29 healthy subjects. The results show that ictal SPECT of patients in the PNES group were different from the ictal SPECT of patients with epilepsy. The visual analysis of ictal SPECT had a sensitivity of 50% and specificity of 91% for the diagnosis of PNES. In the voxel voxel comparative analysis between the groups the results showed that: (a) increased cerebral perfusion in the left temporal lobe and brain stem in patients of epilepsy group compared to normal control group, (b) a decrease in cerebral perfusion in the left frontal lobe and anterior cingulate cortex in patients of epilepsy group compared to normal control group, (c) increased cerebral perfusion in the cingulate gyrus and precuneus in the right group of PNES patients compared to epilepsy group, (d) decreased cerebral perfusion in the right amygdala in patients PNES group compared to the epilepsy group, (e) increased cerebral perfusion in the left tail of the caudate nucleus, left pre-central gyrus and right thalamus in patients in the PNES group compared to group normal control. Therefore, after statistical analysis of the results we conclude that in visual analysis, a positive ictal SPECT in a patient with suspected PNES neither confirms nor removes the suspicion, since the sensitivity was low (50%). In visual analysis, a negative ictal SPECT in a patient with suspected PNES rules out the possibility of temporal lobe epilepsy with 91% accuracy (specificity of the method). The result of visual analysis of ictal SPECT of PNES revealed sensitivity value below that found in the literature and specificity value higher than that found in the literature. The quantitative analysis of SPECT of seizures compared with those of healthy subjects at rest, showed agreement with visual analysis in relation to laterality. This comparison also revealed activation in areas consistent with that found in the literature. The quantitative analysis of SPECT ictal PNES group compared with the epilepsy group showed activation of posterior brain structures (cingulate gyrus and precuneus), with no similar comparison in the literature. The quantitative analysis of SPECT ictal PNES group compared to healthy subjects at rest, showed activation of the estriatotalamocortical, a finding in agreement with the literature. The activation of the estriatotalamocortical circuit in patients with PNES proved to be a neuroanatomical correlate clinically relevant, with strong statistical association