Molecular magnetic resonance imaging (MRI) methods have the potential to provide detailed information regarding cellular and molecular processes at small scales within the human body. Nuclear signals from chemical samples can be probed using specialised MRI techniques, to highlight molecular contrast from particular enzymes or metabolites. The aim of the work described in this thesis is to investigate both exogenous and endogenous contrast mechanisms using fluorine MRI and chemical exchange saturation transfer (CEST) respectively, in order to detect molecular changes in vitro. Initial theoretical work investigates the factors which affect fluorine MRI signals and provides a theoretical framework to determine the sensitivity of such experiments. A novel paramagnetic fluorine sensor to detect enzyme activity is then characterised using high field nuclear magnetic resonance (NMR), showing 60 to 70–fold increases in T1 relaxation values upon enzyme interaction. The effects on the fluorine lineshape from varying sample temperature and solvent were investigated. The possibility of imaging is demonstrated, but further investigations using the theoretical framework found pre–clinical implementation of the sensor is limited by the achievable experimental sensitivity. Efforts then focussed on CEST molecular methods, which are not limited by sensitivity. A protocol is developed to target amide protons in an in vitro cancer cell model, with parameters optimised following simulation of the expected contrast. Analysis of CEST results were aided through use of a support vector machine (SVM) to distinguish group differences between cancer cells and control samples. A linear classifier was found to be suitable to discriminate between samples.

Made available in DSpace on 2015-07-22T20:49:44Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-04-29. Added 1 bitstream(s) on 2015-08-11T03:25:40Z : No. of bitstreams: 1 Publico-058.pdf: 1174030 bytes, checksum: 6102ccff4fb9134a645e0915a421a08f (MD5) / O registro de informações do paciente é um instrumento de grande importância na área médica. O processo de geração de laudos em radiologia pode ser dinamizado e melhorado com a utilização de sistemas eletrônicos baseados em tecnologias de informação e comunicação que podem trazer benefícios como o aumento de produtividade e redução de tempo e custo. Esta pesquisa comparou tempos de geração e digitação de laudos entre um sistema eletrônico, que possibilitou ao médico radiologista gravar seus laudos gerados por voz em formato digital e o sistema tradicional no qual o radiologista escreve o laudo a mão. Para realização da pesquisa foi necessário modelar e construir o sistema eletrônico proposto para fins de comparação com o tradicional já existente. Por meio de formulários, radiologistas e digitadores anotaram os tempos de geração e digitação dos laudos nos dois sistemas. Comparadas as médias entre eles, o sistema eletrônico apresentou redução de 20% (p=0,0410) do tempo médio de geração do laudo em comparação com o sistema tradicional. Por outro lado, o sistema tradicional foi mais eficiente em relação ao tempo de digitação já que a média de tempo do sistema eletrônico foi três vezes maior (p<0,0001). / The patient medical record is extremely important in medicine. The radiology report generation process can be improved using electronic models based in communication and information technologies that can improve productivity, reduce time and cost. This research compares generation and transcription times of the radiology report between a radiology information system where the radiologist can record radiology reports by voice in digital format and the traditional system in which the radiologist writes the radiology reoport by hands. To conduct the study was necessary to model and construct the electronic system for comparison with the existing traditional system. Using forms, radiologists and transcriptionists register the generation and transcription times in both systems. Comparign the averages, the electronic system reduced 20% (p=0,0410) the generation average time of radiology report compared with traditional system. Moreover, the traditional system was more efficient in relation to transcription time whereas the average time of eletronic system was three times bigger (p<0,0001). / TEDE

Resumo: O Diabetes mellitus (DM) é uma alteração metabólica que pode comprometer a estabilidade do implante dentário devido a influência no tecido ósseo. O objetivo do estudo foi avaliar o efeito do Diabetes Mellitus e da insulinoterapia na osseointegração estabelecida ao redor de implantes instalados em tíbia de ratos. Foram utilizados 80 ratos Wistar, os quais foram divididos em 4 grupos: controle de 2 meses (C2m), controle de 4 meses (C4m), diabético (D) e insulínico (I). Os implantes de superfície lisa (2,2mmx4mm) foram instalados na tíbia do rato. Após um período de 2 meses para osseointegração, o grupo C2m foi sacrificado. A indução do DM foi realizada com dose única de estreptozotocina (40mg/Kg) pela veia peniana. Os ratos do grupo I receberam insulina subcutânea (8,5 U/dia) e os demais receberam solução salina (0,9%) pela mesma via. Os níveis da glicemia plasmática foram avaliados periodicamente pelo método enzimático da glicose-oxidase. Dois meses após a indução do DM, os grupos C4m, D e I foram sacrificados. A relação do tecido ósseo com o implante foi avaliada pelas análises: radiográfica (subtração radiográfica digital); bioquímica; histométrica e torque de remoção do implante. Os dados das análises radiográfica, bioquímica e histométrica foram comparados nos grupos pelo teste ANOVA, p>0,05. Os dados da análise do torque de remoção foram comparados nos grupos pelo teste Kruskal Wallis e Friedman, p>0,05. Os resultados mostraram que o grupo D apresentou níveis de glicemia plasmática acima de 300mg/dL e significativamente mais alto do que os grupos C4m e I após a indução do DM e esta condição sistêmica foi mantida até o final do experimento. / Abstract: The Diabetes mellitus (DM) is a metabolic disease that can impair the dental implant establishment by bone tissue influence. The aim of this study was evaluate the effect of Diabetes Mellitus (DM) and insulin therapy on osseointegration around dental implants. Eighty implants were placed in 80 tibiae of adult rats. After a healing period of two months, the animals were divided into four groups of 20 animals each and subdivided into 10 rats for removal torque analysis and 10 rats for histometric analysis. Group C2m was sacrificed at this time. DM was induced using 40mg/kg Streptozotocin in a diabetic group (group D) and an insulinic group (group I). During two months, group I received subcutaneous doses of 8.5 UI insulin twice a day. Groups C4m (control of 4months) and D received only saline. After two months, the animals of groups D, I and C4m were sacrificed. The glycemic control of the animals was monitored during the experiment. The relation of bone with implant was evaluated by 18 radiographic (digital subtraction radiography), bioquimic, histometric and removal torque analysis. Data obtained with radiographic, bioquimic and histometric analysis were analyzed and compared by ANOVA test, p>0,05. Data obtained with removal torque analysis were analyzed and compared by Kruskal Wallis and Friedman tests, p>0,05. The glycemic controls were within normal range for groups A, C and I and higher for group D and maintained during experiment. Greater significant values of ALP serum and Ca urinary were determined in group D after DM induction. There was a significant difference in gray shade values in the subtraction image between groups D (123±9) and I (136±5) (p<0.05) on bone formation around the implant while there were no significant differences between control groups A (127±13) and C (133±10) and insulinic group. / Orientador: Gulnara Scaf / Coorientador: Elcio Marcantonio Junior / Banca: Julio César Joly / Banca: Maria Lúcia Rubo Rezende / Banca: Guilherme Monteiro Tosoni / Banca: Marisa Aparecida Cabrini Gabrielli / Doutor

A prototype proton-cone-beam-computed-tomography (PCB-CT) system utilizing a proton radiatiotherapy beam has been developed. The system acquires CT data in the cone-beam geometry. The cone-beam is produced by scattering a 158.6 MeV narrow parallel proton beam on a range modifier in the form of a linear modulating wheel. The wheel is a PMMA propeller of variable thickness that rotates about its axis parallel to the beam line. The energy spectrum generated by the wheel is designed to result in a monotonically decreasing linear signal versus energy deposited in the detector system. Protons are detected by a system using an intensifying screen and CCD digital camera. The PCB-CT scanner measures relative stopping power of protons in 3D with equal resolution in each dimension. It operates at clinically relevant energies and geometries and in this way facilitates proton therapy planning techniques. The Feldkamp-Davis-Kress cone-beam reconstruction algorithm is applied to obtain the proton stopping powers. Calibration of the proton CT projections is performed with the aid of a stack of PMMA plates positioned in front of the intensifying screen. Contrast and spatial resolution of the PCB-CT scan is evaluated from CT reconstructions of a contrast-resolution phantom. Artifacts in the reconstruction due to neutron noise in the detector system are corrected by a subtraction technique. In addition, computer-simulations of proton CT projection data have been performed. For this purpose, a macroscopic proton transport algorithm has been developed. The algorithm derives from the Boltzmann equation. Energy loss is modeled by using experimental energy-range tables for specific materials, while energy deposition is modeled by using a measured dependence of dose on depth in water (the Bragg curve) and the concept of water equivalent thickness (WET). Nuclear collisions are accounted for by the inclusion of the experimental Bragg curve data in water. The small-angle-approximation is assumed in treating the multiple Coulomb scattering (MCS). Limitations of the PCB-CT in characterizing the relative proton stopping power due to the MCS phenomena are examined. A method of removing the MCS artifacts from the projection data is employed to obtain more accurate reconstructed proton stopping powers.

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