Made available in DSpace on 2015-04-14T13:56:33Z (GMT). No. of bitstreams: 1 462943.pdf: 4086036 bytes, checksum: 8b6abefa3b76b3bc43dbf4ca084a593b (MD5) Previous issue date: 2014-08-25 / In clinical practice, PET/CT images are often analyzed qualitatively by visual comparison of tumor lesions and normal tissues uptake; and semi-quantitatively by means of a parameter called SUV (Standardized Uptake Value). To ensure that longitudinal studies acquired on different scanners are interchangeable, and information of quantification is comparable, it is necessary to establish a strategy to harmonize the quantification of SUV. The aim of this study is to evaluate the strategy to harmonize the quantification of PET/CT images, performed with different scanner models and manufacturers. For this purpose, a survey of the technical characteristics of equipment and acquisition protocols of clinical images of different services of PET/CT in the state of Rio Grande do Sul was conducted. For each scanner, the accuracy of SUV quantification, and the Recovery Coefficient (RC) curves were determined, using the reconstruction parameters clinically relevant and available. From these data, harmonized performance specifications among the evaluated scanners were identified, as well as the algorithm that produces, for each one, the most accurate quantification. Finally, the most appropriate reconstruction parameters to harmonize the SUV quantification in each scanner, either regionally or internationally were identified. It was found that the RC values of the analyzed scanners proved to be overestimated by up to 38%, particularly for objects larger than 17mm. These results demonstrate the need for further optimization, through the reconstruction parameters modification, and even the change of the reconstruction algorithm used in each scanner. It was observed that there is a decoupling between the best image for PET/CT qualitative analysis and the best image for quantification studies. Thus, the choice of reconstruction method should be tied to the purpose of the PET/CT study in question, since the same reconstruction algorithm is not adequate, in one scanner, for qualitative and quantitative assessments in different scopes. We concluded that the harmonization strategy of the SUV quantification presented in this paper was effective in reducing the variability of small structures quantification. However, for the comparison of SUV quantification between different scanners and institutions, it is essential that, in addition to the harmonization of quantification, the standardization of the methodology of patient preparation is maintained, in order to minimize the SUV variability due to biological factors. / Na rotina cl?nica, imagens de PET/CT, costumam ser analisadas qualitativamente, mediante a compara??o visual entre a capta??o nos tecidos hipercaptantes e nos tecidos normais; e, semiquantitativamente, por meio de um par?metro denominado SUV (do ingl?s Standardized Uptake Value). Para garantir que estudos longitudinais adquiridos em distintos equipamentos sejam intercambi?veis e informa??es de quantifica??o sejam compar?veis, torna-se necess?rio o estabelecimento de uma estrat?gia de harmoniza??o da quantifica??o do SUV. O objetivo geral deste estudo ? avaliar uma estrat?gia de harmoniza??o da quantifica??o de imagens de PET/CT, realizada com equipamentos de diferentes modelos e fabricantes. Para tanto, foi realizado um levantamento das caracter?sticas t?cnicas do equipamento e dos protocolos de aquisi??o das imagens cl?nicas de distintos servi?os de PET/CT do estado do Rio Grande do Sul. Para cada equipamento, foram determinadas a acur?cia da quantifica??o do SUV e as curvas de Coeficiente de Recupera??o (RC, do ingl?s Recovery Coefficient), utilizando os par?metros de reconstru??o clinicamente dispon?veis e relevantes. A partir desses dados, foram identificadas as especifica??es de desempenho harmoniz?veis dentre os equipamentos avaliados, assim como o algoritmo que produz, em cada equipamento, a quantifica??o mais acurada. Finalmente, foram identificados os par?metros de reconstru??o mais adequados ? harmoniza??o da quantifica??o do SUV em cada equipamento, em ?mbito regional e internacional. Constatou-se que os valores de RC dos equipamentos analisados mostraram-se superestimados em at? 38%, particularmente para objetos de dimens?es maiores do que 17 mm. Estes resultados mostram a necessidade de uma otimiza??o, mediante a modifica??o dos par?metros de reconstru??o utilizados e at? mesmo da mudan?a do algoritmo de reconstru??o utilizado em cada equipamento. Observou-se que existe uma dissocia??o entre a melhor imagem para an?lise qualitativa e a melhor imagem para quantifica??o dos estudos de PET/CT. Assim, a escolha do m?todo de reconstru??o deve estar atrelada ? finalidade do estudo de PET/CT em quest?o, visto que um mesmo algoritmo de reconstru??o n?o se mostra adequado, em um ?nico equipamento, ?s avalia??es qualitativas e quantitativas, em diferentes ?mbitos. Conclui-se que a estrat?gia de harmoniza??o da quantifica??o do SUV apresentada neste trabalho mostrou-se eficaz na redu??o da variabilidade da quantifica??o de pequenas estruturas. Entretanto, para que a quantifica??o do SUV possa ser comparada entre diferentes equipamentos e institui??es, ? fundamental que, al?m da harmoniza??o da quantifica??o, seja mantida a padroniza??o da metodologia de preparo do paciente, visando minimizar a variabilidade atribu?da ao SUV decorrente de fatores biol?gicos.

Submitted by Setor de Tratamento da Informa??o - BC/PUCRS (tede2@pucrs.br) on 2015-06-19T11:53:50Z No. of bitstreams: 1 470623 - Texto Parcial.pdf: 1446399 bytes, checksum: 3695d8ae78a5226ff8ef00bf63332a89 (MD5) / Made available in DSpace on 2015-06-19T11:53:50Z (GMT). No. of bitstreams: 1 470623 - Texto Parcial.pdf: 1446399 bytes, checksum: 3695d8ae78a5226ff8ef00bf63332a89 (MD5) Previous issue date: 2015-03-06 / The gallium-68 (68Ga), an extremely promising positron-emitting radionuclide, has major advantages when compared to other radionuclides used in Positron Emission Tomography (PET), like fluor-18 and carbon-11. Differently from these PET radionuclides, gallium-68 is available from a 68Ge/68Ga generator, which allows its distribution even in nuclear medicine centers located far from cyclotrons. In recent years, an increase in the use of 68Ga PET radiopharmacy was observed around the world. However, in Brazil there is still only four centers with this technology available, mainly due to the difficulty in the access. Radiopharmaceuticals used for diagnostics are scarcely accessible in our country. Among radiopharmaceuticals most used around the world are the DOTA-peptides, somatostatin analogs for the diagnosis of neuroendocrine tumors. Considering the present scenario, this study aimed to develop a diagnostic kit of DOTA-TOC for labeling with 68Ga, with high radiolabeling yield and high radiochemical purity, thus stimulating the use of this innovative radionuclide in Brazil. / O G?lio-68 (68Ga), um radionucl?deo emissor de p?sitrons extremamente promissor, apresenta grandes vantagens quando comparado a outros radionucl?deos para uso em Tomografia por Emiss?o de P?sitrons (PET), como o fl?or-18 e carbono-11. Diferentemente destes radionucl?deos, que s?o produzidos em c?clotrons, o 68Ga ? produzido em gerador a partir de um radionucl?deo de longa vida ?til, o Germ?nio-68 (68Ge), o que permite sua distribui??o mesmo em centros de Medicina Nuclear que se localizem muito distantes de c?clotrons. Apesar de a radiofarm?cia com 68Ga ter se desenvolvido muito nos ?ltimos anos em todo o mundo, o Brasil ainda tem somente quatro centros que possuem essa tecnologia dispon?vel. Isto se deve especialmente ? dificuldade de utiliza??o, j? que os pept?deos necess?rios para a marca??o dos radiof?rmacos s?o importados. Dentre os radiof?rmacos que est?o sendo mais utilizados no mundo, destacam-se os DOTA-pept?deos, an?logos da somatostatina utilizados no diagn?stico de tumores de origem neuroend?crina. Diante do cen?rio atual, este trabalho teve por objetivo o desenvolvimento de um kit diagn?stico de DOTA-TOC para marca??o com 68Ga, com altos rendimento de marca??o e pureza radioqu?mica, e, assim, estimular a utiliza??o desse radionucl?deo inovador no Brasil.

Submitted by Setor de Tratamento da Informa??o - BC/PUCRS (tede2@pucrs.br) on 2016-12-01T15:49:46Z No. of bitstreams: 1 DIS_LUCAS_DIOVANI_LOPES_NARCISO_COMPLETO.pdf: 3232892 bytes, checksum: bde72a06ddadae90febae5d048b0471c (MD5) / Made available in DSpace on 2016-12-01T15:49:46Z (GMT). No. of bitstreams: 1 DIS_LUCAS_DIOVANI_LOPES_NARCISO_COMPLETO.pdf: 3232892 bytes, checksum: bde72a06ddadae90febae5d048b0471c (MD5) Previous issue date: 2016-08-31 / The activation of microglia is an important response to inflammatory processes in the central nervous system (CNS). There has been an increase in the number of researches in positron emission tomography (PET) using the radiotracer [11C]-(R)-PK11195, a selective ligand for TSPO, present at low levels in the healthy CNS. Although the literature brings many quantitative methods to analyze [11C]-(R)-PK11195 PET brain images, there is no standardized method of analysis applicable in clinical practice. Limitations involve the need for arterial blood sampling for the input function acquisition, aiming absolute quantification of kinetic parameters, such as the binding potential. When the arterial input function is not acquired, the use of models based on a reference region has quantification errors, since there is no brain region free of [11C]-(R)-PK11195 specific binding. The aim of this study is to investigate methods of quantitative and semiquantitative analysis of [11C]-(R)-PK11195 PET brain images, identifying limitations and capabilities. This work is inserted into a clinical study of patients with relapsing-remitting multiple sclerosis (MS) in treatment with fingolimod. There will be used [11C]-(R)-PK11195 PET brain images and structural T1-weighted magnetic resonance images. Methods of quantitative and semiquantitative analyzes will be compared, taking into consideration the specific aspects of MS. In the cross-sectional analysis, the use of SUVRWM in juxtacortical and periventricular regions presented the best results in differentiate between groups of patients with MS and the healthy control group. In the longitudinal analysis, the use of SUVRWM and SUVRCB may indicate the [11C]-(R)-PK11195 uptake behavior over time, and such measurements may be potential indicators of MS evolution when applied in the juxtacortical and periventricular regions. In conclusion, among the methods analyzed, SUVRWM method shows promising and satisfactory results, especially when applied to juxtacortical and periventricular regions. / A ativa??o da micr?glia ? uma resposta importante a processos inflamat?rios no sistema nervoso central (SNC). Estudos v?m utilizando a aquisi??o de imagens de tomografia por emiss?o de p?sitrons (PET) com o radiotra?ador [11C]-(R)-PK11195, ligante seletivo para TSPO, presente em n?veis baixos no SNC saud?vel. Embora a literatura traga diversos m?todos quantitativos de an?lise das imagens de PET cerebrais adquiridas com [11C]-(R)-PK11195, n?o existe m?todo padronizado de an?lise aplic?vel na pr?tica cl?nica. Limita??es envolvem a necessidade de amostragem de sangue arterial para aquisi??o da fun??o de entrada para quantifica??o verdadeira de par?metros cin?ticos, tais como o potencial de liga??o. Quando a fun??o de entrada arterial n?o ? adquirida, a utiliza??o de modelos baseados em regi?o de refer?ncia apresenta erros de quantifica??o, pois n?o existe uma regi?o no c?rebro que seja livre de liga??o espec?fica de [11C]-(R)-PK11195. O objetivo desse trabalho ? investigar m?todos de an?lise quantitativa e semiquantitativa de imagens de PET cerebrais adquiridas com [11C]-(R)-PK11195, identificando suas limita??es e potencialidades. Esse trabalho est? inserido dentro de um estudo cl?nico com pacientes com esclerose m?ltipla (EM) do tipo remitente-recorrente em tratamento com fingolimode. Ser?o utilizadas imagens cerebrais de PET adquiridas com [11C]-(R)-PK11195 e imagens estruturais de resson?ncia magn?tica ponderadas em T1. M?todos de an?lise quantitativa e semiquantitativa ser?o comparadas, levando em considera??o aspectos espec?ficos da EM. Na an?lise transversal, o uso do SUVRWM na regi?o justacortical e periventricular apresenta os melhores resultados de diferencia??o entre grupos de pacientes com EM e o grupo controle. Na an?lise longitudinal, o uso do SUVRWM e do SUVRCB podem indicar o comportamento da capta??o de [11C]-(R)-PK11195 ao longo do tempo, sendo tais medidas potenciais indicadores de evolu??o da EM quando aplicados nas regi?es justacortical e periventricular. Conclui-se que, dentre os m?todos analisados, o m?todo SUVRWM apresenta resultados promissores e satisfat?rios, em especial quando aplicado ?s regi?es justacortical e periventricular.

Submitted by Setor de Tratamento da Informa??o - BC/PUCRS (tede2@pucrs.br) on 2016-12-06T16:05:53Z No. of bitstreams: 1 DIS_JULIO_CESAR_MARTINI_COMPLETO.pdf: 2066306 bytes, checksum: ac62f8de7f443732c71f76471192afd6 (MD5) / Made available in DSpace on 2016-12-06T16:05:53Z (GMT). No. of bitstreams: 1 DIS_JULIO_CESAR_MARTINI_COMPLETO.pdf: 2066306 bytes, checksum: ac62f8de7f443732c71f76471192afd6 (MD5) Previous issue date: 2016-08-29 / Despite the activities administered to patients during Positron Emission Tomography (PET) scans are guided by methods and reference levels, in clinical practice there is a great discrepancy between these values. Current indications use dependent patient parameters (DPP), such as age and weight, without considering an assessment of the resulting image quality. The purpose of this study is to investigate how the anthropometric and physiological characteristics of patients influence the determination of 18F-FDG activity to be administered in PET/CT scans and image quality. Therefore, we conducted a preliminary study with three simulators of different diameters, representing patients with different sizes, with different values of activity concentration. Subsequently, we performed a retrospective study on a PET/CT image database acquired with 18F-FDG. Image quality indicators (NECR, and NECRN and SNRnorm) of the images of patients were determined for many PDP, namely: body weight, BMI, BSA, fat mass, mass-height ratio and equivalent diameter. The relationship between the administered activity, counts rates and the PDP, with image quality indicators were statistically evaluated. We concluded that the NECRN is the quality indicator which has the best correlation between the PDP, particularly with body mass and BMI. The image quality in can be estimated from the true coincidence events rate (TRUES) during PET/CT acquisition with 18F-FDG, due to the highly linear relationship with NECR for different body mass or BMI ranges, allowing the optimization of the administered activity based on the physical characteristics of the patient. / Apesar das atividades administradas a pacientes durante exames de Tomografia por Emiss?o de P?sitrons (PET) serem norteados por m?todos e n?veis de refer?ncia, na pr?tica cl?nica h? uma grande discrep?ncia entre esses valores. As indica??es atuais utilizam par?metros dependentes do paciente (PDP), como idade e peso, sem considerar uma avalia??o da qualidade da imagem obtida. A proposta deste trabalho ? investigar como as caracter?sticas antropom?tricas e fisiol?gicas dos pacientes influenciam na determina??o da atividade de 18F-FDG a ser administrada em exames de PET/CT e na qualidade das imagens. Para tanto, foi realizado um estudo preliminar com tr?s simuladores de diferentes di?metros, representando pacientes com tamanhos distintos, com valores distintos de concentra??o de atividade. Posteriormente, foi realizado um estudo retrospectivo em um banco de imagens de exames de PET/CT com 18F-FDG. Foram determinados indicadores de qualidade (NECR, NECRN e SNR) das imagens dos pacientes para diversos PDP, a saber: massa corporal, BMI, BSA, massa gorda, rela??o massa-altura e di?metro equivalente. Foram avaliadas estatisticamente as rela??es entre as atividades administradas, as taxas de contagens e os PDP, com os indicadores de qualidade da imagem. Conclui-se que a NECRN ? o indicador de qualidade que possui a melhor correla??o entre os PDP, particularmente com a massa corporal e o BMI. A qualidade da imagem pode ser estimada atrav?s da taxa de eventos de coincid?ncia verdadeira (TRUES) durante a aquisi??o das imagens de PET/CT com 18F-FDG, em virtude da rela??o altamente linear com o NECR para faixas distintas de massa corporal ou BMI, possibilitando a otimiza??o da atividade administrada em fun??o das caracter?sticas f?sicas do paciente.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-01-27T19:01:45Z No. of bitstreams: 1 MarcosPrettoMosmann_DISSERT.pdf: 1864596 bytes, checksum: 5469813ebb21427467b5a5e041958d8a (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-02-02T21:54:05Z (GMT) No. of bitstreams: 1 MarcosPrettoMosmann_DISSERT.pdf: 1864596 bytes, checksum: 5469813ebb21427467b5a5e041958d8a (MD5) / Made available in DSpace on 2016-02-02T21:54:05Z (GMT). No. of bitstreams: 1 MarcosPrettoMosmann_DISSERT.pdf: 1864596 bytes, checksum: 5469813ebb21427467b5a5e041958d8a (MD5) Previous issue date: 2014-02-26 / O c?ncer tem contribu?do drasticamente em termos de morbidade, mortalidade e custos para os sistemas de sa?de no mundo. O manejo desses pacientes ? complexo e novas tecnologias t?m emergido para o seu melhor cuidado. A tomografia por emiss?o de p?sitrons associada ? tomografia computadorizada (PET/CT) ? um m?todo diagn?stico dispon?vel mais recentemente no Brasil e determinou uma mudan?a de paradigma no fluxo do acompanhamento para muitos dos pacientes com c?ncer. Nesse sentido, o objetivo desse trabalho ? avaliar o acesso ao exame 18F-FDG PET/CT Oncol?gico no Estado do Rio Grande do Norte, segundo as caracter?sticas dos usu?rios, as indica??es e as fontes de financiamento do m?todo. Trata-se de um estudo individuado, observacional e transversal. Foram inclu?dos todos os pacientes que realizaram o exame 18F-FDG PET/CT com fins oncol?gicos na Liga Norteriograndense Contra o C?ncer no per?odo de 01/05/2011 a 30/04/2013. Coletaram-se dados relativos ? data de realiza??o do exame, sexo, idade, indica??o (diagn?stico / estadiamento / monitoriza??o da resposta ao tratamento / reestadiamento / suspeita de recidiva e controle), tipo de c?ncer ou condi??o que determinou a realiza??o do exame e a fonte de financiamento (p?blico ou particular). Nos dois anos que compreenderam o per?odo de coleta de dados do estudo, foram realizados 924 exames 18F-FDG PET/CT, em 718 pacientes. A m?dia de idade foi 51,4 (19,1) anos, variando entre 4 e 88 anos. Houve maior realiza??o do exame entre as mulheres, com um total de 539 exames (58,3%). Observou-se aumento da realiza??o do exame do primeiro ano (37,4%) para o segundo ano (62,6%). Quanto ?s indica??es do exame 18F-FDG PET/CT, foram realizados 3,8% com fins de diagn?stico, 6,6% para estadiamento, 1,0% para monitoriza??o da resposta ao tratamento, 49,8% para reestadiamento e 38,9% na suspeita de recidiva/controle, ou seja, apenas 10,4% dos exames foram realizados como estrat?gia inicial (diagn?stico e estadiamento). Em rela??o ao financiamento do 18F-FDG PET/CT, a maioria dos exames foi realizada com o conv?nio firmado com a Secretaria de Estado de Sa?de P?blica (45% dos exames). Os principais tipos de c?ncer encaminhados para o exame foram o linfoma (36,7%), c?ncer colorretal (10,6%), pulm?o (9,7%) e mama (8,5%). Foram realizados poucos exames PET/CT em alguns tipos de c?ncer, em especial es?fago (0,4%), p?ncreas (0,9%), est?mago (1,2%) e cabe?a e pesco?o (2,1%). De todos os exames em pacientes classificados como estrat?gia inicial, apenas 21% tiveram acesso ao exame pelo sistema p?blico, o que denota a pouca realiza??o do 18F-FDG PET/CT Oncol?gico no estado para esse fim. Para os sistemas de sa?de, ? fundamental promover o uso racional desse m?todo / Cancer has contributed dramatically in terms of morbidity, mortality and costs for healthcare systems in the world. The management of these patients is complex and new technologies have emerged for their best care. Positron emission tomography associated with computed tomography (PET/CT) is a diagnostic method available more recently in Brazil and led to a paradigm shift in the management for many cancer patients. Therefore, the aim of this study is to analyse the access to the exam 18F-FDG PET/CT in Oncology in the State of Rio Grande do Norte, according to the users characteristics, indications and sources of funding. This is an individual, observational and transversal study. All patients who underwent 18FFDG PET-CT examinations for oncologic purposes at Liga Norteriograndense contra o C?ncer from 01/05/2011 to 30/04/2013 were included. Data on the date of the examination, sex, age, indication (diagnosis / staging / monitoring response to treatment / restaging / suspected recurrence and control), type of cancer or condition that determined the exam and the source financing (public or private) were collected. During the two years that comprised the period of data collection for the study, 924 18F-FDG PET/CT exams were performed in 718 patients. The mean age was 51.4 (19.1) years, ranging from 4 to 88 years. There were more exams among women with a total of 539 examinations (58.3%). Increases were observed in the exams from the first year (37.4%) for the second year (62.6%). Accordingly, the 18F-FDG PET/CT indications were: 3.8% for diagnostic purposes, 6.6% for staging, 1.0% for monitoring response to treatment, 49.8% for restaging and 38.9% in suspected recurrence/control, only 10.4% of the exams were performed as initial strategy (diagnosis and staging). Regarding the financing of 18F-FDG PET/CT, the majority of tests were carried out with the agreement signed with the State Department of Public Health (45% of the exams). The main types of cancer referred for examination were lymphoma (36.7%), colorectal cancer (10.6%), lung (9.7%) and breast (8.5%). Few PET/CT studies were performed in some cancers, especially oesophagus (0.4%), pancreas (0.9%), stomach (1.2%) and head and neck (2.1%). Among those patients classified as initial strategy, only 21% had access to the exam by the public system, which demonstrates the low access of 18F-FDG PET/CT in Oncology in the state for this purpose. For health systems, it is essential to promote the rational use of this method.

Submitted by Caroline Xavier (caroline.xavier@pucrs.br) on 2017-06-23T15:05:11Z No. of bitstreams: 1 TES_EDUARDO_HERZ_BERDICHEVSKI_PARCIAL.pdf: 1111972 bytes, checksum: 207ba6b7db85b282db30b671c8ca89b8 (MD5) / Made available in DSpace on 2017-06-23T15:05:11Z (GMT). No. of bitstreams: 1 TES_EDUARDO_HERZ_BERDICHEVSKI_PARCIAL.pdf: 1111972 bytes, checksum: 207ba6b7db85b282db30b671c8ca89b8 (MD5) Previous issue date: 2017-01-20 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / It has been shown that the use of contrast media in PET/CT (positron emission tomography/ computed tomography) studies is beneficial when compared to an unenhanced CT scan. This is due to the fact that contrast media generates better contrast regarding adjacent structures, allows better characterization of abnormalities, and also allows visualizing alterations that do not present abnormal metabolic behavior. However, contrast agents generate more absorption of CT photons in relation to those of PET potentially giving rise to errors in attenuation correction of PET images. Errors converting the attenuation map from the CT to the PET scan may lead to inaccurate quantification of PET images. The occurrence of SUV (Standardized uptake value) modifications in lesions when PET images are corrected with either contrast-enhanced or unenhanced CT scans has already been studied. Our goal, however, was to study the occurrence of such alterations in relation with lesion size, and distance from the lesion to areas of high contrast concentration, such as high caliber vases and focal areas of the gastrointestinal tract (GIT). Methods: We obtained the SUVmax of 149 lesions, from 26 patients who underwent a PET/CT scan in which images were corrected using both an unenhanced computed tomography (PETCTUE) and a contrast-enhanced computed tomography (PETCTCE). In addition, we measured lesion sizes (smallest and largest diameter, and area) and their distance to large vessels and the GIT. Size measures were not taken when the lesion could not be visualized in the CT image. For lesions in which the distance to high contrast concentration areas was too large or too small, and could not be accurately estimated, the median distance of similar lesions was used to replace the measures. Following the repeated measures principle, we obtained Lin's concordance correlation coefficient and its confidence interval. A Bland-Altman analysis was performed using the absolute difference values and ratio, between PETCTCE and PETCTUE with concordance limits. Results: A total of 149 lesions could be visualized in PET. Eleven of them could not be identified in the CT, and so their measurements were not taken. For 16 lesions, the distance to high contrast concentration areas could not be obtained. The concordance level between the methods, by Lin's concordance correlation coefficient, was 0.99 (CCC: 0.99), and the confidence interval was 95% of 0.98 ? 0.99 (IC95%: 0.98 ? 0.99). The mean absolute difference between the methods was approximately zero and the relative difference was +3.37% (concordance limits of 95% between -2.72 and +2.72, and between -15.73 and +22.48%, respectively). Eighty-two lesions had their larger diameter below 17mm and the other 56 had a larger diameter above or equal to 17mm, with mean percent variation of SUVmax from PETCTCE to PECCTUE of 3.85% and 2.83%, respectively (p=0.54). Sixty-six lesions had a smaller diameter below 17mm and the remaining 72 had a smaller diameter equal to or above 17mm. The mean percent SUVmax variation from PETCTCE to PECCTUE was 2.71%?1,74 and 3.80% ?1,60, respectively (p=0.41). Eighty-two lesions had an area larger than 2.27 cm2 and the other 57 had an area equal to or larger than 2.27 cm2. The mean percent variation of the SUVmax obtained for PETCTCE and PETCTUE was 2.81%?1.64 e 3,83%?1.70, respectively (p=0.48). Sixty-seven lesions were more than 1.82 cm distant from large vessels/ GIT, and 82 were at a less than 1cm distance. The mean SUVmax variation between the methods (PETCTCE versus PETCTUE) was 0.57?1.65% e 4.98?1.61% respectively (p < 0.005). Conclusions: For the totality of studied lesions (149), as well as for the analysis regarding the factors size (non significant p) and distance (significant p), the medium SUVmax variation we identified it not clinically relevant. Thus, both contrast-enhanced and unenhanced PET/CT can be used for attenuation correction. / Nos estudos de PET/CT (tomografia por emiss?o de p?sitrons/ tomografia computadorizada), o uso de material contrastado endovenoso na CT mostra benef?cios diagn?sticos em rela??o a CT n?o contrastada. Isto ocorre pois o material contrastado al?m de gerar maior contraste entre as les?es em rela??o ?s estruturas adjacentes, e melhor caracterizar as anormalidades, tamb?m permite a visualiza??o de altera??es que n?o demonstram comportamento metab?lico anormal. Entretanto, os meios de contraste geram maior absor??o dos f?tons da CT em rela??o aos do PET, e isto tende a gerar erros na corre??o de atenua??o das imagens do PET. Esses erros na convers?o do mapa de atenua??o da CT para o do PET podem levar a inacur?cias na quantifica??o das imagens do PET. A ocorr?ncia de altera??es do SUV das les?es entre as imagens de PET corrigidas para atenua??o com o CT sem contraste e com o CT contrastado j? foi amplamente estudada. Nosso objetivo foi estudar essa ocorr?ncia em fun??o do tamanho das les?es e das dist?ncias entre elas e zonas de maior concentra??o de contraste, como ? o caso de vasos calibrosos e ?reas focais em trato gastrintestinal (TGI). M?todos: Mensuramos o SUVmax de 149 les?es em 26 pacientes cujos exames de PET/CT foram corrigidos tanto utilizando tomografia n?o-contrastada (PETCTSC) quanto tomografia contrastada (PETCTCC). Al?m disso, medimos as dimens?es das les?es (maior e menor di?metro e ?rea) e suas dist?ncias para vasos calibrosos e TGI. Medidas de tamanho n?o foram feitas quando n?o foram visualizadas na CT. Em les?es cujas dist?ncias de ?reas de maior contraste n?o puderam ser feitas com seguran?a por serem muito pr?ximas ou muito grandes, suas medidas foram repostas pela mediana de les?es similares quanto a este aspecto. Seguindo o princ?pio de medidas repetidas, obteve-se o n?vel de concord?ncia dos m?todos atrav?s do coeficiente de correla??o de concord?ncia de Lin e seu respectivo intervalo de confian?a. Realizou-se uma an?lise de Bland-Altman cruzando os valores de diferen?a absoluta e de raz?o entre o PETCTCC versus o PETCTSC com os limites de concord?ncia. Resultados: Das 149 les?es visualiz?veis no PET, 11 n?o demonstraram correspond?ncia na CT, n?o sendo mensuradas suas dimens?es. Dezesseis les?es n?o tiveram calculadas as suas dist?ncias para alguma ?rea de maior concentra??o de contraste e seus valores foram repostos. O n?vel de concord?ncia dos m?todos, pelo coeficiente de correla??o de concord?ncia de Lin, foi de 0.99 (CCC: 0.99) com intervalo de confian?a de 95% de 0.98 ? 0.99 (IC95%: 0.98 ? 0.99). A diferen?a m?dia absoluta entre os m?todos foi de aproximadamente zero e relativa de +3.37% (limites de concord?ncia de 95% entre -2.72 e +2.72 e entre -15.73 e +22.48% respectivamente). Oitenta e duas les?es apresentaram maior di?metro abaixo de 17mm e as outras 56, igual ou acima de 17mm, com diferen?a m?dia percentual dos SUVmax medida nos PETCTCC e PETCTSC igual a 3,85%?1,65 e 2,83%?1,80 respectivamente (p = 0,54). Sessenta e seis les?es apresentaram menor di?metro abaixo do que 17mm e as demais 72, di?metro igual ou acima de 17mm. A diferen?a m?dia percentual dos SUVmax medida nos PETCTCC e PETCTSC foi igual a 2,71%?1,74 e 3,80% ?1,60 respectivamente (p = 0,41). Oitenta e uma les?es apresentaram ?rea menor que 2,27 cm2 e as outras 57, ?rea igual ou maior que 2,27 cm2. A diferen?a m?dia percentual dos SUVmax medida nos PETCTCC e PETCTSC foi igual a 2,81%?1,64 e 3,83%?1,70 respectivamente (p = 0,48). Sessenta e sete les?es tinham dist?ncia de vasos calibrosos/ TGI acima de 1cm, e 82, igual ou menor que 1cm. A diferen?a m?dia percentual entre os m?todos (PETCTCC versus PETCTSC) foi igual a 0,57?1,65% e 4,98?1,61% respectivamente (p < 0,005). Conclus?es: Mesmo para o grupo total de les?es (149) bem como para os grupos de les?es separados em fun??o dos fatores ?tamanho? (p n?o significativo) e ?dist?ncia? (p significativo), a varia??o m?dia do SUVmax visualizada n?o tem relev?ncia cl?nica, tornando intercambi?vel a corre??o do PET pelo CT sem e com contraste.

Submitted by Caroline Xavier (caroline.xavier@pucrs.br) on 2017-06-30T13:52:23Z No. of bitstreams: 1 TES_LUCAS_PORCELLO_SCHILLING_PARCIAL.pdf: 7497659 bytes, checksum: 1ccccb228b48cbfe2cd307e26ad11ee2 (MD5) / Approved for entry into archive by Caroline Xavier (caroline.xavier@pucrs.br) on 2017-06-30T13:52:32Z (GMT) No. of bitstreams: 1 TES_LUCAS_PORCELLO_SCHILLING_PARCIAL.pdf: 7497659 bytes, checksum: 1ccccb228b48cbfe2cd307e26ad11ee2 (MD5) / Made available in DSpace on 2017-06-30T13:52:39Z (GMT). No. of bitstreams: 1 TES_LUCAS_PORCELLO_SCHILLING_PARCIAL.pdf: 7497659 bytes, checksum: 1ccccb228b48cbfe2cd307e26ad11ee2 (MD5) Previous issue date: 2016-12-16 / The pathophysiology of Alzheimer?s disease (AD) involves several pathological mechanisms, including amyloid-? and neurofibrillary tangles deposition, white matter changes and neurodegeneration. In this tranversal study, we investigated the interaction between white matter (WM) integrity and amyloid-? deposition as a potential determinant of cerebral hypometabolism in the Alzheimer?s disease (AD) continuum. Using the Alzheimer?s Disease Neuroimaging Initiative (ADNI) database, ninety-six subjects (cognitively normal (CN), n = 27; mild cognitive impairment (MCI), n = 49; and AD, n = 20) had positron emission tomography (PET) with [18F]Fluorodeoxyglucose ([18F]FDG) and [18F]Florbetapir, and magnetic resonance imaging (MRI) with Diffusion Tensor Imaging (DTI). In the first part of the study, we identified areas of fractional anisotropy (FA) reduction in angular bundle and fornix in the AD group. Among these regions, we selected for subsequent analyses a voxel of interest (VOI) in the angular bundle bilaterally. Then, using a voxel-based interaction model we examined the association of FA in the angular bundle, amyloid-? deposition, and also the potential interaction of these variables with [18F]FDG cerebral hypometabolism. In the AD group, [18F]FDG hypometabolism in the striatum, basal and mesial temporal, orbitofrontal, precuneus, anterior and posterior cingulate cortices was associated with the interaction between increase in [18F]Florbetapir standardized uptake value ratio (SUVR) in regions of interest and reduction in angular bundle FA. No significant clusters were identified in CN and MCI subjects. The interaction model, including amyloid-? deposition and WM disconnection, supports the concept of an integrative framework of AD pathophysiology where the combination of distinct pathological processes leads to progressive brain dysfunction in important cognitive-related areas / A fisiopatologia da Doen?a de Alzheimer (DA) envolve diversos mecanismos patol?gicos, como ac?mulo de ?-amiloide e de emaranhados neurofibrilares, altera??es na subst?ncia branca e neurodegenera??o. Este trabalho consiste em um estudo transversal, cujo objetivo foi investigar os efeitos da integridade da subst?ncia branca e do dep?sito de ?-amiloide como fatores determinantes do hipometabolismo cerebral no continuum da Doen?a de Alzheimer (DA). Utilizando dados obtidos atrav?s do cons?rcio internacional Alzheimer?s Disease Neuroimaging Initiative (ADNI), foram avaliados 96 indiv?duos (27 sujeitos cognitivamente normais - CN, 49 sujeitos com comprometimento cognitivo leve ? CCL, e 20 pacientes com DA) que realizaram um protocolo completo de neuroimagem com tomografia por emiss?o de p?sitrons (PET) com [18F]Fluordeoxiglicose ([18F]FDG) e [18F]Florbetapir e resson?ncia magn?tica nuclear (RMN) com a sequ?ncia de imagem de tensor de difus?o (DTI). Na primeira parte do estudo, no grupo DA foram identificadas ?reas de redu??o da anisotropia fracionada (FA) no fasc?culo angular e f?rnix. Dentre essas regi?es, um voxel de interesse (VOI) foi bilateralmente selecionado no fasc?culo angular para as an?lises subsequentes. Ap?s, examinamos a associa??o entre a FA no fasc?culo angular bilateral, o dep?sito de ?-amiloide atrav?s do PET [18F]Florbetapir Standardized Uptake Value Ratio (SUVR) nas regi?es de interesse e a poss?vel associa??o da intera??o entre ambos no hipometabolismo cerebral avaliado atrav?s de PET [18F]FDG. No grupo DA, a magnitude do hipometabolismo cerebral no corpo estriado, c?rtex orbito-frontal, temporal basal e mesial, pr?-c?neo e c?ngulo anterior e posterior foi determinada pelo efeito sin?rgico (intera??o) entre a densidade de agregados de ?-amiloide e o grau de desintegrac?o do fasc?culo angular, obtidos via [18F]Florbetapir e FA, respectivamente. N?o foram identificados clusters estatisticamente significativos nos grupos CN e CCL. Estes resultados ap?iam o conceito de que o efeito sin?rgico, mais do que os efeitos independentes da amiloidose e da desintegra??o da subst?ncia branca, determina o hipometabolismo regional na DA. De fato, o efeito da intera??o em nosso modelo, envolvendo o dep?sito de ?-amiloide e a desconex?o da subst?ncia branca, contribui para um conceito integrativo da fisiopatologia da DA, em que a a??o combinada de diferentes processos patol?gicos potencializa a degenerac?o do c?rebro.