No description available.

Magnetic Resonance Imaging (MRI) was used to determine changes in the size of the Inferior Vena Cava (IVC) as a result of blood pooling induced by lower body negative pressure (LBNP). Images of the IVC of supine human subjects (10 males, 10 females) were obtained under four conditions: 1) steady-state 0 mmHg LBNP, 2) steady-state –35 mmHg LBNP, 3) ramping from 0 to –35 mmHg LBNP, 4) ramping from –35 to 0 mmHg LBNP. Volumes for a given IVC segment were obtained under the first two conditions during both end inspiration and end expiration breath-holds. Inferior Vena Cava widths were measured under all four conditions at the levels of portal entry and portal exit. The IVC volume for men and women combined decreased 41% due to LBNP (p andlt; 1.02 x 10-9). The IVC was 64.4% wider at portal exit than at portal entry in men (p andlt; 0.0003). Lower Body Negative Pressure induced a decrease in men's vena cava width up to 46% at portal exit and up to 62% at portal entry. Supported by NASA EPSCoR WKU 522611 and NIH GCRC MO1 RR262.

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Brain lesions are regions of abnormal or damaged tissue in the brain, commonly due to stroke, cancer or other disease. They are diagnosed primarily using neuroimaging, the most common modalities being Magnetic Resonance Imaging (MRI) or Computed Tomography (CT). Brain lesions have a high degree of variability in terms of location, size, intensity and form, which makes diagnosis challenging. Traditionally, radiologists diagnose lesions by inspecting neuroimages directly by eye; however, this is time-consuming and subjective. For these reasons, many automated methods have been developed for lesion delineation (segmentation), lesion identification and diagnosis. The goal of this thesis is to improve and develop automated methods for delineating brain lesions from multimodal MRI scans. First, we propose an improvement to existing segmentation methods by exploiting the bilateral quasi-symmetry of healthy brains, which breaks down when lesions are present. We augment our data using nonlinear registration of a neuroimage to a reflected version of itself, leading to an improvement in Dice coefficient of 13 percent. Second, we model lesion volume in brain image patches with a modified Poisson regression method. The model accurately identified the lesion image with the larger lesion volume for 86 percent of paired sample patches. Both of these projects were published in the proceedings of the BIOSTEC 2020 conference. In the last two chapters, we propose a confidence-based approach to measure segmentation uncertainty, and apply an unsupervised segmentation method based on mutual information.

A Síndrome da Dor Femoropatelar (SDFP) é uma das disfunções mais freqüentes do joelho, que acomete adultos jovens do sexo feminino. Embora os fatores etiológicos da SDFP ainda não estejam bem estabelecidos, autores apontam as alterações da cinemática patelar como o principal fator causal. A intervenção conservadora é freqüentemente indicada para o tratamento destes indivíduos, abrangendo exercícios em cadeia cinética aberta (CCA) e cadeia cinética fechada (CCF). O objetivo deste trabalho foi analisar a cinemática patelar durante o repouso e exercícios em indivíduos saudáveis e com SDFP. Participaram deste trabalho, 20 voluntários clinicamente saudáveis e 19 com SDFP submetidos a exames de ressonância nuclear magnética (RNM) durante o repouso, contração isométrica voluntária máxima (CIVM) em CCA e CCF com o joelho posicionado a 15º, 30º e 45º de flexão. As imagens de RNM foram avaliadas pelo programa e-film medical na obtenção dos ângulos do sulco (AS), ângulo de congruência (AC), ângulo de tilt patelar (ATP), ângulo patelar lateral (APL), deslocamento lateral patelar (DLP) e o bisect offset (BO). O coeficiente de correlação intraclasse (ICC) foi aplicado para verificar a confiabilidade intra-examinador e o modelo linear de efeitos mistos aplicado para as comparações inter e intra-grupo, sendo estabelecido nível de significância de 5%. Os resultados do ICC revelaram níveis excelentes de confiabilidade (ICC> 0,75) para todas as medidas de ambos os grupos. De acordo com os dados analisados, pode-se constatar que o grupo SDFP apresenta um maior deslocamento lateral da patela durante o repouso, CIVM em CCA e CCF com o joelho posicionado a 15º de flexão em relação ao grupo controle. Na comparação entre os posicionamentos do joelho e entre as cadeias, para ambos os grupos verificou-se um melhor equilíbrio patelar com o joelho fletido a 30º e a 45º com a CIVM em CCA e CCF. Com o joelho posicionado a 15º de flexão, a patela apresenta-se em sua posição de maior instabilidade, mesmo durante a CIVM em CCF e CCA para ambos os grupos. Desta maneira pode-se concluir que exercícios em CCA e CCF com o joelho posicionado a 30º e a 45º apresentam uma melhor estabilidade patelar em relação aos exercícios com o joelho posicionado a 15º de flexão. / Patellofemoral Pain Syndrome (PPS) is one of the most common knee dysfunctions affecting young adult women. Although PFPS etiologic factors remain uncertain, authors have reported that changes in patellar kinematics as the main cause. Conservative interventions are frequently indicated, which includes open kinetic chain (OKC) and closed kinetic chain (CKC) exercises. This study had the objective to analyze patellar kinematics on individuals with PFPS and health controls, at rest position and while performing exercises. Thirty-nine volunteers participated in this study (20 healthy individuals and 19 with PFPS) and were subjected to nuclear magnetic resonance (NMR) at the following conditions: at rest, maximal voluntary isometric contraction (MVIC) in OKC and CKC with the knee flexed at 15º, 30º, and 45º. NMR images were evaluated using e-film medical for the following angles: sulcus angle (SA), congruence angle (CA), patellar tilt angle (PTA), lateral patellar angle (LPA), lateral displacement of the patella (LDP), and bisect offset (BO). The interclass coefficient correlation (ICC) was applied to verify intra-rater reliability and the linear mixed effects model for inter- and intra-group comparisons, with level of significance at 5%. ICC results revealed excellent reliability levels (ICC> 0.75) for all measurements in both groups. The analyzed data reveal that, compared to the control group, the PFPS group presents greater lateral displacement of the patella at rest, MVIC in OKC and CKC with the knee flexed at 15º. Comparisons among knee positions and kinetic chains, in both groups, it was observed that better patellar balance was obtained with the knee flexed at 30º and 45º with MVIC in OKC and CKC. For both groups, the position with most instability of the patella is with the knee flexed at 15º, even during MVIC in CKC and OKC. Hence, it is concluded that OKC and CKC exercises with the knee flexed at 30º and 45º promote better stability of the patella with regards to exercises performed with the knee flexed at 15º

A Síndrome da Dor Femoropatelar (SDFP) é uma das disfunções mais freqüentes do joelho, que acomete adultos jovens do sexo feminino. Embora os fatores etiológicos da SDFP ainda não estejam bem estabelecidos, autores apontam as alterações da cinemática patelar como o principal fator causal. A intervenção conservadora é freqüentemente indicada para o tratamento destes indivíduos, abrangendo exercícios em cadeia cinética aberta (CCA) e cadeia cinética fechada (CCF). O objetivo deste trabalho foi analisar a cinemática patelar durante o repouso e exercícios em indivíduos saudáveis e com SDFP. Participaram deste trabalho, 20 voluntários clinicamente saudáveis e 19 com SDFP submetidos a exames de ressonância nuclear magnética (RNM) durante o repouso, contração isométrica voluntária máxima (CIVM) em CCA e CCF com o joelho posicionado a 15º, 30º e 45º de flexão. As imagens de RNM foram avaliadas pelo programa e-film medical na obtenção dos ângulos do sulco (AS), ângulo de congruência (AC), ângulo de tilt patelar (ATP), ângulo patelar lateral (APL), deslocamento lateral patelar (DLP) e o bisect offset (BO). O coeficiente de correlação intraclasse (ICC) foi aplicado para verificar a confiabilidade intra-examinador e o modelo linear de efeitos mistos aplicado para as comparações inter e intra-grupo, sendo estabelecido nível de significância de 5%. Os resultados do ICC revelaram níveis excelentes de confiabilidade (ICC> 0,75) para todas as medidas de ambos os grupos. De acordo com os dados analisados, pode-se constatar que o grupo SDFP apresenta um maior deslocamento lateral da patela durante o repouso, CIVM em CCA e CCF com o joelho posicionado a 15º de flexão em relação ao grupo controle. Na comparação entre os posicionamentos do joelho e entre as cadeias, para ambos os grupos verificou-se um melhor equilíbrio patelar com o joelho fletido a 30º e a 45º com a CIVM em CCA e CCF. Com o joelho posicionado a 15º de flexão, a patela apresenta-se em sua posição de maior instabilidade, mesmo durante a CIVM em CCF e CCA para ambos os grupos. Desta maneira pode-se concluir que exercícios em CCA e CCF com o joelho posicionado a 30º e a 45º apresentam uma melhor estabilidade patelar em relação aos exercícios com o joelho posicionado a 15º de flexão. / Patellofemoral Pain Syndrome (PPS) is one of the most common knee dysfunctions affecting young adult women. Although PFPS etiologic factors remain uncertain, authors have reported that changes in patellar kinematics as the main cause. Conservative interventions are frequently indicated, which includes open kinetic chain (OKC) and closed kinetic chain (CKC) exercises. This study had the objective to analyze patellar kinematics on individuals with PFPS and health controls, at rest position and while performing exercises. Thirty-nine volunteers participated in this study (20 healthy individuals and 19 with PFPS) and were subjected to nuclear magnetic resonance (NMR) at the following conditions: at rest, maximal voluntary isometric contraction (MVIC) in OKC and CKC with the knee flexed at 15º, 30º, and 45º. NMR images were evaluated using e-film medical for the following angles: sulcus angle (SA), congruence angle (CA), patellar tilt angle (PTA), lateral patellar angle (LPA), lateral displacement of the patella (LDP), and bisect offset (BO). The interclass coefficient correlation (ICC) was applied to verify intra-rater reliability and the linear mixed effects model for inter- and intra-group comparisons, with level of significance at 5%. ICC results revealed excellent reliability levels (ICC> 0.75) for all measurements in both groups. The analyzed data reveal that, compared to the control group, the PFPS group presents greater lateral displacement of the patella at rest, MVIC in OKC and CKC with the knee flexed at 15º. Comparisons among knee positions and kinetic chains, in both groups, it was observed that better patellar balance was obtained with the knee flexed at 30º and 45º with MVIC in OKC and CKC. For both groups, the position with most instability of the patella is with the knee flexed at 15º, even during MVIC in CKC and OKC. Hence, it is concluded that OKC and CKC exercises with the knee flexed at 30º and 45º promote better stability of the patella with regards to exercises performed with the knee flexed at 15º

京都大学 / 0048 / 新制・論文博士 / 博士(医学) / 乙第13133号 / 論医博第2137号 / 新制||医||1024(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 溝脇 尚志, 教授 妹尾 浩, 教授 鈴木 実 / 学位規則第4条第2項該当 / Doctor of Medical Science / Kyoto University / DFAM

Image guidance using in-beam real-time magnetic resonance (MR) imaging is expected to improve the targeting accuracy of proton therapy for moving tumors, by reducing treatment margins, detecting interfractional and intrafractional anatomical changes and enabling beam gating. The aim of this study is to quantitatively characterize the static magnetic field and image quality of a 0.22T open MR scanner that has been integrated with a static proton research beamline. The magnetic field and image quality studies are performed using high-precision magnetometry and standardized diagnostic image quality assessment protocols, respectively. The magnetic field homogeneity was found to be typical of the scanner used (98ppm). Operation of the beamline magnets changed the central resonance frequency and magnetic field homogeneity by a maximum of 16Hz and 3ppm, respectively. It was shown that the in-beam MR scanner features sufficient image quality and influences of simultaneous irradiation on the images are restricted to a small sequence-dependent image translation (0.1–0.7mm) and a minor reduction in signal-to-noise ratio (1.3%–5.6%). Nevertheless, specific measures have to be taken to minimize these effects in order to achieve accurate and reproducible imaging which is required for a future clinical application of MR integrated proton therapy.