Aplicação de técnicas de volumetria na avaliação da progressão de tumores cerebrais usando imagens de ressonância magnética

Este trabalho científico tem como principal finalidade o desenvolvimento de técnicas de volumetria capazes do fornecimento de informação para avalia-ção clínica de tumores primários do Sistema Nervoso Central (SNC), de grau IV – glioblastoma multiforme (GBM). Atualmente os métodos de avaliação da dimensão do tumor assentam em medições bidimensionais [1] [2]. No entanto, a avaliação clínica do tumor pode-rá ser mais completa quando realizada com base noutras características geomé-tricas, sejam a área, o perímetro, o volume e a posição do centro de massa. A ferramenta desenvolvida neste trabalho ao fornecer dados métricos e uma re-presentação volumétrica pré e pós-operatória do tumor, poderá contribuir para uma melhor avaliação da resposta à terapêutica instituída ao doente. As principais funções da ferramenta desenvolvida são descritas no capítu-lo Métodos. Estas estão relacionadas com o ajuste do nível de contraste da ima-gem original, com a binarização da mesma, com a definição da região da lesão tumoral (Region Of Interest - ROI) e com os cálculos efectuados sobre esta. São gerados dois tipos de resultados, dados métricos (área, volume e posição do centro de massa) e representações volumétricas (volume de tumor que capta contraste e volume de tumor que não capta contraste). Observou-se que nas imagens de exames onde o tumor apresenta regiões que captam pouco contraste é mais difícil e demorada a definição da ROI e por sua vez, a determinação do volume de tumor

Neutro-Connectedness Theory, Algorithms and Applications

Connectedness is an important topological property and has been widely studied in digital topology. However, three main challenges exist in applying connectedness to solve real world problems: (1) the definitions of connectedness based on the classic and fuzzy logic cannot model the “hidden factors” that could influence our decision-making; (2) these definitions are too general to be applied to solve complex problem; and (4) many measurements of connectedness are heavily dependent on the shape (spatial distribution of vertices) of the graph and violate the intuitive idea of connectedness. This research focused on solving these challenges by redesigning the connectedness theory, developing fast algorithms for connectedness computation, and applying the newly proposed theory and algorithms to solve challenges in real problems. The newly proposed Neutro-Connectedness (NC) generalizes the conventional definitions of connectedness and can model uncertainty and describe the part and the whole relationship. By applying the dynamic programming strategy, a fast algorithm was proposed to calculate NC for general dataset. It is not just calculating NC map, and the output NC forest can discover a dataset’s topological structure regarding connectedness. In the first application, interactive image segmentation, two approaches were proposed to solve the two most difficult challenges: user interaction-dependence and intense interaction. The first approach, named NC-Cut, models global topologic property among image regions and reduces the dependence of segmentation performance on the appearance models generated by user interactions. It is less sensitive to the initial region of interest (ROI) than four state-of-the-art ROI-based methods. The second approach, named EISeg, provides user with visual clues to guide the interacting process based on NC. It reduces user interaction greatly by guiding user to where interacting can produce the best segmentation results. In the second application, NC was utilized to solve the challenge of weak boundary problem in breast ultrasound image segmentation. The approach can model the indeterminacy resulted from weak boundaries better than fuzzy connectedness, and achieved more accurate and robust result on our dataset with 131 breast tumor cases

Development of wound healing biomaterials based on bacterial exopolysaccharides

Currently, biopolymers have aroused great interest mainly in the food, pharmaceutical, cosmetic, and also in the biomedical fields, due to the intelligent and versatile properties that present, namely, biocompatibility, biodegradability, and non-toxicity. In addition to these properties, many polymers have vital characteristics that assist in wound healing processes and, when incorporated into nanoparticles of elements such as silver (Ag), gold (Au), and selenium (Se), further increase the effectiveness of these polymers. Therefore, the main objective of this study was to determine the best conditions for the preparation of biocomposites for application in the treatment of wounds, using different extracellular bacterial polysaccharides (EPSs) (EPS1, EPS2, EPS3, EPS4, and FucoPol) as reducing and stabilizing agents for the synthesis of silver nanoparticles (AgNP), gold (AuNP) and selenium (SeNP). EPSs were characterized as to the composition in sugars and substituting groups, because, depending on the composition, they can interfere in some way in the properties of each one. EPS1 is composed mainly of mannose (56.1% mol), EPS2 and EPS3 are composed mainly of glucose, 67% mol and 39.1% mol, respectively, EPS4 is composed mainly of glucuronic acid (55.9% mol) and FucoPol by fucose (34.9 mol%). Biocomposites were also characterized by UV-vis spectroscopy, FTIR, TGA, XRD, DLS, Zeta potential and ICP. Cytotoxicity and wound healing effect of EPSs and EPS/NPs biocomposites were analyzed in human keratinocyte cells (HaCaT cell line). The samples were tested using a polymer concentration of 62.5 - 1000 mg/L and none of the samples showed cytotoxicity, except for the EPS3/Ag+ biocomposite when tested at a polymer concentration above 125 mg/L, with a content Ag+ above 6.9 mg/L (decreased cell viability by ~91.9%). On the other hand, among all EPSs and their functionalized materials, FucoPol and the biocomposite FucoPol/AgNP exhibited a greater capacity to promote keratinocyte migration in vitro. Although EPS1 did not present wound healing effect, the biocomposites EPS1/AgNP (100 mg/L) and EPS1/AuNP (500 mg/L) showed to promote the migration of HaCaT cells. The results obtained suggest that both FucoPol and the biocomposite FucoPol/AgNP, as well as the biocomposites EPS1/AgNP and EPS1/AuNP, may have potential application in dermo-cosmetics, mainly in wound healing mechanisms.Atualmente, os biopolímeros têm despertado grande interesse principalmente na área alimentar, farmacêutica, cosmética e também na área biomédica, devido às propriedades inteligentes e versáteis que apresentam, nomeadamente, biocompatibilidade, biodegradabilidade e não toxicidade. Além dessas propriedades, muitos polímeros possuem características vitais que ajudam em processos de cicatrização de feridas e quando incorporados com nanopartículas de elementos como a prata (Ag), ouro (Au) e selénio (Se), aumentam ainda mais a eficácia desses polímeros. Assim sendo, o principal objetivo deste estudo foi determinar as melhores condições de preparação de biocompósitos para aplicação em tratamento de feridas, utilizando diferentes polissacáridos bacterianos extracelulares (EPSs) (EPS1, EPS2, EPS3, EPS4 e FucoPol) como agentes redutores e estabilizadores para a síntese de nanopartículas de prata (AgNP), ouro (AuNP) e selénio (SeNP). Os EPSs foram caracterizados quanto à composição em açúcares e grupos substituintes, pois, dependendo da composição, podem interferir de certa forma nas propriedades apresentadas por cada um. O EPS1 é composto principalmente por manose (56.1 %mol), o EPS2 e o EPS3 são compostos principalmente por glucose, 67 %mol e 39.1 %mol respectivamente, o EPS4 é composto maioritariamente por ácido glucurónico (55.9 %mol) e o FucoPol por fucose (34.9 %mol). Os biocompósitos também foram caracterizados por espectroscopia UV-vis, FTIR, TGA, XRD, DLS, potencial Zeta e por ICP. A citotoxicidade e o efeito de cicatrização de feridas dos EPS e dos biocompósitos EPSs/NPs foram analisados em células de queratinócitos humanos (linha celular HaCaT). As amostras foram testadas usando uma concentração de polímero de 62.5-1000 mg/L e nenhuma amostra apresentou citotoxicidade, excepto para o biocompósito EPS3/Ag+ quando testado em uma concentração de polímero acima de 125 mg/L, com um teor de Ag+ acima de 6.9 mg/L (diminuição da viabilidade cellular em ~ 91.9%). Por outro lado, entre todos os EPSs e seus materiais funcionalizados, o FucoPol e o biocompósito FucoPol/AgNP exibiram uma maior capacidade de promover a migração in vitro dos queratinócitos. Embora o EPS1 não tenha apresentado efeito cicatrizante, os biocompósitos EPS1/AgNP (100 mg/L) e EPS1/AuNP (500 mg/L) mostraram promover a migração de células HaCaT. Os resultados obtidos sugerem que tanto o FucoPol e o biocompósito FucoPol/AgNP, bem como os biocompósitos EPS1/AgNP e EPS1/AuNP podem ter potencial aplicação na dermocosmética, sobretudo nos mecanismos de cicatrização de feridas

Multi-Dimensional Tumor Detection in Automated Whole Breast Ultrasound Using Topographic Watershed

Automated whole breast ultrasound (ABUS) is becoming a popular screening modality for whole breast examination. Compared to conventional handheld ultrasound, ABUS achieves operator-independent and is feasible for mass screening. However, reviewing hundreds of slices in an ABUS image volume is time-consuming. A computer-aided detection (CADe) system based on watershed transform was proposed in this study to accelerate the reviewing. The watershed transform was applied to gather similar tissues around local minima to be homogeneous regions. The likelihoods of being tumors of the regions were estimated using the quantitative morphology, intensity, and texture features in the 2-D/3-D false positive reduction (FPR). The collected database comprised 68 benign and 65 malignant tumors. As a result, the proposed system achieved sensitivities of 100% (133/133), 90% (121/133), and 80% (107/133) with FPs/pass of 9.44, 5.42, and 3.33, respectively. The figure of merit of the combination of three feature sets is 0.46 which is significantly better than that of other feature sets (p-value < 0.005). In summary, the proposed CADe system based on the multi-dimensional FPR using the integrated feature set is promising in detecting tumors in ABUS images