RESUMO
BACKGROUND: Stent placement has been widely used to assist coiling in cerebral aneurysm treatments. The present study aimed to investigate the hemodynamic effects of stenting on wide-necked intracranial aneurysms. METHODS: Three idealized plexiglass aneurismal models with different geometries before and after stenting were created, and their three-dimensional computational models were constructed. Flow dynamics in stented and unstented aneurismal models were studied using in vitro flow visualization and computational fluid dynamics (CFD) simulations. In addition, effects of stenting on flow dynamics in a patient-specific aneurysm model were also analyzed by CFD. RESULTS: The results of flow visualization were consistent with those obtained with CFD simulations. Stent deployment reduced vortex inside the aneurysm and its impact on the aneurysm sac, and decreased wall shear stress on the sac. Different aneurysm geometries dictated fundamentally different hemodynamic patterns and outcomes of stenting. CONCLUSIONS: Stenting across the neck of aneurysms improves local blood flow profiles. This may facilitate thrombus formation in aneurysms and decrease the chance of recanalization.
Assuntos
Embolização Terapêutica/métodos , Aneurisma Intracraniano/terapia , Stents , Humanos , HidrodinâmicaRESUMO
An automatic inspection system for biochip's print quality is presented in this paper. It consists of an automatic mechanical control, a CCD sensor for getting the image of PET boart, and the special computer software for image processing and recognition. Experimental results indicate that this system is capable of providing a precise and effective realtime inspection for biochips' print quality.
Assuntos
Técnicas Biossensoriais/instrumentação , Processamento de Imagem Assistida por Computador/métodos , Procedimentos Analíticos em Microchip/métodos , Reconhecimento Automatizado de Padrão/métodos , Software , Técnicas Biossensoriais/métodos , Desenho de Equipamento , Controle de QualidadeRESUMO
The numerical simulation of the conventional 1-way bypass graft and the presented 2-way bypass graft used in the stenosed femoral arteries were completed. Purpose of the present study was to ascertain whether the modified geometry configuration of 2-way bypass graft could improve the flow conditions of femoral bypass graft. The physiological flows in 1-way and 2-way models were simulated with finite element method under the same calculation conditions. Comparisons were made between the hemodynamics of 1-way and 2-way models. The results suggested that 2-way bypass graft could result in more favorable and regular flow conditions than 1-way bypass graft, and could decrease the probability of intimal hyperplasia, restenosis and surgery failure in femoral bypass graft.
Assuntos
Anastomose Cirúrgica/métodos , Prótese Vascular , Artéria Femoral/fisiopatologia , Artéria Femoral/cirurgia , Modelos Cardiovasculares , Cirurgia Assistida por Computador/métodos , Animais , Velocidade do Fluxo Sanguíneo , Simulação por Computador , Constrição Patológica/fisiopatologia , Constrição Patológica/cirurgia , Humanos , Análise Numérica Assistida por Computador , Resistência ao CisalhamentoRESUMO
AIM: To propose a simple and effective method suitable for analyzing the angle and distribution of 2-dimensional collagen fiber in larger sample of small intestine and to investigate the relationship between the angles of collagen fiber and the pressure it undergoes. METHODS: A kind of 2-dimensional visible quantitative analyzing technique was described. Digital image-processing method was utilized to determine the angle of collagen fiber in parenchyma according to the changes of area analyzed and further to investigate quantitatively the distribution of collagen fiber. A series of intestinal slice's images preprocessed by polarized light were obtained with electron microscope, and they were processed to unify each pixel. The approximate angles between collagen fibers were obtained via analyzing the images and their corresponding polarized light. The relationship between the angles of collagen fiber and the pressure it undergoes were statistically summarized. RESULTS: The angle of collagen fiber in intestinal tissue was obtained with the quantitative analyzing method of calculating the ratio of different pixels. For the same slice, with polarized light angle's variation, the corresponding ratio of different pixels was also changed; for slices under different pressures, the biggest ratio of collagen fiber area was changed either. CONCLUSION: This study suggests that the application of stress on the intestinal tissue will change the angle and content of collagen fiber. The method of calculating ratios of different pixel values to estimate collagen fiber angle was practical and reliable. The quantitative analysis used in the present study allows a larger area of soft tissue to be analyzed with relatively low cost and simple equipment.
