Accessibility / Report Error
Revista Brasileira de Engenharia Biomédica, Volume: 30, Issue: 3, Published: 2014
  • Computational neuroscience in perspective

    Almeida, Antônio-Carlos Guimarães de; Rodrigues, Antônio Márcio; Infantosi, Antonio Fernando Catelli
  • Lung disease detection using feature extraction and extreme learning machine

    Ramalho, Geraldo Luis Bezerra; Rebouças Filho, Pedro Pedrosa; Medeiros, Fátima Nelsizeuma Sombra de; Cortez, Paulo César

    Abstract in English:

    INTRODUCTION: The World Health Organization estimates that by 2030 the Chronic Obstructive Pulmonary Disease (COPD) will be the third leading cause of death worldwide. Computerized Tomography (CT) images of lungs comprise a number of structures that are relevant for pulmonary disease diagnosis and analysis. METHODS: In this paper, we employ the Adaptive Crisp Active Contour Models (ACACM) for lung structure segmentation. And we propose a novel method for lung disease detection based on feature extraction of ACACM segmented images within the cooccurrence statistics framework. The spatial interdependence matrix (SIM) synthesizes the structural information of lung image structures in terms of three attributes. Finally, we perform a classification experiment on this set of attributes to discriminate two types of lung diseases and health lungs. We evaluate the discrimination ability of the proposed lung image descriptors using an extreme learning machine neural network (ELMNN) comprising 4-10 neurons in the hidden layer and 3 neurons in the output layer to map each pulmonary condition. This network was trained and validated by applying a holdout procedure. RESULTS: The experimental results achieved 96% accuracy demonstrating the effectiveness of the proposed method on identifying normal lungs and diseases as COPD and fibrosis. CONCLUSION: Our results lead to conclude that the method is suitable to integrate clinical decision support systems for pulmonary screening and diagnosis.
  • Effectiveness of ozonated water in the reprocessing of blood dialyzers

    Canada, Morian Lauana Miguelão; Abelan, Ursulandrea Sanches; Zangaro, Renato Amaro; Kozusny-Andreani, Dora Inês; Yamazaki, Roseli de Fátima Custódio

    Abstract in English:

    INTRODUCTION: Ozone is a potent antibacterial agent. Because ozone oxidizes organic material, it directly attacks microorganisms resulting in safe, fast and economical sterilization at low temperatures. This study evaluated the efficacy of ozonated water in the reprocessing of dialyzers obtained from a hemodialysis service in São José do Rio Preto. METHODS: A total of 23 blood dialyzers were collected at the conclusion of the morning hemodialysis shift. The equipment was collected after the maximum number of reuses, with the last disinfection performed with purified water (obtained by reverse osmosis and subsequent reverse ultrafiltration). The number and species of microorganisms in the dialyzers were evaluated before and after treatment with ozonated water. The ozonation of sterile deionized water was achieved by direct contact between the water and the ozone generating equipment. RESULTS:The mean number of microorganisms before sterilization was 1,47.10(9) colony forming units per ml (CFU/ml). After treatment with ozonated water, the number of microorganisms was 4,80.10¹ CFU/ml. CONCLUSION: Ozonated water is an effective decontaminant for most blood dialyzers.
  • Assessment of walker-assisted gait based on Principal Component Analysis and wireless inertial sensors

    Martins, Maria; Elias, Arlindo; Cifuentes, Carlos; Alfonso, Manuel; Frizera, Anselmo; Santos, Cristina; Ceres, Ramón

    Abstract in English:

    INTRODUCTION:This study investigates a gait research protocol to assess the impact of a walker model with forearm supports on the kinematic parameters of the lower limb during locomotion. METHODS: Thirteen healthy participants without any history of gait dysfunction were enrolled in the experimental procedure. Spatiotemporal and kinematic gait parameters were calculated by using wireless inertial sensors and analyzed with Principal Component Analysis (PCA). The PCA method was selected to achieve dimension reduction and evaluate the main effects in gait performance during walker-assisted gait. Additionally, the interaction among the variables included in each Principal Component (PCs) derived from PCA is exposed to expand the understanding of the main differences between walker-assisted and unassisted gait conditions. RESULTS:The results of the statistical analysis identified four PCs that retained 65% of the data variability. These components were associated with spatiotemporal information, knee joint, hip joint and ankle joint motion, respectively. CONCLUSION: Assisted gait by a walker model with forearm supports was characterized by slower gait, shorter steps, larger double support phase and lower body vertical acceleration when compared with normal, unassisted walking.
  • Digital controller design considering hardware constraints: application in a paraplegic patient

    Sanches, Marcelo Augusto Assunção; Gaino, Ruberlei; Kozan, Renan Fernandes; Teixeira, Marcelo Carvalho Minhoto; Carvalho, Aparecido Augusto de; Covacic, Márcio Roberto; Alves, Carlos Antonio; Urban, Mateus Fernandes Réu; Junqueira, Marcos Vinícius Nascimento; Cardim, Rodrigo; Assunção, Edvaldo; Gentilho Junior, Edno

    Abstract in English:

    INTRODUCTION: A methodology was developed for implementing closed-loop control algorithms and for evaluating the behavior of a system, considering certain component restrictions used in laboratory implementation. METHODS: Mathematical functions representing a model of the biological system were used for knee extension/flexion movements. A Proportional Integral Derivative (PID) controller and another one using the root locus method were designed to control a patient’s leg position by applying functional electrical stimulation (FES). The controllers were simulated in Matlab and ISIS Proteus. After the simulations were performed, the codes were embedded in a microcontroller, and tests were conducted on a paraplegic volunteer. To the best of the authors’ knowledge, this is the first time that ISIS Proteus software resources have been used prior to implementing a closed-loop system designed to control the leg position of patients. RESULTS:This method obviates the application of initial controller tests directly to patients. The response obtained in the experiment with a paraplegic patient complied with the specifications set in terms of the steady-state error, the settling time, and the percentage overshoot. The proposed procedure was successfully applied for the implementation of a controller used to control the leg position of a paraplegic person by electrical muscle stimulation. CONCLUSION:The methodology presented in this manuscript can contribute to the implementation of analog and digital controllers because hardware limitations are typically not taken into account in the design of controllers.
  • Evaluation of nuclear magnetic resonance spectroscopy variability

    Barreto, Felipe Rodrigues; Otaduy, Maria Concepción García; Salmon, Carlos Ernesto Garrido

    Abstract in English:

    INTRODUCTION: The intrinsically high sensitivity of Magnetic Resonance Spectroscopy (MRS) causes considerable variability in metabolite quantification. In this study, we evaluated the variability of MRS in two research centers using the same model of magnetic resonance image scanner. METHODS: Two metabolic phantoms were created to simulate magnetic resonance spectra from in vivo hippocampus. The phantoms were filled with the same basic solution containing the following metabolites: N-acetyl-aspartate, creatine, choline, glutamate, glutamine and inositol. Spectra were acquired over 15 months on 26 acquisition dates, resulting in a total of 130 spectra per center. RESULTS: The phantoms did not undergo any physical changes during the 15-month period. Temporal analysis from both centers showed mean metabolic variations of 3.7% in acquisitions on the same day and of 8.7% over the 15-month period. CONCLUSION: The low deviations demonstrated here, combined with the high specificity of Magnetic Resonance Spectroscopy, confirm that it is feasible to use this technique in multicenter studies in neuroscience research.
  • Three-dimensional analysis of an orthodontic delta spring

    Rodrigues, Fábio Rodrigo Mandello; Borges, Paulo César; Luersen, Marco Antônio; Ferreira, Marcelo do Amaral

    Abstract in English:

    INTRODUCTION: The purpose of this study was to analyze the force system, moment-force ratios (M/F) and von Mises stresses in an orthodontic delta spring using a 3D finite element model. The M/F ratio produced by an orthodontic spring is related to the different types of tooth movement that are likely to occur in the sagittal and occlusal planes. METHODS: Analyses were performed using a 3D finite element model, and a data acquisition system was used to validate the numerical results. RESULTS: Reactive forces between 0.0 and 2.0 N were observed along the x-axis, while null values were observed along the y- and z-axes. The maximum activation that ensured geometric stability and mechanical stresses below the elastic limit of the material was 10.0 mm. CONCLUSION: The results indicate that a delta spring can provide (i) uncontrolled tipping for activation of less than 1.0 mm; (ii) controlled counterclockwise tipping for activation between 1.0 and 4.5 mm; (iii) translation for activation between 4.5 and 5.0 mm; and (iv) controlled clockwise tipping in the sagittal plane for activation between 5.0 and 10.0 mm. No tooth movement was observed in the occlusal plane for the M/F ratios observed.
  • Corrosion and microstructural characterization of martensitic stainless steels submitted to industrial thermal processes for use in surgical tools

    Marcuci, José Renato Jatobá; Souza, Elki Cristina de; Camilo, Claudia Cristiane; Di Lorenzo, Pedro Luiz; Rollo, João Manuel Domingos de Almeida

    Abstract in English:

    INTRODUCTION: The mechanical properties and corrosion resistance of a material are dependent on its microstructure and can be modified by phase transformation. When a phase transformation occurs in a material it usually forms at least one new phase, with physical-chemical characteristics that differ from the original phase. Moreover, most phase transformations do not occur instantly. This paper presents an evaluation of the phase transformation of martensitic stainless steels ASTM 420A and ASTM 440C when submitted to different thermal processes. METHODS: Dilatometry tests were performed with several continuous heating and cooling rates in order to obtain the profiles of the continuous heating transformation (CHT) and continuous cooling transformation (CCT) diagrams for these two types of steel. Also, the temperature ranges for the formation of the different phases (ferrite and carbides; ferrite; austenite and carbides; non-homogeneous and homogeneous austenite phases) were identified. Rockwell hardness (HRC) tests were performed on all thermally treated steels. Anodic and cathodic potential dynamic polarization measurements were carried out through immersion in enzymatic detergent as an electrolyte for different samples submitted to the thermal processes in order to select the best routes for the heat treatment and to recommend steels for the manufacture of surgical tools. RESULTS: The martensitic transformation temperature tends to increase with increasing temperature for the initiation of cooling. The 440C steel had a higher hardness value than the 420A steel at the austenitizing temperature of 1100 °C. Above the austenitizing temperature of 1100 °C, the material does not form martensite at the cooling rate used, which explains the sharp decline in the hardness values. CONCLUSION: The study reported herein achieved its proposed objectives, successfully investigating the issues and indicating solutions to the industrial problems addressed, which are frequently encountered in the manufacture of surgical instruments.
  • Manufacture of custom-made cranial implants from DICOM® images using 3D printing, CAD/CAM technology and incremental sheet forming

    Castelan, Jovani; Schaeffer, Lirio; Daleffe, Anderson; Fritzen, Daniel; Salvaro, Vanessa; Silva, Fábio Pinto da

    Abstract in English:

    INTRODUCTION: This work aims to pre-operatively manufacture custom-made low-cost implants and physical models (‘biomodels’) of fractured skulls. The pre-DOI: operative manufacturing of biomodels and implants allows physicians to study and plan surgery with a greater possibility of achieving the expected result. Customization contributes to both the esthetic and functional outcome of the implant because it considers the anatomy of each patient, while the low cost allows a greater number of people to potentially benefit. METHODS: From CT images of a fractured skull, a CAD model of the skull (biomodel) and a restorative implant were constructed digitally. The biomodel was then physically constructed with 3D Printing, and Incremental Sheet Forming (ISF) was used to manufacture the implant from a sheet of pure grade 2 titanium. Before cutting the implant’s final shape from a pre-formed sheet, heat treatment was performed to avoid deformations caused by residual stresses generated during the ISF process. RESULTS: A comparison of the dimensions of the implant and its respective CAD biomodel revealed geometric discrepancies that can affect both functional and aesthetic efficiency. Nevertheless, the final shape preserved symmetry between the right and left sides of the skull. Electron microscopy analysis did not indicate the presence of elements other than pure titanium. CONCLUSION: Dimensional variability can be decreased with changes in the manufacturing process (i.e., forming and cutting) and the heating ramp. Despite biomedical characteristics, there was no contamination of the implant by harmful chemical elements. 3D Printing was effective in making the biomodel, enabling pre-operative planning and improving physician-patient communication. Current results indicate that ISF is a process that can be used to obtain custom-made implants.
  • Is it possible to identify the gender and age group of adults from gait analysis with hip-knee cyclograms?

    Abreu, Ródney Silva; Naves, Eduardo Lázaro Martins; Caparelli, Thiago Bruno; Mariano, Daniel Teodoro Gonçalves; Dionísio, Valdeci Carlos

    Abstract in English:

    INTRODUCTION: Cyclograms are gait analysis tools that characterize the geometric aspect of the pattern of locomotion. Cyclograms are angle-angle diagrams that are very useful for representing cyclic patterns such as walking. This study is based on the hypothesis that parameters extracted from hip-knee cyclograms of individuals walking on a treadmill with 0° and 5° slopes can be used to determine the age group and sex of the volunteers. METHODS: In total, 40 physically active healthy adult volunteers, 20 young people (10 of each gender) and 20 elderly (10 of each gender), were divided into 4 groups, and the average value of area (A), perimeter (P) and the ratio P/√A of cyclogram were calculated, as well as the speed and cadence. RESULTS: The young male (YM) speeds were higher than the elderly male (EM) speeds (p=0.00), and the young female (YF) speeds were higher than the elderly female (EF) speeds (p=0.00). No difference in speed was found between YM and YF (p=0.59) or between EM and EF (p=0.95). The parameters extracted directly from the cyclogram allowed us to distinguish the studied groups according to age group (p<0.05), especially with the treadmill inclined at 5°, but it was not enough to determine gender (p>0.51). CONCLUSION: The hypothesis was partially confirmed because parameters extracted from the hip-knee cyclograms could differentiate volunteers by age group but not gender.
  • A mass-spring model of the auditory system in otosclerosis

    Fragoso, Lygia Bueno; Magalhães, Max de Castro; Las Casas, Estevam Barbosa de; Santos, Juliana Nunes; Rabelo, Alessandra Terra Vasconcelos; Oliveira, Rafaella Cristina

    Abstract in English:

    INTRODUCTION: This paper aims to describe a model to simulate otosclerosis using a mass-spring model and to correlate the results with the clinical and audiological data on the disease. METHODS: A mass-spring model was used to represent the behavior of the auditory system simulating otosclerosis. The model consisted of six masses (air volume in the external auditory canal; tympanic membrane; malleus; incus; stapes, and cochlear fluid), springs and dashpots simulating the supporting ligaments and muscles. The parameters to simulate the disease were obtained from the literature; stapedial annular ligament stiffness was increased by 10-fold and to 100-fold and stapes mass increased by 5-fold. RESULTS: There was a decrease in stapes displacement in the lower frequencies when the stiffness of the stapedial annular ligament was increased. It was also found a reduction in stapes displacement in the higher frequencies with increased stapes mass. CONCLUSION:The increased stiffness of the stapedial annular ligament can be an indication of early stage disease, whereas increased bone growth suggests disease progression. The results of the simulation are in agreement with the clinical and audiological disease and support the need for further study of the stapedial annular ligament to find ways to evaluate its functioning and thus enable early detection of hearing losses caused by changes in that structure.
SBEB - Sociedade Brasileira de Engenharia Biomédica Sociedade Brasileira de Engenharia Biomédica, Centro de Tecnologia, , bloco H, sala 327 - Cidade Universitária, 21941-914 Rio de Janeiro - RJ , Tel./Fax.:: (55 21) 2562-8591 - Rio de Janeiro - RJ - Brazil
E-mail: rbeb@rbeb.org.br