Repositório RCAAP

INTRODUCTION: Cardiology has been one of the most important areas of medicine. For several applications to diagnose the heart functions diseases the measurement of left ventricular (LV) cavity area and LV fractional area change are of vital necessity. To achieve this task, it is necessary to trace the border of left ventricle, which manual tracing is a tedious and time-consuming work. To solve this problem, many techniques to automate this border detection have been developed using the specialist tracing as gold standard. METHODS: The purpose of this approach is to analyze the features of the main techniques applied to left ventricle border detection in medical imaging. To facilitate understanding, the left ventricle border detection techniques are divided into three categories: image-based techniques, model-based techniques and pixel-based techniques. For each of the category, a literature review was made to get examples of the techniques applied to left ventricle border detection and to describe them. The result of this review is a comparative tablewhere the main features of each technique is compared. CONCLUSION: From the comparative table we can conclude that the not mentioning of many features of the techniques by the authors and the lack of a standardization of the evaluation techniques hamper a more satisfactory comparison.

INTRODUCTION: The detection of the somatosensory response (SR) is an important tool for the neurophysiological evaluation in the intra and post-operative period of some vascular and spine surgeries. Particularly, the SR identification with a maximum false positive ratio by means of Objective Response Detection (ORD) techniques could lead to a less subjective procedure. In this work a novel ORD, the Rice Detector (RD), is presented and its theoretical critical value is obtained. METHODS: The probability of detection (PD) of RD is assessed for different numbers of eletroencephalographic (EEG) signal epochs (M = 30, 60, 120, 240) and signal-to-noise ratios (-20 to 10 dB, in steps of 1 dB) by means of simulation. The simulated PD curves (PDc) are compared with the theoretical ones and with the PDc of the Magnitude-Squared Coherence (MSC), a well-known ORD technique. The performance of RD and MSC are also compared for real EEG data. The comparison is based on the DP for estimates calculated with M = 30, 60, 120 and 240 epochs. RESULTS: The results showed that the simulated PDc follow the theoretical ones and both the MSC and RD present similar performance, with slight advantage for this latter at low M-values. However, for real data, no statistical significant difference (proportion test with alpha=0.05) was found between MSC and RD. CONCLUSION: Both techniques presented mean detection rates varying from 70% to 90%, even for intermediate M-value (120 epochs), and can be useful for evoked response detection applications.

INTRODUCAO Procedimentos cirúrgicos ortopdicos como a osteotomia, em que se realiza o corte da tíbia, são muito comuns e devem ser muito bem executados para que sejam obtidos bons resultados. Nesse cenário, o estudo de como o osso reage ao processo de corte um tópico relevante de estudos. O objetivo deste trabalho apresentar um modelo matemático do processo de corte na tíbia humana por uma serra automática, usando o mtodo de Bond Graph. MTODOS: Com base em um trabalho anterior, foi desenvolvido um modelo para a força de reação ao corte da serra. Alm disso, foi desenvolvido um modelo embasado no mtodo Bond Graph para se determinar a resposta das diversas partes do osso à ação da serra. Foram tambm realizadas análises no domínio da frequência para se analisar a estabilidade do sistema. RESULTADOS: Foram obtidos e apresentados os resultados das simulações descritas. Os resultados mostraram boa concordância com o comportamento esperado para a força de reação à serra e para a resposta do material ósseo ao corte. Alm disso, as análises no domínio da frequência mostraram que o mtodo de modelagem proposto tem características promissoras com relação a estabilidade do sistema. CONCLUSÃO: Os resultados sugerem que o mtodo tem bom potencial para ser usado, no futuro próximo, para análises do processo de perfuração antes de procedimentos cirúrgicos. Entretanto, estudos adicionais sobre a estabilidade e sobre o projeto adequado de um controlador de velocidade são ainda necessários.

INTRODUCTION: The aim of this work is to present a physical implementation of a noninvasive methodology to analyze the directional sensitivity of human auditory system. A computer controlled experiment set-up has been designed and developed to study the behavior of human subjects under the presentation of interaural time delays and interaural amplitude differences for several sensation levels. METHODS: The proposed methodology comprises: the application of trains of low-pass filtered narrow pulses as acoustic binaural stimuli; the automatic, simultaneous and random variation of interaural time delays and interaural amplitude differences; the absence of human interference along the experimental sessions, except for the decision of the listener under test; the minimization of adaptation effects. RESULTS: Numerous lateralization judgments have been accomplished in order to investigate the transduction mechanism which allows deciding which side of subjects medial plane the source of binaural acoustic stimuli is located in. The behavior of decision time with the order of judgment, the sensation levels and the interaural differences in time and amplitudes has been analyzed. CONCLUSION: The noninvasive, reliable and automatic approach here presented allows obtaining psychophysical responses associated to the neuro-physiological phenomena underneath lateralization capability.

INTRODUÇÃO: Entre os riscos intrínsecos na assistência à saúde, a infusão de medicamentos é uma preocupação constante. Essa pesquisa analisou os tipos de notificações de eventos adversos, com a possibilidade dos profissionais envolvidos no uso incorreto de operação de Bombas de Infusão (BI). Os autores realizaram uma pesquisa dos problemas decorrentes de eventos adversos gerados da utilização de BI e desenvolveram um instrumento de identificação de conhecimentos de habilidades e usabilidades de BI. MÉTODOS: A metodologia utilizada no estudo foi desenvolvida em quatro fases. Na primeira e segunda fase, realizou-se uma pesquisa no banco de dados de relatos sobre notificações na unidade de Tecnovigilância da Agência Nacional de Vigilância Sanitária (ANVISA) com o levantamento de dados, classificação de equipamentos, tipificação de problemas e análise de causas comuns. Na terceira fase realizou-se a análise do banco de dados de notificações de um fabricante de BI. Na última fase foi feita a análise de causas comuns para desenvolver as ações preventivas e o desenvolvimento do instrumento proposto. RESULTADOS: Foram analisados os anos de 2006 a 2011 onde existiam 1.971 relatos sobre notificações de equipamentos médicos hospitalares, sendo 251 desses relatos sobre BI (12,6%). Essa porcentagem foi a maior encontrada entre todos os equipamentos notificados. CONCLUSÃO: O estudo permitiu afirmar que os profissionais que operam as BI, muitas vezes possuem carência de conhecimento e/ou falta de compromisso com a atividade. Pode-se afirmar que um aspecto importante e inquestionável sobre o uso de BI é a relação com a segurança.

INTRODUÇÃO: Dentre as doenças que afetam a população mundial, destaca-se a preocupação com a Doença Pulmonar Obstrutiva Crônica (DPOC), que, segundo a Organização Mundial de Saúde, pode se constituir na terceira causa de morte mais importante em todo mundo no ano de 2030. Visando contribuir com o auxílio ao diagnóstico médico, esta pesquisa centraliza seus esforços na etapa de segmentação dos pulmões, visto que esta é a etapa básica de sistema de Visão Computacional na area de pneumologia. MÉTODOS: Este trabalho propõe um novo método de segmentação dos pulmões em imagens de Tomografia Computadorizada (TC) do tórax chamado de Método de Contorno Ativo (MCA) Crisp Adaptativo 2D. Este MCA consiste em traçar automaticamente uma curva inicial dentro dos pulmões, que se deforma por iterações sucessivas, minimizando energias que atuam sobre a mesma, deslocando-a até as bordas do objeto. O MCA proposto é o resultado do aperfeiçoamento do MCA Crisp desenvolvido previamente, visando aumentar a sua exatidão, diminuindo o tempo de análise e reduzindo a subjetividade na segmentação e análise dos pulmões dessas imagens pelos médicos especialistas. Este método por iterações sucessivas de minimização de sua energia, segmenta de forma automática os pulmões em imagens de TC do tórax. RESULTADOS: Para sua validação, o MCA Crisp Adaptativo é comparado com os MCAs THRMulti, THRMod, GVF, VFC, Crisp e também com o sistema SISDEP, sendo esta avaliação realizada utilizando como referência 24 imagens, sendo 12 de pacientes com DPOC e 12 de voluntários sadios, segmentadas manualmente por um pneumologista. Os resultados obtidos demonstram que o método proposto é superior aos demais. CONCLUSÃO: Diante dos resultados obtidos, pode-se concluir que este método pode integrar sistemas de auxílio ao diagnóstico médico na área de Pneumologia.

INTRODUCTION: Breast cancer has the second highest world's incidence rate, according to the Brazilian National Cancer Institute (INCa). Clinical examination and mammography are the best methods for early diagnosis. Computer-aided detection (CADe) and computer-aided diagnosis (CADx) systems are developed to improve mammographic diagnosis. Basically, CADx systems have three components: (i) segmentation, (ii) parameters extraction and selection, (iii) lesion classification. The first step for a CADx system is segmentation. METHODS: A microcalcification segmentation method is proposed, based on morphological operators, Otsu's Method and radiologists' knowledge. Pre-processing with top-hat operators improves contrast and reduces background noise. The Otsu's method automatically selects the best grey-level threshold to segment microcalcifications, obtaining binary images. Following, inferior reconstruction and morphological dilatation operators are applied to reconstruct lost structure details and fill small flaws in the segmented microcalcifications. Finally, the Canny edge detection is applied to identify microcalcifications contour candidates for each region-of-interest (ROI). Two experienced radiologists intervene in this semi-automatic method, firstly, selecting the ROI and, then, analyzing the segmentation result. The method was assessed in 1000 ROIs from 158 digital images (300 dpi, 8 bits). RESULTS: Considering the radiologists opinion, the rates of ROIs adequately segmented to establish a diagnosis hypothesis were 97.8% for one radiologist and 97.3% for the other. Using the Area Overlap Measure (AOM) and the 2136 microcalcifications delineated by an experienced radiologist as gold standards, the method achieved an average AOM of 0.64±0.14, being 0.56±0.09 for small microcalcifications and 0.66±0.13 for the large ones. Moreover, AOM was 0.64±0.13 for the benign and 0.64±0.14 for the malignant lesions with no statistical differences between them. CONCLUSION: Based on these findings, the proposed method could be used to develop a CADx system that could help early breast cancer detection.

INTRODUÇÃO: Grande parte da população mundial é afetada por doenças pulmonares, como é o caso das broncopatias constituídas pela asma, bronquiectasia e a bronquite. O diagnóstico de broncopatias é baseado no estado das vias aéreas. Neste sentido, a segmentação automática das vias aéreas em imagens de Tomografia Computadorizada (TC) do tórax é uma etapa fundamental para auxílio ao diagnóstico dessas doenças. MÉTODOS: O presente trabalho avalia algoritmos e desenvolve métodos de segmentação automática das vias aéreas 2D. Tais métodos são compostos por algoritmos de detecção de vias aéreas, sendo estes rede neural Multilayer Perceptron (MLP) e Análise de Densidades Pulmonares (ADP), e por algoritmos de segmentação de vias aéreas, sendo estes Crescimento de Região (CR), Método de Contornos Ativos (MCA) Balão e Topológico Adaptativo. RESULTADOS: Os resultados foram obtidos em três etapas: análise comparativa entre os algoritmos de detecção MLP e ADP, com um padrão-ouro adquirido por três médicos com expertise em imagens de TC do tórax; análise comparativa entre algoritmos de segmentação MCA balão, MCA topológico adaptativo, MLP e CR; e avaliação das possíveis combinações entre os algoritmos de detecção e segmentação, resultando no método completo para segmentação automática das vias aéreas em 2D. CONCLUSÃO: A baixa incidência de falso-negativo e a redução significativa de falso-positivo, resulta em coeficiente de similaridade e sensibilidade superior a 91% e 87% respectivamente, para uma combinação dos algoritmos, com qualidade de segmentação satisfatória.

INTRODUÇÃO: O diabetes mellitus é uma condição sistêmica que pode causar retardo da resposta tecidual frente a uma lesão. Diversos estudos têm apontado o laser como importante ferramenta terapêutica para o auxílio do processo de reparo tecidual. Contudo, poucos estudos foram realizados com o emprego de LED (Light Emitting Diode). Assim, o objetivo deste trabalho foi analisar o efeito da terapia com LED (λ = 945 ± 20nm) de baixa intensidade sobre tecido epitelial de ratos diabéticos em processo de reparo. MÉTODOS: Para tal, foi realizada a indução de diabetes experimental em 20 ratos machos (Wistar), com administração de 40mg/kg, por via endovenosa, de mono-hidrato de aloxana diluído em solução tampão. Após 14 dias, os animais foram submetidos à incisão tecidual na região dorsal, seguida de sutura e divididos em grupo-controle (GI e GIII, 3 e 7 dias pós-lesão, respectivamente), e grupo-tratado com LED (GII e GIV, 3 e 7 dias pós-lesão, respectivamente). Os animais do grupo tratado (n = 10) foram irradiados de forma transcutânea, em duas sessões (30 minutos e 48 horas pós-lesão). RESULTADOS: O número de fibroblastos foi significativamente maior no GIV em relação ao GIII. CONCLUSÃO: Considerando o aumento do número de fibroblastos (análise quantitativa) e o adequado fechamento da lesão (análise qualitativa), pode-se concluir que houve um efeito positivo da terapia LED na região do infravermelho próximo sobre o processo de reparo, após 7 dias de lesão tecidual em animais diabéticos (GIV).

INTRODUÇÃO: O grande número de deficientes auditivos faz da perda auditiva um sério problema social, econômico e de saúde pública. Próteses auditivas e implantes cocleares representam os principais dispositivos utilizados como paliativos por pessoas com deficiência auditiva, sendo que os implantes cocleares são muitas vezes a única opção nos casos de deficiência auditiva severa e profunda. Nesse artigo discute-se de maneira geral os diferentes aspectos envolvendo implantes cocleares, tanto de âmbito tecnológico como seu papel socioeconômico. MÉTODOS: Baseado em dados do SUS, IBGE e outras fontes, um levantamento qualitativo e quantitativo é feito pela primeira vez especificamente para a população brasileira. O artigo discute ainda o estado da arte das tecnologias envolvidas no implante coclear, com base em literatura científica e informações de fabricantes, bem como as perspectivas para as próximas gerações de implantes cocleares. CONCLUSÃO: Há potencial e demanda para evoluções nos implantes atuais. A implantação precoce é benéfica para pacientes e sociedade, compensando os custos econômica e socialmente. No entanto, as políticas públicas de reabilitação necessitam se adequar para atender com eficácia à crescente população afetada pela deficiência auditiva.

INTRODUÇÃO: O e-learning surgiu como uma forma complementar de ensino, trazendo consigo vantagens como o aumento da acessibilidade da informação, aprendizado personalizado, democratização do ensino e facilidade de atualização, distribuição e padronização do conteúdo. Neste sentido, o presente trabalho tem como objeto apresentar uma ferramenta, intitulada de ISE-SPL, cujo propósito é a geração automática de sistemas de e-learning para a educação médica, utilizando para isso sistemas ISE (Interactive Spaced-Education) e conceitos de Linhas de Produto de Software. MÉTODOS: A ferramenta consiste em uma metodologia inovadora para a educação médica que visa auxiliar o docente da área de saúde na sua prática pedagógica por meio do uso de tecnologias educacionais, todas baseadas na computação aplicada à saúde (Informática em Saúde). RESULTADOS: Os testes realizados para validar a ISE-SPL foram divididos em duas etapas: a primeira foi feita através da utilização de um software de análise de ferramentas semelhantes ao ISE-SPL, chamado S.P.L.O.T; e a segunda foi realizada através da aplicação de questionários de usabilidade aos docentes da área da saúde que utilizaram o ISE-SPL. CONCLUSÃO: Ambos os testes demonstraram resultados positivos, permitindo comprovar a eficiência e a utilidade da ferramenta de geração de softwares de e-learning para o docente da área da saúde.

INTRODUCTION: Ultrasound Transit-Time flowmeters are based on the fact that the time required for an ultrasound pulse to propagate through a given distance in a moving medium is a function of the vectorial sum of pulse propagation velocity and medium velocity. The most common application of this flowmeter in medicine is in the evaluation of blood flow in arteries and veins during heart vascular surgery. The present article describes the design, construction and evaluation of a flow phantom for transit-time flowmeters calibration. METHODS: Basically, it is a hydraulic circuit containing degassed and distilled water. In such a circuit, a constant differential water level is established between two columns that are interconnected by tubes with defined resistance, which determines a known flow rate. A basic theoretical model to estimate the system Reynolds Number and resistance was developed. RESULTS: A flow range between 4.43 ± 0.18 ml.min-1 and 106.88 ± 0.27 ml.min-1 was found to be compatible with physiological values in small vessels. The pressure range was between 0.20 ± 0.03 cmH2O and 12.53 ± 0.07 cmH2O, and the larger Reynolds Number was 1134.07. Experimental and theoretical resistance values were similar. CONCLUSION: A reproducible phantom was designed and built to be assembled with standard low-cost materials and is capable of generating adjustable and continuous flows that can be used to calibrate TTFM systems.

INTRODUCTION: Skin health and skin care to reduce the effects of aging are the main interests of many researchers. The skin is very important because it protects the body from various effects of the external environment, and studies of the largest organ of the human body have been conducted since antiquity. In skin, aging effects are severe enough to promote changes in cell structure and biochemical composition. In this study, we quantitatively analyzed the water content and natural moisturizing factor of human facial skin in vivo and in real time by confocal Raman spectroscopy. This non-invasive technique is capable of providing detailed information on the biochemical composition at different depth profiles in the skin. METHODS: We studied 10 volunteers, phototype II (40 and 50 years old), using a confocal Raman system to examine the skin surface down to 25 µm. Raman spectra were obtained before product use (T0), and after 30 days of continuous use of cosmetics (T30). RESULTS: The results show a significant increase of 6.4% in water content in the surface layer of the facial skin after the cosmetic use. The amounts of natural moisturizing factor (NMF) compounds were also increased. Urocanic acid underwent a greater change in relation to carboxylic acid pyrrolidone, with a 38.5% increase in the stratum corneum. CONCLUSION: Confocal Raman spectroscopy identified changes in the biochemical composition of the superficial layers of the epidermis, which suggests the anti-aging efficacy of the formulation.

INTRODUCTION: Function induction problems are frequently represented by affinity measures between the elements of the inductive sample set, and kernel matrices are a well-known example of affinity measures. METHODS: The objective of the present work is to obtain information about the relations between data from a calculated kernel matrix by initially assuming that those geometric relations are consistent with known labels. To assess the relation between the data structure and the labels, a classifier based on kernel density estimation (KDE) was used. The performance of the selected width using the method presented in this paper was compared to the performance of a method described in the literature; the literature method was based on minimizing error minimization and balancing bias and variance. The main case study, which was to predict the response to neoadjuvant chemotherapy treatment, consists of evaluating whether a set of training data from genomic expression data from breast tumors and the genomic expression from the tumor of one patient can be used to determine whether there will be a pathological complete response. RESULTS: For the tested databases, the proposed method showed statistically equivalent results with the literature method; however, in some cases, the proposed method had a better overall performance when considering both large and small classes. CONCLUSION: The results demonstrate the feasibility of selecting models by directly calculating densities and the geometry from the class separation.

INTRODUCTION: Increased production and disorders in the circulation or absorption of cerebrospinal fluid (CSF) leads to increased intracranial pressure and causes a condition called hydrocephalus. The most common treatment for this disorder is the implantation of a ventricle-peritoneal shunt, which consists of the insertion of a ventricular catheter in the cerebral ventricle, a neurological valve for drainage control and a peritoneal catheter that leads the CSF to the abdominal region. The International Organization for Standardization (ISO) 7197 introduced requirements for the design and production of the shunts and neurological valve, including in vitro hydrodynamic tests, which are indispensable for evaluating the performance of the CSF drainage systems. METHODS: A testing rig built in accordance with ISO 7197 was evaluated for the uncertainty of flow and opening and closing pressure measurements, the pressure-flow relationship and reflux neurological valve resistance. The infusion pump and pressure measurement system were evaluated for calibration, hysteresis behavior and stability to determine the experimental uncertainties from hydrodynamic testing of two commercial products. RESULTS: The equipment showed uncertainties of less than 1% in the infusion pump, less than 4% in the pressure sensor and adequate performance for the hydrodynamic tests. CONCLUSION: The hydrodynamic test rig allowed the opening and closing pressures and the resistance to reflux to be obtained, and it also allowed the determination of the pressure and flow rate characteristics of two neurological commercial valves with experimental uncertainties that do not impact the results and the evaluation of in vitro performance of a shunt.

INTRODUCTION: Breast cancer is the second most common type of cancer in the world, being more common among women and representing 22% of all new cancer cases every year. The sooner it is diagnosed, the better the chances of a successful treatment are. Mammography is one way to detect non-palpable tumors that cause breast cancer. However, it is known that the sensitivity of this exam can vary considerably due to factors such as the specialist's experience, the patient's age and the quality of the images obtained in the exam. The use of computational techniques involving artificial intelligence and image processing has contributed more and more to support the specialists in obtaining a more precise diagnosis. METHODS: This paper proposes a methodology that exclusively uses texture analysis to describe features of masses in digitized mammograms. To increase the efficiency of texture feature extraction, the diversity index's capability to detect patterns of species co-occurrence is used. For this purpose, the Gleason and Menhinick indexes are used. Finally, the extracted texture is classified using the Support Vector Machine, looking to differentiate the malignant masses from the benign. RESULTS: The best result was obtained using the Gleason index, with 86.66% accuracy, 90% sensitivity, 83.33% specificity and an area under the ROC Curve (Az) of 0.86. CONCLUSION: Both indexes showed statistically similar performance; however, the Gleason index was slightly superior.

INTRODUCTION: Patients with diabetes mellitus exhibit a delay in the lesion repair process. The active components of Cenostigma macrophyllum may represent a viable alternative to facilitate the recovery of these lesions. The aim of this study was to evaluate the effects of emulsion oil-water Cenostigma macrophyllum in the repair process of lesions in rats with induced diabetes. METHODS: 63 male rats (Wistar, 200-250 g body weight, 30-40 days old) were distributed into the following groups: control (C), diabetic (D) and diabetic treated with Cenostigma macrophyllum (P), subdivided based on the experimental times, days 7, 14 and 28, with 21 animals per main group. Diabetes mellitus (DM) was induced by administration of streptozotocin (50 mg/kg via penile vein and 12-h fasting) and confirmed at day 21 (glycemic index &gt; 240 mg/dL). In the animals of group P, 0.5 ml of the oil-water emulsion obtained from the plant seed was used. The samples were removed and hemisectioned, and one portion was used for the quantitative histological analysis of collagen using Masson's trichrome staining, while another portion was analyzed by FT-Raman spectroscopy. RESULTS: A higher percentage area of the volume of collagen fibers was observed for the experimental time Day 14 in group P compared with group D (p < 0.001). Regarding the ratio of areas of the amides I (1700‑1600 cm-1) and III (1245-1345 cm-1), the groups D and P show the opposite behavior. CONCLUSION: Cenostigma macrophyllum accelerated the repair process in skin of diabetic ratsfor14 days.

INTRODUCTION: Rheumatic diseases are considered public health problems affecting millions of people worldwide resulting in high and rising health-care costs. In this work, Fourier Transform Infrared spectroscopy associated to Partial Least Square regression (PLS) analysis was used to diagnose rheumatoid arthritis (RA) from human serum. METHODS: The sera of 94 individuals were collected, which included 47 from rheumatic patients and 47 from healthy individuals. The results from PLS analysis were compared to standard clinical trials such as anti-citrullinated peptide antibodies, C- Reactive protein, and Rheumatoid factor. RESULTS: For clinical diagnosis, the anti-citrullinated peptide antibodies of second generation proved to be the most specific to diagnosis rheumatoid arthritis even after long periods of drug therapy. CONCLUSIONS: The qualitative PLS analysis has shown higher values of IgM of RA group, but the difference was very small. The RA patients were under medication, which interfered with the IgM concentration.

INTRODUCTION: Decision-making on medical equipment management is a daily task for clinical engineers, but it may prove difficult to easily extract relevant information from the large amount of data from computerized maintenance management systems. This article describes a simple method of medical equipment classification based on corrective maintenance indicators. METHODS: Three indicators were calculated based on the number of events, duration and cost of corrective maintenance. Three classes were defined according to the indicator values of different equipment ages: class A for 0-4 years, class B for 5-9 years, and class C for equipment older than 10 years. The method was applied to 2,134 pieces of equipment from the Health Service system of the University of Campinas. RESULTS: From the total, 51.7% of the equipment were classified as C, 4.2% as B and 44.1% as A. The infusion pump for general use was the type of equipment of which most units were in the C class (84.7%), even though almost 50% of them were acquired within less than 9 years, and would thus be expected to be classified as A and B. Among the pumps in class C, 39.5% were from a single manufacturer, although the equipments were acquired recently. CONCLUSION: The developed classification may be an important tool for raising alerts about equipment more prone to maintenance problems, as well as for identification of equipments with acceptable maintenance history, supporting decision-making on equipment replacement.

INTRODUCTION: Areas of the brain that are associated with the vestibular system can be activated using galvanic vestibular stimulation. These areas can be studied through a combination of galvanic vestibular stimulation with functional magnetic resonance imaging (fMRI). In order to provide an appropriate sequence of galvanic stimulation synchronous with the MRI pulse sequence, a specific electronic device that was built and assessed is presented. METHODS: The electronic project of the GVS is divided in analog and digital circuits. The analog circuits are mounted in an aluminum case, supplied by sealed batteries, and goes inside the MRI room near to the feet of the subject. The digital circuits are placed in the MRI control room. Those circuits communicate through each other by an optical fiber. Tests to verify the GVS-MRI compatibility were conducted. Silicone (in-house) and Ag/AgCl (commercial) electrodes were evaluated for maximum balance and minimal pain sensations. fMRI experiments were conducted in eight human volunteers. RESULTS: GVS-MRI compatibility experiments demonstrate that the GVS did not interfere with the MRI scanner functionality and vice versa. The circular silicone electrode was considered the most suitable to apply the galvanic vestibular stimulation. The 1 Hz stimulation sinusoid frequency produced the biggest balance and the less pain sensations when compared to 2 Hz. The GVS was capable of eliciting activation in the precentral and postcentral gyri, in the central sulcus, in the supplementary motor area, in the middle and inferior frontal gyri, in the inferior parietal lobule, in the insula, in the superior temporal gyrus, in the middle cingulate cortex, and in the cerebellum. CONCLUSION: This study shows the development and description of a neurovestibular stimulator that can be safely used inside the MRI scanner room without interfering on its operation and vice versa. The developed GVS could successfully activate the major areas involved with multimodal functions of the vestibular system, demonstrating its validity as a stimulator for neurovestibular research. To the best of our knowledge, this is the first work that shows the development and the construction of a galvanic vestibular stimulator that could be safely used inside the MRI room.