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Orientador: Wang Binseng Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica Resumo: O diagnóstico clinico no campo neurológico tem-se baseado quase sempre na historia, no exame físico, na visualização de estruturas anatômica com emprego de equipamentos de custo muito elevado, e na descrição do distúrbio neurológico pelo próprio paciente. Potenciais evocados são potenciais elétrico registráveis perto de grupos de células nervosas após a aplicação de um estímulo externo apropriado a cada sistema sensorial. Estes potenciais, registrado de maneira não-invasiva, permitiram o avanço nos estudos e testes das funções sensoriais, bem como a criação de procedimentos clinicamente aplicáveis para diagnóstico de distúrbios neurosensoriais. Os potenciais evocados possuem pequena amplitude (variam de dê cimos de microvolts a dezenas de microvolts) e, portanto, são freqüentemente me carados pela presença de outros potenciais (neurais e não-neurais) de maior amplitude. Por ter relação sinal/ruído muito baixa, é necessária a utilização d instrumentos onde são implementadas técnicas de processamento de sinais para s extrair o sinal do ruído. Neste trabalho, apresenta-se o projeto e a construção de um equipamento (promediador) baseado num microprocessador de 8 bits, tendo sido implementado o método do cálculo da média síncrona, ou promediação. O promediado consiste de: um microprocessador 8085A; 2k "bytes" de memória EPROM onde estão armazenados os programas residentes; 3k "bytes" de memória RAM (memória de da dos da soma ou da média); 3 interfaces de comunicação paralela (8255); um sistema de conversão A/D, com circuito gerador de freqüências de amostragem, amplificador e filtro; e um sistema de conversão D/A com interface de saída e circuito de controle do sistema. A cada estimulo aplicado, são adquiridos e processados 512 pontos da resposta a este estímulo. O número de estímulos aplicados é mostrado nu "display" de 5 dígitos e o resultado do segmento médio ou da soma intermediaria e mostrado num osciloscópio. 0 usuário pode solicitar: a) zerar memória; b) iniciar processamento; c) parar processamento; e d) calcular média. onde ainda se lecionar: a) ganho do amplificador; b) freqüência de corte do filtro; c) freqüência de amostragem; d) número de estímulos; e) escalamento do sinal de saí da; e f) atraso do sinal de sincronismo vindo do estimulador. Além dos testes de bancada, com sinais artificiais, o protótipo foi testado com animais e com voluntários, sendo obtidos potenciais evocados aditivos de tronco cerebral e de córtex não-específico. Os resultados obtidos são praticamente análogos aos obtidos com um equipamento importado, demonstrando que foram atingidos os objetivos propostos. Abstract: Clinical diagnosis in neurology have been based almost always on medical history, physical examination, imaging of anatomical structures through expensive equipments, and description of neurological deficiencies by the patient himself. Evoked potentials are electric potentials which can be recorded from nerve cells after the application of external stimulus, appropriate to each sensory system. These potentials, obtained noninvasively, brought progress in studies and testing of sensory functions, as well as the invention of clinical procedures applicable to the diagnosis of neurosensory disorders. Evoked potentials have small amplitudes (from fraction of microvolts to tens of microvolts), thus are often masked by other potentials (neural and nonneural) of greater amplitude. Being small the signal-to-noise ratio, it is necessary to use specialized instrumentation to extract the former from the latter. In this thesis is presented the design and the construction o a equipment (averager) based on an 8-bit microprocessor, on which the method of synchronous averaging was implemented. The averager is composed of: an 808 microprocessor, 2k bytes of EPROM (where is located the system software), 3k bytes of RAM (for data), 3 parallel communication interface (8255), a 10-bit A converter system, a circuitry for generating sampling frequencies, amplifiers and filters, a D/A converter with output interface, and a control circuit. After application of each stimulus, 512 points of response an acquired and processed. The number of stimuli applied is presented on a 5-dig display, and the result of averaging, or the intermediate summation, is presented on an oscilloscope. The user can: a) zero the contents of the memory; b) initiate the processing; c) stop the processing, and d) compute the average. Furthermore, he can also select: a) the gain of the amplifier; b) the cut-off frequency of the filters; c) the sampling frequencies; d) the number of stimuli to be processed; e) the output gain; and f) the delay to be applied after the arrival of the synchronizing signal. Besides bench tests with artificial signals, the prototype we tested with animals and volunteers, with the recording of auditory evoked potentials from the brainstem and nonspecific cortex. The results obtained are very similar to those obtained with an imported equipment, thus proving that the goals proposed were met. Mestrado Mestre em Engenharia Elétrica

Os métodos para beamforming adaptativo tem apresentado resultados positivos, melhorando a qualidade dasimagens médicas por ultrassom, em comparação com a técnicanão adaptativa Delay and Sum (DAS). O Generalized SidelobeCanceler (GSC) pode melhorar consideravelmente a resoluçãolateral das imagens médicas de ultrassom, mas o contraste daimagem não é satisfatório. O EBMV (Eigenspace BasedMinimum Variance) é um beamformer adaptável que podesuprimir uma grande parte do ruído e fornecer imagens commaior contraste e resolução em comparação com o DAS e obeamformer de mínima variância (MVB). Neste trabalho, foiaplicado o EBMV para imagens de ultrassom de ondas planas. Os dados de eco simulados foram obtidos no site Plane WaveChallenge em Medical Ultrasound Imaging (PICMUS).Os dados in vivo foram adquiridos usando um equipamentoVerasonics Vantage 256 usando um transdutor de elementosL11-4v 128. Os resultados obtidos foram comparados com DAS e MVGSC e mostraram melhora da resolução lateral.&nbsp

Introduction Although the envelope detection is a widely used method in medical ultrasound (US) imaging to demodulate the amplitude of the received echo signal before any back-end processing, novel hardware-based approaches have been proposed for reducing its computational cost and complexity. In this paper, we present the modeling and FPGA implementation of an efficient envelope detector based on a Hilbert Transform (HT) approximation for US imaging applications. Method The proposed model exploits both the symmetry and the alternating zero-valued coefficients of a HT finite impulse response (FIR) filter to generate the in-phase and quadrature components that are necessary for the envelope computation. The hardware design was synthesized for a Stratix IV FPGA, by using the Simulink and the integrated DSP Builder toolbox, and implemented on a Terasic DE4-230 board. The accuracy of our algorithm was evaluated by the normalized root mean square error (NRMSE) cost function in comparison with the conventional method based on the absolute value of the discrete-time analytic signal via FFT. Results An excellent agreement was achieved between the theoretical simulations with the experimental result. The NRMSE was 0.42% and the overall FPGA utilization was less than 1.5%. Additionally, the proposed envelope detector is capable of generating envelope data at every FPGA clock cycle after 19 (0.48 µs) cycles of latency. Conclusion The presented results corroborate the simplicity, flexibility and efficiency of our model for generating US envelope data in real-time, while reducing the hardware cost by up to 75%.

IntroductionIn this paper, we present the initial results of a fully programmable 128-channel FPGA and PC-based system that has been developed for medical ultrasound (US) imaging research in our University laboratory (Federal University of Technology - Paraná, Brazil).MethodsIn order to demonstrate the feasibility of the US research system, two applications involving unfocused plane wave transmission and conventional B-mode beamforming were evaluated using a commercial tissue-mimicking phantom and a 3.2 MHz 128-element convex array transducer.ResultsTesting results show that the hardware platform is able to synthesize arbitrary pulses up to 100 Vpp with second order harmonic distortion below 80 dB. For the first application, a 41-tap digital FIR bandpass filter was applied to the acquired RF echoes, sampled at 40 MHz with 12-bit resolution, to improve the noise suppression. In the second application, after offline apodization weighting, filtering, delay-and-sum processing, envelope detection, log compression and scan conversion, the reconstructed B-mode image is displayed over a 50 dB range.DiscussionThe presented results indicate that the open US imaging system can be used to support different ultrasonic transmission and reception strategies, which typically cannot be implemented in conventional data flow architectures that are mainly based on hardware.

INTRODUÇÃO: A circulação extracorpórea (CEC) é indispensável para a maioria das operações cardíacas, mas causa danos significantes ao sangue, dentre eles a hemólise. OBJETIVO: Quantificar as taxas de hemólise em diferentes tempos nas operações para revascularização do miocárdio com uso de CEC. MÉTODOS: Foram medidas as taxas de hemólise de 22 pacientes em 6 tempos distintos durante a revascularização do miocárdio com uso de CEC: T0 - antes do início da CEC, T1 - 5 minutos após o início da CEC, T2 - com 30 minutos de CEC, T3 - imediatamente antes do despinçamento da aorta, T4 - imediatamente antes da passagem do volume residual para o paciente e T5 - 5 minutos após o término da passagem do volume residual para o paciente. Foram calculadas as taxas de hemólise entre os intervalos de tempo: T0-T1; T1-T2; T2-T3; T3-T4 e T4-T5. RESULTADOS: Os primeiros 5 minutos após a CEC demonstraram maior taxa de hemólise (P = 0,0003) em comparação às outras taxas calculadas, representando 29% da hemólise total até T4 (imediatamente antes da passagem do volume residual para o paciente). CONCLUSÃO: Não foram observadas variações significantes nas taxas de hemólise durante a aspiração na raiz da aorta (P > 0,38) nem com o procedimento utilizado para a passagem do volume residual de sangue no circuito para os pacientes. INTRODUCTION: Extracorporeal circulation (EC) is very important in cardiac surgery but causes significant damage to the blood, including hemolysis. OBJECTIVE: To quantify the rate of hemolysis at different times during EC in elective coronary artery bypass grafting. METHODS: We measured rates of hemolysis of 22 patients at 6 different times during myocardial revascularization during EC: T0 - before the start of EC, T1 - five minutes after of the EC initiation, T2 - 30 minutes of EC, T3 - immediately before the aortic unclamping, T4 - immediately before passage of the residual volume to the patient and T5 - five minutes after the passage of the residual volume to the patient. Rates of hemolysis were calculated between the intervals of time: T0-T1; T1-T2; T2-T3; T3-T4 and T4-T5. RESULTS: The first 5 minutes after the EC showed the highest rate of hemolysis (P = 0.0003) compared to the others calculated rates, representing 29% of the total haemolysis until T4 (Immediately before passage of the residual volume to the patient). CONCLUSION: There were no significant changes in the rate of hemolysis during the suction in the aortic root (P> 0.38), nor with the procedure used for the passage of the residual volume of blood in the circuit to the patient.