Abstract 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%.

Abstract: Introduction Diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) combine magnetic resonance imaging (MRI) techniques and diffusion measures. In DWI, the contrast is defined by microscopic motion of water protons. Nowadays, DWI has become important for early diagnostic of acute stroke. DTI images are calculated from DWI images acquired in at least six directions, which give information of diffusion directionality, making it possible to reconstruct axonal or muscle fiber images. Both techniques have been applied to study body structures in healthy and pathological conditions. Currently, it is known that these images and derived parameters are quite sensitive to factors related to acquisition and processing. Magnetic field inhomogeneity, susceptibility, chemical shift, radiofrequency (RF) interference, eddy currents and low signal-to-noise ratio (SNR) can have a more harmful effect in diffusion data than in T1- or T2-weighted image data. However, even today there are not reference phantoms and guidelines for DWI or DTI quality control (QC). Review Proposals for construction and use of DWI and DTI QC phantoms can be found in literature. DWI have been evaluated using containers filled by gel or liquid with tissue-like MRI properties, as well as using microfabricated devices. DTI acquisitions also have been checked with these devices or using natural or artificial fiber structures. The head phantom from American College of Radiology (ACR) is also pointed out as an alternative for DTI QC. This article brings a discussion about proposed DWI and DTI phantoms, challenges involved and future perspectives for standardization of DWI and DTI QC.

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.

Objetivo:Analisar quais os principais fatores que influenciam na massa óssea de crianças e adolescentes avaliada pelo ultrassom quantitativo (QUS) de falanges.Fonte de dados:Foi realizada revisão sistemática da literatura, de acordo com o método Prisma, com buscas nas bases de dados do Pubmed/Medline, Bireme e Scielo, referente ao período de 2001 a 2012, nos idiomas inglês e português, utilizando os descritores children, adolescent, ultrassonography finger phalanges, quantitative ultrasound of phalanges, phalangeal quantitative ultrasound.Síntese dos dados:Foram incluídos 21 artigos. As meninas apresentaram no QUS valores de Amplitude Dependent Speed of Sound (AD-SoS) superiores aos meninos durante o desenvolvimento puberal. Os valores dos parâmetros do QUS de falanges aumentaram com o incremento do estádio maturacional, assim como ocorre com o Dual-energy X-ray Absorptiometry (DXA). Variáveis antropométricas, como idade, peso, estatura, índice de massa corporal (IMC) e massa magra, demonstraram correlações positivas com os valores do QUS de falanges. A atividade física também demonstrou estar positivamente relacionada ao aumento da massa óssea. Fatores como etnia, genética, ingestão calórica e perfil socioeconômico ainda não mostraram relação conclusiva e necessitam um número maior de estudos.Conclusões:O QUS de falanges é um método indicado para avaliar a progressiva aquisição da massa óssea durante o crescimento e a maturação dos indivíduos em fase escolar, por acompanhar as alterações que ocorrem com o aumento da idade e do estádio puberal. Observouse influência positiva, principalmente das variáveis de sexo, maturação, estatura, peso e IMC, sendo seus dados semelhantes quando comparados ao método padrão-ouro, o DXA.

Objective:To analyze the main factors that influence bone mass in children and teenagers assessed by quantitative ultrasound (QUS) of the phalanges.Data source:A systematic literature review was performed according to the PRISMA method with searches in databases Pubmed/Medline, SciELO and Bireme for the period 2001-2012, in English and Portuguese languages, using the keywords: children, teenagers, adolescent, ultrasound finger phalanges, quantitative ultrasound of phalanges, phalangeal quantitative ultrasound.Data synthesis:21 articles were included. Girls had, in QUS, Amplitude Dependent Speed of Sound (AD-SoS) values higher than boys during pubertal development. The values of the parameters of QUS of the phalanges and dual-energy X-ray Absorptiometry (DXA) increased with the increase of the maturational stage. Anthropometric variables such as age, weight, height, body mass index (BMI), lean mass showed positive correlations with the values of QUS of the phalanges. Physical activity has also been shown to be positively associated with increased bone mass. Factors such as ethnicity, genetics, caloric intake and socioeconomic profile have not yet shown a conclusive relationship and need a larger number of studies.Conclusions:QUS of the phalanges is a method used to evaluate the progressive acquisition of bone mass during growth and maturation of individuals in school phase, by monitoring changes that occur with increasing age and pubertal stage. There were mainly positive influences variables of sex, maturity, height, weight and BMI, with similar data when compared to the gold standard method, the DXA.

INTRODUÇÃO: A caracterização hidrodinâmica in vitro de próteses de válvulas cardíacas fornece informações importantes quanto ao seu funcionamento, sobretudo se realizada por meio de métodos não-invasivos de anemometria. Uma vez obtidos os perfis de velocidade para cada válvula, é possível compará-las quanto ao seu desempenho hidrodinâmico. Neste primeiro estudo experimental de anemometria laser com válvulas mecânicas, as simulações foram realizadas em bancada de testes para escoamento permanente. OBJETIVO: Comparar perfis de velocidade unidimensional no plano central de duas próteses aórticas de duplo folheto St. Jude (modelos AGN 21 - 751 e 21 AJ - 501) submetidas a um regime de fluxo permanente, para quatro seções distintas, três à jusante e uma à montante. MÉTODOS: Proporcionar condições de similaridade para o escoamento através de cada prótese, por meio de bancada hidrodinâmica para escoamento permanente (água, à vazão de 17 L/min.) e, por meio de anemometria laser unidimensional, obter os perfis de velocidades para as mesmas seções e varreduras. RESULTADOS: Verificou-se que as maiores velocidades correspondem à prótese de diâmetro interno menor e que as instabilidades do fluxo são maiores à medida que a seção de interesse encontra-se mais próxima da válvula. Também foram verificadas as regiões de recirculação, de estagnação do fluxo e de baixa pressão, além dos picos de velocidade para o escoamento em questão. CONCLUSÕES: Sob o aspecto hidrodinâmico e para todas as seções de interesse, foi possível concluir a preferência da válvula de modelo AGN 21 - 751 (RegentTM) sobre a 21 AJ - 501 (Master Series). Os resultados obtidos permitiram escolher, para os próximos trabalhos, um foco de estudo mais específico para regiões concretas dessas próteses.

INTRODUCTION: In vitro hydrodynamic characterization of prosthetic heart valves provides important information regarding their operation, especially if performed by noninvasive techniques of anemometry. Once velocity profiles for each valve are provided, it is possible to compare them in terms of hydrodynamic performance. In this first experimental study using laser doppler anemometry with mechanical valves, the simulations were performed at a steady flow workbench. OBJECTIVE: To compare unidimensional velocity profiles at the central plane of two bi-leaflet aortic prosthesis from St. Jude (AGN 21 - 751 and 21 AJ - 501 models) exposed to a steady flow regime, on four distinct sections, three downstream and one upstream. METHODS: To provide similar conditions for the flow through each prosthesis by a steady flow workbench (water, flow rate of 17L/min.) and, for the same sections and sweeps, to obtain the velocity profiles of each heart valve by unidimensional measurements. RESULTS: It was found that higher velocities correspond to the prosthesis with smaller inner diameter and instabilities of flow are larger as the section of interest is closer to the valve. Regions of recirculation, stagnation of flow, low pressure, and flow peak velocities were also found. CONCLUSIONS: Considering the hydrodynamic aspect and for every section measured, it could be concluded that the prosthesis model AGN 21 - 751 (RegentTM) is superior to the 21 AJ - 501 model (Master Series). Based on the results, future studies can choose to focus on specific regions of the these valves.

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.

INTRODUÇÃO: Bombas de roletes desempenham um papel importante na circulação extracorpórea. No entanto, a oclusão dos roletes das bombas deve ser realizada de forma adequada e estas podem ser ajustadas, principalmente por dois métodos: estático e dinâmico. OBJETIVO: Investigar como os perfusionistas brasileiros ajustam as bombas de rolete arterial em seus serviços e testar o uso de um Dispositivo Auxiliar de Calibração que facilita o ajuste pelo método de calibração dinâmica. MÉTODOS: Foi instalada uma bomba de roletes com os acessórios necessários para a realização de sua calibração pelos métodos de velocidade de queda (calibração estática) e calibração dinâmica durante o XXVIII Congresso Brasileiro de Circulação Extracorpórea. Foi solicitado aos perfusionistas que ajustassem uma bomba de roletes conforme procedimento normalmente utilizado em seu serviço. Após cada regulagem, foi medida a respectiva pressão pelo método de calibração dinâmica com o auxílio do dispositivo. O projeto foi aprovado pelo Comitê de Ética em Pesquisa da UNICAMP, sob Nº 1144/2010. RESULTADOS: Participaram da pesquisa 56 perfusionistas. A média das 56 medidas de pressão de calibração dinâmica foi 434 ± 214 mmHg; 76% das medidas realizadas ficaram no intervalo preconizado para o uso da técnica de calibração dinâmica (entre 150 e 500 mmHg). CONCLUSÃO: Os perfusionistas brasileiros tendem a calibrar bombas de roletes com ajustes menos oclusivos. As amplitudes das medidas de pressão de calibração dinâmica tendem a ser menores para perfusionistas mais experientes. O dispositivo pode ser utilizado por perfusionistas para ajustar bombas de roletes com maior precisão e, principalmente, repetitividade e em alguns minutos.

INTRODUCTION: Roller pumps play an important role in extracorporeal circulation. However, occlusion of the rollers should be adequately performed and this can be adjusted mainly by two methods: static and dynamic. OBJECTIVE: To investigate how the Brazilian perfusionists adjust arterial roller pumps in their services and evaluate the application of a Device to Assist Calibration (DAC) that facilitates roller adjustment by the dynamic calibration method. METHODS: We installed a roller pump with accessories to perform adjustment by drop rate (static calibration) and dynamic calibration methods during the XXVIII Brazilian Congress of Extracorporeal Circulation. Perfusionists were asked to adjust the roller pump according to the procedure they usually do in their service. After each adjustment pressure was measured by dynamic calibration method with DAC. The research was approved by the Research Ethics Committee of UNICAMP, Nº 1144/2010. RESULTS: There were 56 perfusionists in this study. Pressure average of 56 measurements of dynamic calibration was 434 ± 214 mmHg; 76% of measurements were within the recommended range for the use of the dynamic calibration method (between 150 and 500 mmHg). CONCLUSION: Brazilian perfusionists tend to adjust roller pumps with less occlusive settings. The amplitudes of the dynamic calibration pressure tend to be smaller for more experienced perfusionists because their skills increase with time. The device can be used by the perfusionist to adjust roller pumps with greater accuracy and mainly repeatability in few minutes.

OBJETIVO: Um dos maiores danos causados pela oclusão em bombas de rolete é a hemólise. Estudos comparativos entre bomba de roletes com ajustes não oclusivos e bombas centrífugas têm sido realizados nas últimas décadas na tentativa de desenvolver novos produtos e ajustes que causem menos trauma aos elementos figurados do sangue. Comumente as bombas de rolete são ajustadas pelo método estático devido à preocupação com fluxos variáveis que podem ocorrer com ajustes não oclusivos. Folga excessiva nos roletes permite refluxo e pode acarretar erros no cálculo dos fluxos pela rotação da bomba, de acordo com os dispositivos adicionados ao circuito e a resistência sistêmica do paciente. O objetivo desse trabalho é avaliar o refluxo causado por dois modelos de bombas de rolete em aspirador de sangue e em reservatório de cardiotomia. MÉTODOS: A visualização do refluxo foi realizada em aspirador de sangue e, em reservatório de cardiotomia, a visualização foi acompanhada de respectiva medida. Foram testados dois modelos de bombas de rolete de diferentes fabricantes, ajustadas pelo método de velocidade de queda e calibração dinâmica. Os testes foram conduzidos com tubos de silicone de 3/8 x 1/16 e 1/2 x 3/32 polegadas de diâmetro em água e solução análoga ao sangue. RESULTADOS: Foram registrados visualmente os refluxos em aspirador de sangue e em reservatório de cardiotomia, com respectiva medida dos valores. As bombas apresentaram diferenças nos refluxos medidos ajustadas pelo método de calibração dinâmica. A bomba #2 apresentou refluxo, ajustada totalmente ocluída. CONCLUSÃO: Os refluxos medidos nos dois modelos de bomba apresentaram diferenças (P<0,008). Os resultados indicam diferenças nas características construtivas ocasionadas pelo processo de fabricação, projeto ou possíveis desgastes. Ajustes pouco oclusivos podem proporcionar variações nos fluxos com a resistência adicionada ao circuito, com dificuldade de correção do fluxo pelo incremento da rotação.

OBJECTIVE: One of the major damage caused by occlusion in roller pumps is hemolysis. Comparative studies between roller pump with adjustments non occlusive and centrifugal pumps have been made in recent decades in an attempt to develop new products and adjustments that cause fewer traumas to the figurative elements of blood. Usually the roller pumps are adjusted by the static method due to concern variables flow that can occur with non-occlusive settings. Excessive slack in the rollers provoke back flow and can provides errors in the calculation of flow by the rotation of the pump, according to the devices added to the circuit and the systemic resistance of the patient. The objective of this study is to evaluate the back flow caused by two types of roller pumps in blood aspirator and cardiotomy reservoir. METHOD: Back flow visualization was performed in blood aspirator and cardiotomy reservoir. It was tested two different models of roller pumps, adjusted by drop rate and dynamic calibration. The tests were conducted with silicone tubes of 3/8 x 1/16 e 1/2 x 3/32 inches in diameter in water and solution similar to blood. RESULTS: We recorded back flow visually in blood aspirator and in cardiotomy reservoir with their measure of values. The pumps had differences in refluxes measured adjusted by the dynamic calibration method. Pump#2 presents back flow adjusted fully occluded. CONCLUSION: The back flow measured in two models of pump present differences (P <0.008). The results indicate differences in its characteristics caused by the process of manufacturing, design or possible wear. Non-occlusive adjustments may cause variations in flow with the increase of resistance added to the circuit, with difficulty to fix the flow by increasing the rotation.