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Conjunction of Bioelectrical Impedance Spectroscopy with Archie’s Law to Characterize Scaffolds Porosity 9th

Conjunction of Bioelectrical Impedance Spectroscopy with Arc...

9th Latin American Congress on biomedical engineering, CLAIB 2022 and 28th Brazilian Congress on biomedical engineering, CBEB 2022

作者： Barbosa, Carlos Vinicius Nascimento de Souza, Marcio Nogueira Pino, Alexandre Visintainer COPPE/UFRJ/Biomedical Engineering Program Rio de Janeiro Brazil

ISBN: (纸本)9783031494000

Tissue engineering is a multidisciplinary field that uses two and three dimensional structures called scaffolds to create a physical support for growth, gas change and nutrition of the cell. Those scaffolds can be synthetic, biological or a combination of both types of material, but the porosity, the interconnectivity of pores and pore size are among the most important physical parameters of the scaffolds. The estimation of these characteristics is still a challenge in Tissue engineering, as it involves techniques and methods that need to be non-toxic and non-destructive, and that must operate in structures with dimensions of the order of micrometers (µm). The bioimpedance spectroscopy (bis) technique has been reported as a potential non-invasive monitoring of scaffold porosity and biological tissue growth. This work aims to study how bioimpedance spectroscopy in conjunction with Archiés law data can be used to characterize the porosity and pore connectivity of 3D cellular structures. © 2024, The Author(s), under exclusive license to Springer Nature Switzerland AG.

关键词： Pore size

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Singular spectrum analysis – an automatic detection technique for mean scatterer spacing estimation using ultrasound signals

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Research on biomedical engineering 2025年第2期41卷 1-16页

作者： Kauati, Adriana Cortela, Guillermo de Campos, Marcello L. R. Pereira, Wagner C. A. Programa de Pós-graduação em Engenharia Elétrica e Computação – CECE/UNIOESTE PR Foz do Iguaçu85870 650 Brazil Laboratorio de Acústica Ultrasónora – FCien/UdelaR Montevideo Uruguay Electrical Engineering Program – COPPE/UFRJ RJ Rio de Janeiro21941 - 914 Brazil Biomedical Engineering Program – COPPE/UFRJ RJ Rio de Janeiro21941 - 914 Brazil

Purpose: The article proposes an automated method for estimating mean scatterer spacing (MSS) in biological tissues using ultrasound signals. It employs singular spectrum analysis (SSA) with a novel entropy-based criterion to enhance accuracy and eliminate the need for manual parameter tuning. The method is validated using both simulated and real signals, demonstrating its effectiveness in detecting microstructural changes in tissues. Methods: The proposed SSA + entropy method estimates the MSS from ultrasound signals using SSA combined with a relative entropy-based criterion. This approach determines the optimal number of eigenvector pairs to reconstruct the periodic part of the signal by identifying the minimum in the entropy curve—a point that corresponds to the number of underlying periodic components, even in noisy conditions. For experimental validation, ex vivo bovine skeletal muscle was analyzed. RF data were collected at a controlled temperature of using a 3.5-MHz transducer. The MSS results obtained via SSA were also independently verified using microscopy and image analysis of muscle fiber spacing, confirming the effectiveness of the entropy-based SSA approach. Results: The MSS estimation method's accuracy decreases as jitter or Ad noise levels increase, with the method performing well when the estimated MSS is within 10% of the true value. Additionally, the standard deviation of MSS estimates increases as Ad levels and jitter values rise. In phantom experiments, MSS was measured using different transducer frequencies with varying results at each frequency. When applied to ex vivo bovine skeletal muscle tissue, the MSS estimation was validated using both RF and imaging methods, with three consistent groups of MSS values observed, confirming the method's applicability and reliability. Conclusion: The proposed method combines SSA and entropy to automatically estimate medium periodicity in ultrasound, eliminating the need for operator intervention. It succes

关键词： Image analysis

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Thermographic Analysis in a Multilayer Medium Cortical Bone/Cancellous Bone/Bone Cement Heated by Therapeutic Ultrasound 9th

Thermographic Analysis in a Multilayer Medium Cortical Bone/...

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9th Latin American Congress on biomedical engineering, CLAIB 2022 and 28th Brazilian Congress on biomedical engineering, CBEB 2022

作者： dos Santos, B.T.M.T. de Oliveira, L.V.C. Lopes, A.M.C. Pereira, L.F. Pereira, A.J.F. Omena, T.P. Pereira, W.C.A. UFRJ/COPPE/ Biomedical Engineering Program Av. Horácio Macedo 2030 Centro de Tecnologia COPPE/UFRJ Bloco H S. 327 Rio de Janeiro Brazil UFRJ/Physiotherapy Department Rio de Janeiro Brazil University Centre Serra Dos Órgãos Rio de Janeiro Brazil

ISBN: (纸本)9783031494000

The thermal effects of therapeutic ultrasound are used to produce analgesia or reduce inflammation in biological tissues. However, it is contraindicated on regions with cemented prostheses, due to the supposed heating of it. The present study aims to evaluate the heating pattern in a multilayer medium, using cortical bone phantom, cancellous bone phantoms and, bone cement specimen. It was observed that the cancellous bone phantom was the one that warmed the most, reaching an average temperature of 33.89 ± 1.89 ºC, while the bone cement specimen barely changed. In the multilayer medium, the heating pattern was more superficial than expected. More studies are needed to elucidate the influence of application time and intensity in ultrasonic irradiation in places with the presence of bone cement in treatment protocols. © 2024, The Author(s), under exclusive license to Springer Nature Switzerland AG.

关键词： Phantoms

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FEM modeling and simulation of broadband ultrasonic transducers with randomized inhomogeneous backing material

arXiv

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arXiv 2022年

作者： Moreno, Eduardo Pereira, Wagner C.A. von Kruger, Marco Antonio Leija, Lorenzo Ramos, Antonio Ultrasonic Group ICIMAF Calle 15 No 551 Vedado La Habana Cuba Biomedical Engineering Program COPPE UFRJ 2030 Horacio Macedo Ave Rio de Janeiro21941-914 Brazil Department of Electrical Engineering Bioelectronics Section Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional Cinvestav México City Mexico R&D Group "Sistemas y Tecnologías Ultrasónicas" Instituto de Tecnologías Físicas y de la Información CSIC Madrid Spain

A FEM application for the accurate design of composite backing of ultrasonic transducers is presented. The idea is to obtain the dependence between the volume ratio of the tungsten powder in an epoxy matrix used as a backing and the final pulsed RF signal emitted by the backed transducer. An inhomogeneous material model for the backing was adopted instead of the classic complex geometrical FEM. The model was developed in Comsol 5.5 using two of its physics interfaces. The first based on classic FEM or continuous Galerkin for ultrasonic propagation in the backing and the second based on a discontinuous Galerkin option for fluid pulsed propagation. In this way it is possible to avoid the use of an impedance-based model. The calculations for the resulting bandwidth are good enough as predicted for Desilets for the 1D case by using the KLM circuital model. We worked in a 2D space, where the transducer face vibration is far away from the assumed piston-like considered by the unidimensional KLM model. © 2022, CC BY.

关键词： Finite element method

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Tracing the shear modulus of blood plasma during clotting and based on acoustic radiation force induced vibration of an embedded sphere

Tracing the shear modulus of blood plasma during clotting an...

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2017 IEEE International Ultrasonics Symposium, IUS 2017

作者： Silva Costa, Jose Francisco Machado, Joao Carlos Guilherme Crossetti Parcero João Carlos Machado Biomedical Engineering Program COPPE/UFRJ Rio de Janeiro Brazil Post-Graduation Program in Surgical Sciences Dept. of Surgery/School of Medicine/UFRJ Rio de Janeiro Brazil

ISBN: (纸本)9781538633830

During coagulation, blood changes from liquid to gel, and the clot viscoelastic properties continue modifying until fibrinolysis. Ultrasound (US) was used in this work to trace the time-changing shear modulus, μ, during plasma clotting, based on the vibration signature induced by an impulsive acoustic radiation force (iARF) on a sphere embedded in a plasma sample along its clotting process induced based on the aPTT (activated partial thromboplastin time) assay. An US push system transmitted bursts of US pulses (2.03 MHz, 1000 cycles and 1.25 Hz of pulse repetition frequency) to generate an iARF on the glass sphere (4.0 mm in diameter and density of 2500 kg/m3), which displacement was monitored by a 5.0 MHz US pulse-echo probing system. The relative delays between the rf-echo signals from the sphere yielded the signal representing the sphere damped oscillation that was fitted with a theoretical-model displacement function whose unknowns are the iARF amplitude and the medium μ and shear viscosity, η. The method was repeated five times and the time-changing mean μ was determined along 2100 s of the clotting process. During the first 15 s μ remained at 20 Pa and then varied rapidly until 60 s, at a rate of 1.9 Pa/s. Between 60 and 800 s, μ varied at a rate of 0.2 Pa/s. From 800 to 2100 s μ remained stable at about 280 Pa. The interval of fast changing μ corresponds to the fibrin formation period and comprehends the clotting time of 25s typically obtained with the aPTT assay for control plasma. © 2017 IEEE.

关键词： Coagulation Plasmas Acoustics Force Glass Transducers

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Development of a Calorimeter to Evaluate Heating of Soft Tissue Phantom Irradiated by Physiotherapeutic Ultrasound Beams

Development of a Calorimeter to Evaluate Heating of Soft Tis...

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Global Medical engineering Physics Exchanges/Pan American Health Care Exchanges Conference

作者： T. P. Omena M. A. von Krüger W. C. A. Pereira Department of Physiotherapy College of Medicine - UFRJ Rio de Janeiro Brazil Program of Biomedical Engineering COPPE-UFRJ Rio de Janeiro Brazil

ISBN: (纸本)9781509024872

Calorimeters can be employed in the measurement of temperature of a medium heated by ultrasound beams. The temperature elevation is attributed to the absorbed energy at a depth of a biological tissue mimicking phantom. The goal of the work is to present the project and construction of a calorimeter that serves as a tool to study heating protocols of ultrasound therapy. Some experimental results are also presented.

关键词： Ultrasound Calorimeter Phantom

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A Thermochromic Test Body and its Relationship with the Effective Radiation Area (ERA) of Therapeutic Ultrasound Devices

A Thermochromic Test Body and its Relationship with the Effe...

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Global Medical engineering Physics Exchanges/Pan American Health Care Exchanges Conference

作者： R. M. Costa T. P. Omena M. A. von Krüger W. C. A. Pereira National Institute of Cancer Rio de Janeiro Brazil Biomedical Engineering Program COPPE-UFRJ Rio de Janeiro Brazil

ISBN: (纸本)9781509024872

This paper presents a thermochromic test body to qualitative evaluate the Effective Radiation Area (ERA) of Therapeutic Ultrasound (TUS) devices. The thermal areas produced by three transducers are measured and compared to the ERA of the same transducers measured according to the IEC 61689 standard. A linear relationship was obtained between both kinds of areas suggesting that a quantitative relation can be found and used to easily monitor TUS working conditions.

关键词： Ultrasound calibration thermochromic Effective Radiation Area silicone

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Evaluation of acoustic and thermal properties of gellan-gum phantom to mimic biological tissue

Evaluation of acoustic and thermal properties of gellan-gum ...

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Pan American Health Care Exchanges, PAHCE

作者： G. Cortela K. M. Lima L. E. Maggi C. Negreira W. C.A. Pereira Laboratorio de Acustica Ultrasonora UdelaR Mvd Uruguay Biomedical Engineering Program COPPE/UFRJ RJ Brazil CCBN/UFAC AC Brazil

A hydrogel-based (gellan gum) tissue mimicking material (TMM) was developed. Its acoustic and thermal properties were characterized. The hydrogel was combined with different sizes of glass spheres. The acoustic properties (attenuation coefficient and the speed of sound) were obtained as a function of the temperature range 20 to 45° C. Specific heat was determined experimentally by the standard mixture method for the same temperature range. The attenuation coefficient presented a quasi-linear dependence on the frequency, such as the most of mammalian tissues. The mean value was 0.59f 0,85 dB·cm-1, at 30° C from 1 to 10MHz. The results suggest that the developed TMM has potential for several applications: development of standard dosimetry techniques, validation numerical models and determination the efficacy of hyperthermia devices.

关键词： Ultrasonic imaging Temperature measurement Attenuation Acoustics Ultrasonic variables measurement Biological tissues Heating

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Effect of the ultrasound wave propagation regime in the heat source term of Penne’s bio-heat transfer equation

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Proceedings of Meetings on Acoustics 2016年第1期28卷

作者： Guillermo Cortela Carlos Negreira Wagner C. A. Pereira 1Laboratorio de Acústica Ultrasónica University of the Republic Montevideo Uruguay gcortela@fisica.edu.uy carlosn@fisica.edu.uy 2Biomedical Engineering Program COPPE/Federal University of Rio de Janeiro Brazilwagner@peb.ufrj.br

This work analyses the influence of the ultrasound wave propagation regime on the temperature increase on biological media. Simulated and experimental temperature values from bovine ex-vivo tissue in two different depths, 5 and 40 mm, respectively smaller and bigger than the mean free propagation path (ℓS = 8.52 mm), are obtained. Temperature curves measured during US therapeutic application (High Intensity Therapeutic Ultrasound, HITU, 1 MHz, 1.5 – 2.0 Wcm−2) for 10 min, are compared to simulated ones using the Penne’s bio-heat transfer equation (BHTE) at the same frequency and intensities and using the standard source term (ultrasonic absorption coefficient). At 5 mm, estimated and measured temperature diverge no more than 1%, while at 40 mm, when the scattering starts being not negligible, the simulated temperature is 20% smaller than the measured one. The results indicate that absorption increases when the wave propagation regime changes for depths greater than the ℓS value.

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An interpolation-free and fitting-less sub-sample time-delay estimation algorithm

An interpolation-free and fitting-less sub-sample time-delay...

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International Conference on Health Informatics, ICHI 2013

作者： Teixeira, César A. Ruano, M. Graça Pereira, W.C.A. Centre for Informatics and Systems University of Coimbra Coimbra Portugal University of Algarve Faro Portugal Biomedical Engineering Program - COPPE Federal University of Rio de Janeiro-UFRJ Rio de Janeiro Brazil

ISBN: (纸本)9783319030043

In this paper we propose a new algorithm for sub-sample time-delay estimation between two discrete-time signals. The new algorithm operates just over the discrete-time signals without the need for interpolation or fitting. The proposed method is compared with a method based on spline fitting, and that is referred to outperform other methods over a broader set of conditions (Viola&Walker, 2005). The new approach, besides presenting a low computational cost (70% less), seemed to outperforms the spline approach in situations of high noise levels (typically signal-to noise ratios smaller than 20dB). © 2014, Springer International Publishing Switzerland.

关键词： Interpolation

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