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Gas vesicle isolated from microorganisms to act as ultrasound contrast agent

Research on biomedical engineering 2021年第1期37卷 1-7页

作者： Garrute, Felipe Vianna Machado, João Carlos Biomedical Engineering Program-COPPE Federal University of Rio de Janeiro Horácio Macedo Ave. 2030 Center of Technology Block H Room 327 Rio de JaneiroRJ21941-914 Brazil Post-graduate Program in Surgical Sciences Department of Surgery School of Medicine Federal University of Rio de Janeiro Carlos Chagas Filho Ave. 373 Health Sciences Center Block K Room 49 Rio de JaneiroRJ21941-902 Brazil

Purpose: Ultrasound contrast agent (UCA), used to enhance the contrast in ultrasonography, consists of microbubbles filled with an inert gas and encapsulated with a protein or a lipidic-stabilize membrane. The UCAs are able to resonate when exposed to ultrasound waves and to generate an echo-acoustic signal with increased intensity. Recently, a technique to produce UCA from microorganisms was developed and it consists of lysing microorganism cells to obtain gas vesicle (GV) after cultivation in the laboratory. GVs occur almost exclusively in aquatic microorganisms, as Microcystis aeruginosa (MYC), and provide buoyancy which permit to float towards the water surface. This work implemented a technique to produce GVs from MYC, at the Ultrasound Laboratory, and inspected their properties of acting as UCAs, analyzed through ultrasonic images acquired at 40 MHz, and their structural characteristics such as morphology, diameter, and length. Methods: After the cultivation of MYC, the buoyant cells with GVs were separated from the culture medium and submitted to cell lysis with chemical treatment. Thereafter, the solution with lysed cells was centrifuged, at 300g during 8 h at 4–8 °C, to isolate the GVs (absorbance 0.6, λ = 500 nm). Results: Transmission electron microscopy inspection revealed the MYC-GVs with elliptical morphology and having a diameter between 100 and 150 nm and length near to 200 nm. B-mode ultrasound images of the solutions proved the GV’s ability to generate an echo signal, thus confirming their performance as UCAs. © 2020, Sociedade Brasileira de Engenharia Biomedica.

关键词： Cytology

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Structural validation of the “Teacher’s report form” attention problems scale in a Brazilian sample

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Measurement Instruments for the Social Sciences 2021年第1期3卷 1-9页

作者： Pires, Thiago Rocha, Marina Assis, Simone Nobre, Flavio Department of Studies on Violence and Health National School of Public Health (Fiocruz) Rio de Janeiro Brazil Postgraduate Program in Developmental Disorders Universidade Presbiteriana Mackenzie Sao Paulo Brazil Neurology Postgraduate Program University Hospital Gaffrée and Guinle (Unirio) Rio de Janeiro Brazil Biomedical Engineering Program/ COPPE Department Universidade Federal do Rio de Janeiro Rio de Janeiro Brazil

Attention deficit hyperactivity disorder is one of the most common childhood neurodevelopmental syndromes. Although clinical evaluation is considered the gold standard in diagnosing psychiatric disorders, in epidemiological studies, this evaluation is rarely used for practical and financial reasons. Instead, psychometric instruments are used to screen for the disorders. In this case, it is essential to investigate whether these instruments are suitable for measuring the proposed problem. This study aims to verify the structural validation of the Attention Problems Scale of the Teacher’s Report Form (TRF). A random sample of 445 TRF filled out by the teacher of children from São Gonçalo/RJ was selected. The confirmatory factor analysis was applied to validate some factor structures that have been raised in the literature. A second aspect analyzed was the use of structural equation models to verify the validated factorial structure’s relationship with some comorbidities. The bifactor model was the most suitable to explain the TRF child’s Attention Problems Scale’s factor structure. It presented the best-fit quality scores for confirmatory factor analysis than other tested structures. Although it presented good indicators for structural validity, some symptoms could be reassessed to have a more consistent instrument. The bifactor model as an explanatory structure in SEM was able to predict important mental health outcomes. These results are an additional validation to the bifactor model. The results suggest the validity of the TRF’s Attention Problems Scale. The instrument’s factor structure was also appropriate because it corroborated most of the association’s assumptions between subtypes of attention problems and other aspects of mental health. The existence of screening scales adapted to Brazilian Portuguese can substantially impact many children who have difficulty learning. Also, the screening scales can be a useful tool for the health sector to facilitate referra

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

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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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Do FCU and ECU muscle architecture in children with hemiparetic cerebral palsy affect wrist functionality?

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Research on biomedical engineering 2019年第3-4期35卷 173-181页

作者： Barroso, Patricia Neto de Oliveira, Liliam Fernandes Amaral, Giovanna Mendes Gontijo, Ana Paula Bensemann Campos, Márcio Rodrigues Menegaldo, Luciano Luporini Biomedical Engineering Program COPPE Federal University of Rio de Janeiro Av Horácio Macedo Rio de Janeiro2030 Brazil School of Physical Education and Sports Federal University of Rio de Janeiro Rio de Janeiro Brazil Belo Horizonte Brazil Department of Physical Therapy Federal University of Minas Gerais Belo Horizonte Brazil Department of Radiology and Image Diagnosis University Hospital Federal University of Minas Gerais Belo Horizonte Brazil

Purpose: In individuals with cerebral palsy (CP), wrist flexor and extensor muscles can have impaired tonus, strength, posture, and range of motion. Muscle force and movement generating capacity are related to muscle architecture. The purpose of the study was to measure muscle morphology of the flexor (FCU) and extensor carpi ulnaris (ECU) muscles and compare it with strength and passive stiffness in affected and unaffected forearms of children with hemiparetic CP. Methods: Nine children (MACS levels 1 and 2) were analyzed. Ultrasound was used to measure the maximal cross-sectional area, muscle thickness, and muscle perimeter of FCU and ECU. The strength of the wrist flexors and extensors muscles was measured using a manual dynamometer. Wrist flexion passive stiffness was evaluated using isokinetic dynamometry in passive mode. Results: No significant differences in cross-sectional area, anteroposterior distance, and perimeter between unaffected and affected forearm were observed. Flexion and extension isometric torques were reduced in the affected forearm compared with the unaffected, except the passive stiffness, which was increased. A correlation matrix analysis presented some significant correlations between morphological and functional outcomes. Conclusion: Wrist flexion and extension torques are reduced in the affected side of children with hemiparetic CP, and passive stiffness is increased, even without changes in FCU and ECU morphological parameters. © 2019, Sociedade Brasileira de Engenharia Biomedica.

关键词： Muscle

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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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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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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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Construction of mixed covering arrays using a combination of simulated annealing and variable neighborhood search

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Electronic Notes in Discrete Mathematics 2015年 47卷 109-116页

作者： Rodriguez-Cristerna, Arturo Torres-Jimenez, Jose Gómez, W. Pereira, W.C.A. Technology Information Laboratory CINVESTAV Ciudad Victoria Tamaulipas Mexico Biomedical Engineering Program/COPPE Federal University of Rio de Janeiro Rio de Janeiro Brazil

The construction of Mixed Covering Arrays (MCA) with the minimum number of rows has been a problem faced in different ways. This paper aims to construct near optimal MCAs through a novel approach based on Simulated Annealing (SA) and Variable Neighborhood Search (VNS). The solution quality of the proposed algorithm was measured by solving two benchmarks and the obtained results show a significant quality improvement over the results of previously reported metaheuristics. © 2014 Elsevier B.V.

关键词： Mixed covering arrays Simulated annealing Variable neighborhood search

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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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Breast tumor classification in ultrasound images using neural networks with improved generalization methods 37

Breast tumor classification in ultrasound images using neura...

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37th Annual International Conference of the IEEE engineering in Medicine and Biology Society, EMBC 2015

作者： De S. Silva, S.D. Costa, M.G.F. De A. Pereira, W.C. Filho, C. F. F. Costa Amazonas Federal University Manaus AM Brazil Center for Research and Development in Electronic and Information Technology Federal University of Amazonas Technology and Information Center Manaus AM Brazil Biomedical Engineering Program/COPPE Federal University of Rio de Janeiro Rio de Janeiro Brazil Center for Research and Development in Electronic and Information Technology Federal University of Amazonas Manaus AM Brazil

ISBN: (纸本)9781424492718

Mammography, scintimammography and ultrasound images have been used to increase the specificity of breast cancer image diagnosis. Concerning breast cancer image diagnosis with ultrasound, some results found in the literature show better performance of morphological features in breast cancer lesion differentiation and that a reduced set of features shows a better performance than a large set of features. In this study we evaluated the performance of neural network classifiers, with different training stop criteria: mean square error, early stop and regularization. The last two criteria were developed to improve neural network generalization. Different sets of morphological features were used as neural network inputs. Training sets comprised of 22, 8, 7, 6, 5 and 4 features were employed. To select reduced sets of features, a scalar selection technique with correlation was used. The best results obtained for accuracy and area under the ROC curve were 96.98% and 0.98, respectively. The performance obtained with all 22 features is slightly better than the one obtained with a reduced set of features. © 2015 IEEE.

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