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50th Computing in Cardiology, CinC 2023

作者： Winkert, T. Benchimol-Barbosal, P.R. Nadal, J. Coppe Institute Universidade Federal Do Rio de Janeiro Biomedical Engineering Program Rio de Janeiro Brazil Universidade Do Estado Do Rio de Janeiro Hospital Universitário Pedro Ernesto Rio de Janeiro Brazil

ISBN: (纸本)9798350382525

To reduce the incidence of sudden cardiac death (SCD), risk stratification markers have a relevant role. Microvolt T-wave alternans (MTWA) is a marker of SCD risk, defined as T-wave amplitude variation in the ECG. Usually, MTWA tests are carried out in noisy environments when interferences are expected. Baseline drifting correction methods may distort ECG signals, compromising MTWA analysis. This work assesses the impact of baseline drifting removal (BLDR) by two approaches. Signals with controlled baseline drifting, respiratory fluctuations and MTWA were analyzed. The classical BLDR approach (CA) estimates baseline signals using ECG fiducial points. The time-space cancellation approach (TSC) uses only T-wave information to assemble a vector with T-wave amplitudes, calculated by the difference between the maximum T-wave value and its endpoint. The squared coherence between the spectrum from each approach and the spectrum of the ECG without baseline drifting was calculated. At the alternation frequency (0.5 cycles-per-beat) a higher coherence occurred with TSC (0.57) as compared to CA (0.19). Results indicate that CA adds a distortion to the ECG, compromising MTWA. Conversely, the TSC approach preserves MTWA oscillations and has the potential to improve MTWA quantification. © 2023 CinC.

关键词： Electrocardiograms

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Application of ShearWave™ Elastography to evaluate heat-induced changes in the Young’s modulus of fresh bovine muscle: a preliminary study

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Research on biomedical engineering 2021年第2期37卷 157-169页

作者： Costa-Júnior, José Francisco Silva de Oliveira, Viviane Bastos De Matheo, Lucas Lobianco de Albuquerque Pereira, Wagner Coelho Brazilian Air Force Academy PirassunungaSP Brazil Biomedical Engineering Program - COPPE Federal University of Rio de Janeiro Rio de JaneiroRJ Brazil

Purpose: The purpose of this study was to investigate the variation in the Young’s modulus (E) of bovine muscle samples as a function of temperature change generated by therapeutic ultrasound using ShearWave™ Elastography. Methods: Initially, the bovine muscle was heated via therapeutic ultrasound with a frequency of 3 MHz, nominal intensity of 2 W·cm−2, and application time of 2 min. Immediately following cessation of therapeutic irradiation, an E image was recorded and the stiffness was measured in circular area positioned at six depths (from 0.4 to 2.9 cm) in the center of the region of interest. Next, an E image was recorded every minute for the first 5 min. Over the next 30 min, an image was recorded every 5 min. Finally, an image was acquired 60 min after cessation of therapeutic irradiation. In the second test, the same experimental procedure was performed 60 min later with the physiotherapy equipment configured with a 10-min application time. Finally, during the ultrasonic irradiation of a new bovine muscle sample, the physiotherapeutic transducer was applied in a circular motion and with an angular velocity of 3.6 ± 0.3 rad·s−1. Results: In the first test, the bovine muscle E decreased from 212.2 ± 32.8 to 80.1 ± 13.8 kPa at 0.4-cm depth, as the temperature increased from 18.2 to 44.9 °C. This effect was reversed when the temperature decreased. In the second test, denaturation and cell death occurred, so an artifact appeared in the elastographic image and the ShearWave™ Elastography did not capture the E from the depth of 1.9 cm. Conclusion: We confirmed that it is possible to use ShearWave™ Elastography to investigate heat-induced changes in the elastic modulus of biological tissue. © 2021, Sociedade Brasileira de Engenharia Biomedica.

关键词： Cell death

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U-Net and SegNet performances on lesion segmentation of breast ultrasonography images

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Research on biomedical engineering 2021年第2期37卷 171-179页

作者： Vianna, Pedro Farias, Ricardo de Albuquerque Pereira, Wagner Coelho Biomedical Engineering Program COPPE/Federal University of Rio de Janeiro Av. Horácio Macedo 2030 Room H327 Rio de JaneiroRJ Brazil Systems and Computing Engineering Program COPPE/Federal University of Rio de Janeiro Rio de JaneiroRJ Brazil

Purpose: Screening is the predominant strategy for the early detection of breast cancer. However, image analysis depends on the experience of the radiologist, inserting subjective factors in the evaluation of findings. Most biopsies performed on women with suspicious lesions on breast imaging tests show benignity. This medical technique is invasive and consumes time and resources;therefore, there is a demand to reduce these unnecessary procedures. Computer-aided diagnostics has been increasingly used as a second-reader tool lately, decreasing the diagnostic uncertainty of specialists. Based on this fact, the development of such systems is crucial and can be accomplished by the refinement of its steps, i.e., more accurate segmentation and classification. Considering this scenario, the present work describes the implementation of two well-known convolutional neural networks, U-Net and SegNet, for the segmentation of lesions found in breast ultrasonography. Defining which architecture is most appropriate for this task can ultimately help in reducing the number of biopsies performed. Methods: Convolutional neural networks are used in segmentation by classifying each pixel in an image, based on self-trained weights. Using a dataset of 2054 images, obtained in partnership with the National Cancer Institute, we compared the automatic segmentation performed by the networks with a manual segmentation made by a specialist. Results: Among the two proposed architectures, U-Net obtained better results in this task, obtaining a dice coefficient of 86.3%, and took 68.3% less training time than the SegNet, which achieved a dice score of 81.1%. Conclusion: The two networks can segment ultrasound images with useful accuracy depending on their configuration, with U-Net being faster to train and more accurate. © 2021, Sociedade Brasileira de Engenharia Biomedica.

关键词： Semantic Segmentation

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In Vitro Degradation of Polydioxanone (PDO) Lifting Threads in Microfocused Ultrasound

In Vitro Degradation of Polydioxanone (PDO) Lifting Threads ...

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Pan American Health Care Exchanges, PAHCE

作者： M. H. R. Silva A. Raybolt W. C. A. Pereira Biomedical Engineering Program - COPPE Federal University of Rio de Janeiro RJ Brazil School of Dentistry Federal University of Rio de Janeiro RJ Brazil

ISBN: (数字)9798350390490

ISBN: (纸本)9798350390506

Objective: Analyze the static degradation time of polydioxanone (PDO) threads with or without the association of microfocused ultrasound, which are techniques for aesthetic purposes. Materials and Methods: In vitro assays were conducted in isotonic solution using smooth polydioxanone (PDO) threads divided into 2 groups (n=3): FPL (Smooth Polydioxanone Thread) and FPLU (Smooth Polydioxanone Thread with Ultrasound). The FPLU group underwent microfocused ultrasound. Both groups endured the following analyses: UV spectroscopy Absorbance and Scanning Electron Microscopy (SEM). Results: Absorbance by UV spectroscopy: The concentration levels of molecules in the aliquots showed that at 8 days both FPL and FPLU groups exhibited absorbance levels of 0.0040 (mol −1 /*** −1 ) and 0.00585 (mol −1 /*** −1 ), respectively. At 30 days, these levels were 0.0799 (mol −1 /*** −1 ) and 0.0543 (mol −1 /*** −1 ). At 60 days, the FPLU group showed significant increase to 0.2039 (mol −1 /*** −1 ) compared to the FPL group at 0.1152 (mol −1 /*** −1 ) reaching a degradation peaks at 60 days. At 90 days, the FPL group presented 0.1299 (mol −1 /*** −1 ) and the FPLU group presented 0.2377 (mol −1 /*** −1 ). SEM: Morphological differences were observed in both groups. Conclusion: FPLU group showed higher absorbance over time. Microfocused ultrasound accelerated degradation time PDO threads, diminishing its functionality.

关键词： Degradation Scanning electron microscopy Spectroscopy In vivo Ultrasonic imaging In vitro Physics

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Ultrasonography Validation of Condylar and Pre-Condylar Distances and its Correlation with the Arthralgia Intensity Attributed to Local Arthritis

Ultrasonography Validation of Condylar and Pre-Condylar Dist...

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Pan American Health Care Exchanges, PAHCE

作者： C. El-Sayed G. S. Goffredo Filho L. Sad R. S. Tesch W. C. A. Pereira Biomedical Engineering Program COPPE/Federal University of Rio de Janeiro Rio de Janeiro RJ Brazil TMD and Orofacial Pain Department Petrópolis Medical School Petrópolis RJ Brazil

ISBN: (数字)9798350390490

ISBN: (纸本)9798350390506

Temporomandibular disorders (TMD) represent a prevalent form of musculoskeletal pain observed in individuals with chronic pain. Timely and accurate diagnosis is essential for effective therapeutic interventions, with imaging examinations playing a crucial role in assessing articular structures, as outlined by the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Given the significance of temporomandibular joint (TMJ) evaluation in dentistry, the integration of ultrasonography (USG) into clinical practice facilitates early detection of joint pathologies. This study aims to evaluate the correlation between condylar and pre-condylar measures to determine which more accurately reflects capsular expansion associated with intra-articular effusion and the intensity of arthralgia reported by patients in the future. Measurements of condylar and pre-condylar distances were conducted in a cohort of volunteers. The Spearman correlation coefficient between condylar and pre-condylar distances was determined to be 0.36. The results suggest a statistically moderate correlation between condylar and pre-condylar measures, indicating that the latter may serve as a potentially less biased and more valid screening tool for identifying capsular expansions attributed to intra-articular inflammation and associated pain in patients with TMD.

关键词： Pathology Musculoskeletal system Correlation Pain Ultrasonic variables measurement Ultrasonography Medical services

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Reducing electrocardiographic interference in the multichannel electromyogram to help muscle fatigue assessment in low-intensity contractions

Franklin Open

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Franklin Open 2024年 9卷

作者： Costa Junior, José Dilermando de Seixas, José Manoel Ferreira Leite Miranda de Sá, Antonio Mauricio Federal University of Rio de Janeiro / Biomedical Engineering Program Rio de Janeiro Brazil Federal University of Rio de Janeiro / Signal Processing Laboratory COPPE/Poli Rio de Janeiro Brazil

Surface electromyography (EMG) can be used in the rehabilitation of musculoskeletal disorders, for evaluating the coordination of muscles that stabilize a joint, or as an objective tool in assessing muscle fatigue. This latter may be achieved by evaluating the low-frequency content of the EMG. However, the electrocardiogram (ECG) interference is also recorded when EMG is acquired close to the heart. It may mask or even modify the information of interest in the EMG. Different signal processing techniques have been proposed to eliminate ECG artifacts from the EMG signals, the high-pass filter being the most used one. Nevertheless, this classic filtering approach would also attenuate EMG activities below 30 Hz, which contain information from low-intensity muscle contractions. This work addresses the automatic ECG attenuation when multichannel EMG is collected on the left pectoralis major muscle during a muscle fatigue test. The proposed ECG artifact mitigation extends a successful automatic template subtraction (TS) approach, which does not require an extra reference channel and is now applied to independent EMG source signal components extracted using a blind source separation technique (ICA, Independent Component Analysis). The automatic detection of ECG components was performed through two alternative measures: entropy and Kullback-Leibler divergence. While the ECG interference seems to hamper the detection of muscle fatigue in the low-contraction regime, the association ICA+TS preserved better the EMG low-frequency content, and the entropy-based automatic detection was found to be more suitable, avoiding possible errors that might arise from manual detection procedures. © 2024 The Author(s)

关键词： ECG interference mitigation EMG denoising High-pass filter Independent component analysis Multichannel analysis Template subtraction

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Performance of the SegNet in the Segmentation of Breast Ultrasound Lesions

Performance of the SegNet in the Segmentation of Breast Ultr...

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Pan American Health Care Exchanges, PAHCE

作者： P. O. Vianna R. Farias W. C. A. Pereira Biomedical Engineering Program COPPE/Federal University of Rio de Janeiro RJ Brazil Systems and Computing Engineering Program COPPE/Federal University of Rio de Janeiro RJ Brazil

ISBN: (纸本)9781728170558

This work presents a performance analysis of a convolutional neural network (CNN), named SegNet, applied for automatic segmentation of breast ultrasound images. Defining the viability of CNN's could help with feature extraction and posterior classification of lesions, causing a decrease in the number of unnecessary biopsies. The breast ultrasound (BUS) dataset consists of 2054 images from 659 female patients, and each image was manually segmented by an experienced radiologist. The dataset is fed into the CNN without any filtering process applied to it and the test output is then compared with the radiologist's labels. We compared the results of different loss and activation functions, and the experiments reveal that the best performance was achieved using dice loss function, with dice coefficient of 81.1%.

关键词： Image segmentation Ultrasonic imaging Medical services Breast Feature extraction Generative adversarial networks Performance analysis

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Baseline Drifting Correction for Automated MTWA Measurements

Baseline Drifting Correction for Automated MTWA Measurements

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Computers in Cardiology (CinC)

作者： T Winkert P R Benchimol-Barbosal J Nadal Biomedical Engineering Program COPPE Institute Universidade Federal do Rio de Janeiro Rio de Janeiro Brazil Hospital Universitário Pedro Ernesto Universidade do Estado do Rio de Janeiro Rio de Janeiro Brazil

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Evaluation of materials for confection of phantoms to mimetize acoustic properties of tendons

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Research on biomedical engineering 2021年第1期37卷 47-52页

作者： Gomes, Gabriela Beatriz De Matheo, Lucas Lobianco da Silva, Flavia Fernandes Ferreira Maggi, Luis Eduardo von Krüger, Marco Antônio de Albuquerque Pereira, Wagner Coelho Programa de Engenharia Biomédica COPPE Universidade Federal do Rio de Janeiro Rio de JaneiroRJ Brazil Biomedical Engineering Program COPPE Federal University of Rio de Janeiro Rio de JaneiroRJ Brazil Programa de Pós-Graduação em Ciências da Saúde na Amazônia Ocidental Universidade Federal do Acre Rio BrancoAC Brazil Graduate Program in Health Sciences in the Western Amazon Federal University of Acre Rio BrancoAC Brazil

Background: The tendon is a structure found in different parts of the human body. Damages within tendons cause movement deficit and discomfort, which requires medical and therapeutic treatment. One useful tool is the therapeutic ultrasound;however, fine adjustment is required to avoid further lesions to the patient. Aiming at enhancing the resources for the research in the study of therapeutic ultrasound and the knowledge regarding its application to tendons, the objective of this work is to evaluate materials to prepare ultrasonic phantoms that mimic the acoustic properties of the tendons. Materials and methods: The acoustic characterization of a pig tendon and three PVCP-based phantoms were made. The transmission-reception method was used, and the propagation speed and attenuation of each phantom were calculated. Results: The tendon showed an attenuation of 4.8 ± 1.7 dB cm−1 and propagation speed of 1497.5 ± 21.6 m s−1. The attenuation of the phantoms varied from 1.3 ± 1.2 to 4.0 ± 1.0 dB cm−1 and velocity from 1509.9 ± 31.8 to 1519.8 ± 26.7 m s−1. Conclusions: We concluded that among the materials used, it was possible to find values statistically similar to this animal tendon in the PVCP phantom with 15% glycerin and 10% PVC powder. Complementary studies with other materials and protocols are needed to mimic other values found in the literature. © 2020, Sociedade Brasileira de Engenharia Biomedica.

关键词： Ultrasonics

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Artificial Visual Phantoms for Ultrasound Thermal Therapy

Artificial Visual Phantoms for Ultrasound Thermal Therapy

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Ultrasonics Symposium (LAUS), IEEE UFFC Latin America

作者： Natalia Garay Badenian Edgar Taka Nicolas Benech Guillermo Cortela Franco Simini Núcleo de Ingeniería Biomédica Universidad de la República l Montevideo Uruguay Biomedical Engineering Program-COPPE Universidad de Rio de Janeiro Rio de Janeiro Brazil Laboratorio de Acústuca Ultrasonora Facultad de Ciencias Universidad de la República Montevideo Uruguay

ISBN: (数字)9798350349085

ISBN: (纸本)9798350349092

This work is part of a project to develop a device for ultrasound energy delivery to inhibit or ablate epileptic foci in the brain. Phantoms simulating brain tissue were created using agar, egg whites, and water. They were irradiated with ultrasound energy at 250, 275, and 300 mV for 25 to 40 seconds. Temperature changes were monitored with thermocouples. Results showed visible color changes in phantoms at 275 and 300 mV, reaching temperatures of up to 74 °C at 300 mV (23 Ws). This provides a consistent method for phantom production and a visual indication of energy dissipation levels. Further research will establish clinical parameters for using focused ultrasound in epilepsy treatment.

关键词： Temperature measurement Visualization Brain Ultrasonic imaging Transmitters Phantoms Epilepsy

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