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International Technical Conference o Circuits/Systems, Computers and Communications (ITC-CSCC)

作者： Tanawan Tearwattanarattikal Apiwat Lek-uthai Interdisciplinary Programme of Biomedical Engineering Chulalongkorn University Bangkok Thailand Department of Electrical Engineering Chulalongkorn University Bangkok Thailand

Vectorcardiography (VCG) is an alternative method of electrocardiography which provides useful spatial information for the cardiologists to diagnose and localise cardio-vascular diseases with higher accuracy. However, the method of measuring the VCG requires a different lead system which makes the monitoring devices more complicated. Thus, the method of reconstructing VCG from standard 12-lead ECG, which is more ubiquitous, was developed in past years. In this paper, we proposed a novel method of reconstructing VCG from standard 12-lead ECG by using convolutional neural network (CNN) which adds temporal information to the training process. The result indicates that adding convolutional layer before feeding into fully-connected MLP layers improves the performance of model significantly from the conventional methods.

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High-precision Rhythm-based Detection of Atrial Fibrillation and Frequent Premature Contractions using Extreme Gradient Boosting

High-precision Rhythm-based Detection of Atrial Fibrillation...

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biomedical engineering International Conference (BMEiCON)

Atrial fibrillation and premature contractions are two of the most common types of arrhythmia, potentially leading to serious medical complications, such as stroke and heart failure. Normally, these two arrhythmias are detected by inspecting the electrocardiogram (ECG) which requires medical expertise, making it unsuitable for home-based monitoring used by patients with no medical background. This research aimed to develop a rhythm-based algorithm to detect atrial fibrillation and frequent premature contractions with at least 20% burden. The algorithm was trained using ECG data from publicly available MIT-BIH Arrhythmia Database and Long-Term AF Database divided into 30-second-long ECG segments. After QRS detection, relevant features, involving heart rate variability, Shannon’s entropy, and sample entropy, were extracted from the RR interval and classified using state-of-the-art extreme gradient boosting (XGBoost). The final model achieved the performance of 98.10% F 1 -score on an independent test set. Thus, this algorithm can be applied on home-based monitoring which can be used as a screening intervention for the healthcare system.

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Constrained CycleGAN for Effective Generation of Ultrasound Sector Images of Improved Spatial Resolution

arXiv

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arXiv 2023年

作者： Sun, Xiaofei Li, He Lee, Wei-Ning Department of Electrical and Electronic Engineering The University of Hong Kong Hong Kong Biomedical Engineering Programme The University of Hong Kong Hong Kong

Objective. A phased or a curvilinear array produces ultrasound (US) images with a sector field of view (FOV), which inherently exhibits spatially-varying image resolution with inferior quality in the far zone and towards the two sides azimuthally. Sector US images with improved spatial resolutions are favorable for accurate quantitative analysis of large and dynamic organs, such as the heart. Therefore, this study aims to translate US images with spatially-varying resolution to ones with less spatially-varying resolution. CycleGAN has been a prominent choice for unpaired medical image translation;however, it neither guarantees structural consistency nor preserves backscattering patterns between input and generated images for unpaired US images. Approach. To circumvent this limitation, we propose a constrained CycleGAN (CCycleGAN), which directly performs US image generation with unpaired images acquired by different ultrasound array probes. In addition to conventional adversarial and cycle-consistency losses of CycleGAN, CCycleGAN introduces an identical loss and a correlation coefficient loss based on intrinsic US backscattered signal properties to constrain structural consistency and backscattering patterns, respectively. Instead of post-processed B-mode images, CCycleGAN uses envelope data directly obtained from beamformed radio-frequency signals without any other non-linear postprocessing. Main Results. In vitro phantom results demonstrate that CCycleGAN successfully generates images with improved spatial resolution as well as higher peak signal-to-noise ratio (PSNR) and structural similarity (SSIM) compared with benchmarks. Significance. CCycleGAN-generated US images of the in vivo human beating heart further facilitate higher quality heart wall motion estimation than benchmarks-generated ones, particularly in deep regions. The codes are available at https://***/xfsun99/CCycleGAN-TF2. Copyright © 2023, The Authors. All rights reserved.

关键词： Backscattering

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Automated Microbubble Discrimination in Ultrasound Localization Microscopy by Vision Transformer

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IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 2025年 PP卷 PP页

作者： Wang, Renxian Lee, Wei-Ning The University of Hong Kong Department of Electrical and Electronic Engineering Hong Kong The University of Hong Kong Department of Electrical and Electronic Engineering Biomedical Engineering Programme Hong Kong

Ultrasound localization microscopy (ULM) has revolutionized microvascular imaging by breaking the acoustic diffraction limit. However, different ULM workflows depend heavily on distinct prior knowledge, such as the impulse response and empirical selection of parameters (e.g., the number of microbubbles (MBs) per frame M), or the consistency of training-test dataset in deep learning (DL)-based studies. We hereby propose a general ULM pipeline that reduces priors. Our approach leverages a DL model that simultaneously distills microbubble signals and reduces speckle from every frame without estimating the impulse response and M. Our method features an efficient channel attention vision transformer (ViT) and a progressive learning strategy, enabling it to learn global information through training on progressively increasing patch sizes. Ample synthetic data were generated using the k-Wave toolbox to simulate various MB patterns, thus overcoming the deficiency of labeled data. The ViT output was further processed by a standard radial symmetry method for sub-pixel localization. Our method performed well on model-unseen public datasets: one in silico dataset with ground truth and four in vivo datasets of mouse tumor, rat brain, rat brain bolus, and rat kidney. Our pipeline outperformed conventional ULM, achieving higher positive predictive values (precision in DL, 0.88-0.41 vs. 0.83-0.16) and improved accuracy (root-mean-square errors: 0.25-0.14 λ vs. 0.31-0.13 λ) across a range of signal-to-noise ratios from 60 dB to 10 dB. Our model could detect more vessels in diverse in vivo datasets while achieving comparable resolutions to the standard method. The proposed ViT-based model, seamlessly integrated with state-of-the-art downstream ULM steps, improved the overall ULM performance with no priors. © 1986-2012 IEEE.

关键词： Optical transfer function

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A Low-Complexity and Efficient VR-Based System with Infrared Image Processing for Assessing the Angle of Ocular Misalignment in Strabismus Patients

A Low-Complexity and Efficient VR-Based System with Infrared...

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International Conference on Electrical engineering/Electronics, Computer, Telecommunications and Information Technology, ECTI-CON

作者： Salisa Buapong Worawalun Honglertnapakul Rath Itthipanichpong Pakpum Somboon Interdisciplinary Programme of Biomedical Engineering Chulalongkorn University Bangkok Thailand Department of Ophthalmology Chulalongkorn University and King Chulalongkorn Memorial Hospital Bangkok Thailand

ISBN: (数字)9798350381559

ISBN: (纸本)9798350381566

Strabismus , an ophthalmic condition affecting approximately 2% to 5% of the global population and with a pediatric prevalence rate of about 2% to 4%, can lead to binocular vision impairment and eventual vision loss if left uncorrected for an extended period. Early detection and correction of ocular deviations are crucial in mitigating these risks. However, primary clinical tests like the prism cover test (PCT) and the Hirschberg test (HT) have limitations. These tests rely on operator skills for an accurate measurement. Moreover, the PCT demands sustained patient focus throughout prolonged testing. In our study, we developed a simplified and efficient VR-based system with infrared image processing to evaluate the angle of ocular deviation in strabismus patients. This system utilizes an automated assessment method to effectively imitate the alternate cover test, a traditional procedure for strabismus assessment. The results showed no significant differences in measurements of ocular misalignment between our VR-based system and the doctor's test among the strabismus patients. Consequently, this system prototype offers noninvasive assessment, rapid detection, and ease of operation, making it a potentially efficient alternative for the clinical screening of strabismus.

关键词： Accuracy Image processing Visual impairment Sociology Medical services Telecommunications Statistics

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Design and Control of the Portable Upper-limb Elbow-forearm Exoskeleton for ADL Assistance

Design and Control of the Portable Upper-limb Elbow-forearm ...

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IEEE/ASME (AIM) International Conference on Advanced Intelligent Mechatronics

作者： Hilary HY Cheng Thomas M. Kwok Haoyong Yu Department of Biomedical Engineering National University of Singapore Singapore Integrative Sciences and Engineering Programme NUS Graduate School National University of Singapore Singapore

This paper proposes a portable Unilateral Elbow- Forearm Exoskeleton (UEFE) for assisting chronic stroke patients in the activities of daily living (ADL). UEFE provides users 2DoFs assistance: elbow flexion/extension (eF/E) and forearm pronation/supination (eR). Other than eF/E, forearm rotation is equally crucial for completing ADL tasks; however, limited exoskeletons provide eR assistance for users in ADL. Even though some existing exoskeletons are equipped with eR joints, those devices are not practical to use in ADL due to their heavy weight, insufficient assistance, and obstructing handles. In UEFE, both active joints are actuated by Series Elastic Actuators (SEA) through Bowden cables to ensure safe interactions and a lightweight solution. The design of UEFE is based on the ADL requirements, which include the range of motion (ROM) and torque. The handle-free feature also allows users to pick up objects in ADL. A pill-taking task with impedance control demonstrates the feasibility of using the UEFE in ADL assistance.

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A 2-DoF Elbow Exoskeleton with Spherical Scissor Mechanism for ADL Assistance

A 2-DoF Elbow Exoskeleton with Spherical Scissor Mechanism f...

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IEEE International Conference on Robotics and Biomimetics

作者： Thomas M. Kwok Hilary HY Cheng Haoyong Yu NUS Graduate School for Integrative Sciences and Engineering Programme National University of Singapore Singapore Department of Biomedical Engineering National University of Singapore Singapore

This paper presents the design and experimental validation of a 2-DoF elbow exoskeleton with a 2-DoF spherical scissor mechanism (SSME) to assist chronic stroke patients with upper limb impairments in activity-of-daily-living (ADL) tasks. Since forearm pronation/supination was missing in most portable exoskeletons and the existing designs with forearm rotation were too bulky, we propose a 2-DoF elbow exoskeleton with a spherical mechanism for elbow and forearm assistance. Benefiting from the spherical scissor and cable-driven mechanisms, the SSME can assist in elbow flexion/extension and forearm pronation/supination, up to 97.467% ADL workspace, with a mechanical design as light as 0.543 kg, practical for daily use. Besides, the proposed sensing method and kinematic model for the spherical scissor mechanism can measure human joint motions, solving the sensing challenge for forearm motion in most existing upper limb exoskeletons. Furthermore, with inverse kinematics and robot-joint-space impedance control, the SSME can independently control the elbow and forearm angle with minimal influence on another, regardless of its coupled nature. Moreover, our experiments have validated the proposed exoskeleton design in terms of the force control performance of actuators, robot joint impedance control response, and robot assistance in an ADL task.

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Segmentation of Tumour Regions for Tubule Formation Assessment on Breast Cancer Histopathology Images 11th

Segmentation of Tumour Regions for Tubule Formation Assessme...

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11th International Conference on Robotics, Vision, Signal Processing and Power Applications, RoViSP 2021

作者： Jing, Tan Yee Mustafa, Nazahah Yazid, Haniza Rahman, Khairul Shakir Ab Biomedical Electronic Engineering Programme Faculty of Electronic Engineering Technology Universiti Malaysia Perlis Kampus Alam UniMAP Pauh Putra Arau Perlis02600 Malaysia Department of Pathology Hospital Tuanku Fauziah Kangar Perlis01000 Malaysia

ISBN: (纸本)9789811681288

Breast cancer is the second leading cause of cancer death in women worldwide. In Malaysia, one out of 20 women will develop breast cancer once in their lifetime. Nottingham Histological Grading (NHG) system is widely accepted worldwide as the gold standard in providing the overall grade to breast cancer. Tubule formation is an important breast cancer feature used in the NHG system. Assessment of tubule formation requires pathologist to identify tumour regions. However, colour variation on breast histopathology images could provide nonstandard imaging and influence tumour regions detection. Manual identification of tumour regions using microscope may also vary between pathologists. Thus, automatic segmentation is crucial to detect tumour regions. By eliminating the irrelevant regions on breast histopathology images using automatic segmentation method, pathologist can focus on the tumour regions for further investigation. This study proposed a simple segmentation using global thresholding method to segment tumour regions on breast histopathology images. Partial contrast stretching and median filter were applied as pre-processing to provide better image quality for further segmentation processing. Post-processing using morphological operation and boundary padding were applied to enhance the segmentation results. The proposed method was able to segment the tumour regions on breast histopathology images and obtained accuracy, sensitivity and specificity of 84.22%, 85.83% and 84.89% respectively. © 2022, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Tumors

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A Reliable Kinematic Measurement of Upper Limb Exoskeleton for VR Therapy with Visual-inertial Sensors

A Reliable Kinematic Measurement of Upper Limb Exoskeleton f...

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IEEE/ASME (AIM) International Conference on Advanced Intelligent Mechatronics

作者： Thomas M. Kwok Tong Li Haoyong Yu Integrative Sciences and Engineering Programme NUS Graduate School National University of Singapore Singapore Dept. of Biomedical Engineering National University of Singapore Singapore

Virtual reality (VR) is a powerful technology that provides a structured and safe environment for ADL training, allowing patients to have a similar experience as real-world training. However, a limited robot sensing system is proven reliable for such training. The effectiveness of current robot sensors was limited due to inherent technical problems, such as the installation challenges of encoders and IMU’s drifting, acceleration, and magnetic issues. Thus, we propose a novel and reliable sensing system consisting of absolute rotary encoders and visual-inertial sensors for the upper-limb exoskeleton in VR therapy. Our sensing system has demonstrated angle measurement for various robot joint types, including hinge, ball, and revolute joints along the limb’s longitudinal axis. Its sensing feedback can construct virtual arms that interact with virtual objects in the VR environment. In our experiments, with Vicon as the ground truth, our visual-inertial sensors achieved root-mean-square errors smaller than 2.3491° and a strong correlation (r ≥ 0. 9640, p < 0. 001). Additionally, the experiment result of seven healthy subjects indicated that subjects had similar muscle activations, joint ROM, and joint trajectories in the VR task with our sensing system, compared with the real-world task. Thus, our proposed sensing system can potentially be used in the upper-limb exoskeleton for VR therapy.

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Automatic Platform for Upper Extremity Musculoskeletal Disorder Risks Estimation from Repetitive Actions -Preliminary results.

Automatic Platform for Upper Extremity Musculoskeletal Disor...

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2023 IEEE International Symposium on Medical Measurements and Applications, MeMeA 2023

作者： Aqueveque, Pablo Gutierrez, Manuel Pena, Guisella Germany, Enrique Gomez, Britam Retamal, Gustavo Ortega-Bastidas, Paulina Universidad de Concepción Faculty of Engineering Electrical Engineering Department Concepción Chile Universidad de Concepción Faculty of Biological Sciences Ergonomics Department Concepción Chile Universidad de Santiago de Chile Biomedical Engineering Faculty of Engineering Santiago Chile Universidad de Concepción Faculty of Medicine Kinesiology Department Concepción Chile Universidad Rey Juan Carlos Health Sciences PhD Programme Madrid Spain

ISBN: (纸本)9781665493840

Work-related musculoskeletal disorders is a major problem for worker's health when dealing with repetitive tasks. The Occupational Repetitive Actions Index (OCRA) is one of the most widely used methods for determining upper extremity risk from repetitive actions. Traditional risk assessment consists in observing and recording the entire workday or part of it. This observational assessment depends on the evaluator's expertise, which lead to inter-evaluator variability in the results even for the same job. This paper presents preliminary results of a platform that combines motion capture data with a digitalized OCRA Index method to classify risks under repetitive tasks conditions. Repetitive action tasks were performed in a controlled laboratory environment on ten healthy subjects, where optical and inertial sensors were used to capture movement. Body segment positions, displacements and joint angles were fed into the platform comparing their processing time and reliability. Although results indicate that optical systems have a better performance than inertial sensors for posture evaluation, the last has better practical applicability since optical markers occlusion in the working setup induced measurement errors. In addition, inertial systems are more likely to be used on in real working scenarios due to their ease of use and portability. Finally, inertial sensors combined with the digitized OCRA index method platform effectively reduces 67% of the needed evaluation time compared to traditional observational methods. © 2023 IEEE.

关键词： Risk assessment

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