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Directional Coherence Factor for Volumetric Ultrasound Imaging with Matrix Arrays

IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control 2025年第6期72卷 817-827页

作者： Wu, Xiaochuan 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 and Biomedical Engineering Programme Hong Kong

Matrix arrays with small apertures limit spatial and contrast resolutions of volumetric ultrasound imaging. Coherence-based beamformers are prevalent for side lobe suppression and resolution improvement. While the spatial coherence of a matrix array is fundamentally a 2D function, conventional coherence factor (CF) methods neglect the directional variation of an M × N matrix array when calculating volumetric coherence. We hereby propose a projectionbased directional coherence factor (DCF) to exploit the 2D nature of volumetric coherence function. Instead of computing the coherent and incoherent summations across the entire 2D aperture, DCF projects aperture data onto azimuthal, elevational, diagonal, and antidiagonal directions and subsequently calculates the coherence factors for each direction separately. The orthogonal coherence pairs, i.e., azimuth and elevation, diagonal and anti-diagonal, are multiplied to obtain DCFRC and DCFDiag, respectively. The Jaccard similarity of the DCFRC and DCFDiag is used to derive the final DCF to weigh the reconstructed images. We evaluated the performance of DCF beamforming in point-target simulations, multi-purpose phantom experiments, and in vivo muscle imaging, and compared it to delay-and-sum (DAS) and CF beamformers. Our DCF achieved side lobe reduction throughout the entire volume compared to conventional CF. Moreover, diagonal weighting significantly improved, on average, the azimuthal resolution by 41.3% vs. DAS and 7.35% vs. CF as well as the elevational resolution by 40.4% vs. DAS and 38.7% vs. CF. Our proposed DCF offers a practical solution for resolution and contrast enhancement of volumetric imaging in 2D matrix array configurations. © 1986-2012 IEEE.

关键词： Ultrasonic imaging

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engineering human immune organoids for translational immunology

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Bioactive Materials 2025年第2期44卷 164-183页

作者： Intan Rosalina Suhito Christina Sunil Andy Tay Department of Biomedical Engineering National University of Singapore117583Singapore Institute of Health Innovation&Technology National University of Singapore117599Singapore Tissue Engineering Programme National University of Singapore117510Singapore

Animal models have been extensively used as a gold standard in various biological research,including immu-nological *** high availability and ease of handling procedure,they inadequately represent complex interactions and unique cellular properties in humans due to inter-species genetic and microenvironmental differences which have resulted in clinical-stage *** technology has gained enormous attention as they provide sophisticated insights about tissue architecture and functionality in miniaturized *** this review,we describe the use of organoid system to overcome limitations in animal-based investigations,such as physiological mismatch with humans,costly,time-consuming,and low throughput *** organoids are one of the specific advancements in organogenesis ex vivo,which can reflect human adaptive immunity with more physiologically relevant *** discuss how immune organoids are established from patient-derived lymphoid tissues,as well as their characteristics and functional features to understand immune mechanisms and ***,some bioengineering perspectives are considered for any potential progress of immuno-engineered organoids.

关键词： Lymphoid organ Organoids Human adaptive immune system In vitro immune model

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High-precision Rhythm-based Detection of Atrial Fibrillation and Frequent Premature Contractions using Extreme Gradient Boosting 15

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

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15th biomedical engineering International Conference, BMEiCON 2023

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

ISBN: (纸本)9798350345247

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% F1-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. © 2023 IEEE.

关键词： Electrocardiograms

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Vectorcardiographic Reconstruction from Standard 12-Lead Electrocardiogram Using Convolutional Neural Network

Vectorcardiographic Reconstruction from Standard 12-Lead Ele...

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2023 International Technical Conference on Circuits/Systems, Computers, and Communications, ITC-CSCC 2023

ISBN: (纸本)9798350326413

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. © 2023 IEEE.

关键词： Electrocardiograms

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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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2023 IEEE International Conference on Robotics and Biomimetics, ROBIO 2023

作者： Kwok, Thomas M. Cheng, Hilary H.Y. Yu, Haoyong National University of Singapore Nus Graduate School for Integrative Sciences and Engineering Programme 117575 Singapore National University of Singapore Department of Biomedical Engineering 117575 Singapore

ISBN: (纸本)9798350325706

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. © 2023 IEEE.

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Protein-nucleic acid hybrid nanostructures for molecular diagnostic applications

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Nano Research 2024年第10期17卷 9003-9014页

作者： Noah R.Sundah Yuxuan Seah Auginia Natalia Xiaoyan Chen Panida Cen Yu Liu Huilin Shao Institute for Health Innovation and Technology National University of SingaporeSingapore 117599Singapore Department of Biomedical Engineering College of Design and EngineeringNational University of SingaporeSingapore 117583Singapore Integrative Sciences and Engineering Programme NUS Graduate SchoolNational University of SingaporeSingapore 119077Singapore Institute of Molecular and Cell Biology Agency for ScienceTechnology and ResearchSingapore 138673Singapore Department of Surgery Yong Loo Lin School of MedicineNational University of SingaporeSingapore 117597Singapore

Molecular diagnostic technologies empower new clinical opportunities in precision ***,existing approaches face limitations with respect to performance,operation and *** molecules including proteins and nucleic acids are being increasingly adopted as tools in the development of new molecular diagnostic *** particular,leveraging their complementary properties—the functional diversity of proteins and the precision programmability of nucleic acids—a wide range of protein–nucleic acid hybrid nanostructures have been *** hybrid structures take diverse forms,ranging from one-dimensional to three-dimensional hybrids,as static assemblies to dynamic machines,and possess myriad functions to recognize target biomarkers,encode vast information and execute catalytic *** by recent advances in this area of molecular nanotechnology,we review the state-of-art design and application of various types of protein–nucleic acid hybrid nanostructures for molecular diagnostics,and present an outlook on the challenges and opportunities for emerging pre-clinical and clinical applications,highlighting the promise for earlier detection,more refined diagnosis and highly tailored treatment decision that ultimately lead to improved patient outcomes.

关键词： molecular nanotechnology DNA-protein hybrid molecular diagnostics precision medicine

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Towards non-invasive biomarkers in colorectal cancer management: A study on integrating radiomics and deep learning-based image processing for tumor-stroma interaction 24

Towards non-invasive biomarkers in colorectal cancer managem...

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8th International Conference on Medical and Health Informatics, ICMHI 2024

作者： Adjei, Prince Ebenezer Otoo, Obed Kojo Yang, Jinlin Rao, Nini Department of Biomedical Engineering School of Life Science and Technology University of Electronic Science and Technology of China Chengdu China Biomedical Engineering Programme Kwame Nkrumah University of Science and Technology Ghana Digestive Endoscopic Center of West China Hospital Sichuan University China Department of Radiology Komfo Anokye Teaching Hospital Kumasi Ghana

ISBN: (纸本)9798400716874

Colorectal cancer (CRC) management, particularly for invasive histopathology analysis, has benefited from the prognostic insights the tumor-stroma ratio (TSR) provides. Despite advances in colonography, histopathology, and radiomics, the relationship between TSR and radiomic features still needs to be studied, given the potential non-invasive nature of radiomics biomarkers. This study explores the relationship between TSR and radiomics that can reduce the reliance on invasive biopsies in CRC management by identifying noninvasive radiomic-based markers. A retrospective analysis was conducted on radiology slides and corresponding histopathology slides from the colorectal cancer patients (n = 15) sourced from The Cancer Genomic Atlas (TCGA). A specialist radiologist manually segmented the tumors, and radiomic feature extraction was performed on radiology slides. A pre-trained vision transformer model characterized pathology slides. Using a tile-based approach, each tile was classified into one of nine distinct classes, resulting in a complete characterization of the entire slide. TSR was estimated as the stroma ratio to tumor area on pathology slides. Statistical correlation analysis and machine learning algorithms were employed to find associations between TSR and radiomic features, including feature importance assessment. Our findings indicate a significant correlation between specific gray-level measurement features and TSR, suggesting the potential of these radiomic features as noninvasive prognostic indicators. In summary, the interaction between radiomics and tumor-stroma ratio (TSR) presents potential opportunities for improving colorectal cancer (CRC) prognosis, treatment decision-making, and patient stratification. © 2024 ACM.

关键词： Noninvasive medical procedures

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Enhancing single-cell encapsulation in droplet microfluidics with fine-tunable on-chip sample enrichment

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Microsystems & Nanoengineering 2024年第1期10卷 149-160页

作者： Tao Tang Hao Zhao Shaofei Shen Like Yang Chwee Teck Lim Department of Biomedical Engineering National University of Singapore117583 SingaporeSingapore Integrative Sciences and Engineering Programme NUS Graduate SchoolNational University of Singapore119077 SingaporeSingapore Shanxi Key Lab for Modernization of TCVM College of Life ScienceShanxi Agricultural UniversityTaiguShanxi 030801China Institute for Health Innovation&Technology National University of Singapore117599 SingaporeSingapore Mechanobiology Institute National University of Singapore117411 SingaporeSingapore Institute for Digital Molecular Analytics and Science Nanyang Technological University636921 SingaporeSingapore

Single-cell encapsulation in droplet microfluidics is commonly hindered by the tradeoff between cell suspension density and on-chip focusing *** this study,we introduce a novel droplet microfluidic chip to overcome this *** chip comprises a double spiral focusing unit,a flow resistance-based sample enrichment module with fine-tunable outlets,and a crossflow droplet generation *** a low-density cell/bead suspension(2×10^(6) objects/mL),cells/beads are focused into a near-equidistant linear arrangement within the double spiral *** excess water phase is diverted while cells/beads remain focused and sequentially encapsulated in individual *** performance was assessed through numerical simulations and experiments at three flow rates(40,60,80μL/min),demonstrating successful focusing at 40 and 80μL/min for beads and cells,*** addition,both simulation and experimental results revealed that the flow resistance at the sample enrichment module is adjustable by punching different outlets,allowing over 50%of the aqueous phase to be ***8n-based droplet detection algorithms realized the counting of cells/beads in droplets,statistically demonstrating single-cell and bead encapsulation rates of 72.2%and 79.2%,*** the results indicate that this on-chip sample enrichment approach can be further developed and employed as a critical component in single-cell encapsulation in water-in-oil droplets.

关键词： beads outlet sample

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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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Digitally-defined ultrathin transparent wireless sensor network for room-scale imperceptible ambient intelligence

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npj Flexible Electronics 2024年第1期8卷 869-878页

作者： Yunxia Jin Mengxia Yu Dat T.Nguyen Xin Yang Zhipeng Li Ze Xiong Chenhui Li Yuxin Liu Yong Lin Kong John S.Ho Institute for Health Innovation and Technology National University of SingaporeSingapore 117599Singapore Department of Biomedical Engineering National University of SingaporeSingapore 119276Singapore Department of Electrical and Computer Engineering National University of SingaporeSingapore 117583Singapore Integrative Sciences and Engineering Programme National University of Singapore Graduate SchoolSingapore 119077Singapore The N.1 Institute for Health National University of SingaporeSingapore 117456Singapore Institute of Materials Research and Engineering Agency for Science Technology and ResearchSingapore 138634Singapore Department of Mechanical Engineering University of UtahSalt Lake CityUT 84112USA

Wireless and battery-free radio-frequency(RF)sensors can be used to create physical spaces that ambiently sense and respond to human *** such sensors ultra-flexible and transparent is important to preserve the aesthetics of living environments,accommodate daily activities,and functionally integrate with ***,existing RF sensors are unable to simultaneously achieve high transparency,flexibility,and the electrical conductivity required for remote room-scale ***,we report 4.5μm RF tag sensors achieving transparency exceeding 90%that provide capabilities in room-scale ambient wireless *** develop a laser-assisted water-based adhesion-reversion process to digitally realize computer-aided RF design at *** individually tagging multiple objects and regions of the human body,we demonstrate multiplexed wireless tracking of humanenvironment interactions and physiological signals at a range of up to *** radio-frequency identification sensors open opportunities for non-intrusive wireless sensing of daily living spaces for applications in health monitoring and elderly care.

关键词： network ambient transparent

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