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IEEE Transactions on Biomedical Engineering
Journal Prestige (SJR): 1.267
Citation Impact (citeScore): 5
Number of Followers: 35  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0018-9294
Published by IEEE Homepage  [228 journals]
  • Frontcover

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      Abstract: Presents the front cover for this issue of the publication.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • IEEE Engineering in Medicine and Biology Society

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      Abstract: Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • IEEE Transactions on Biomedical Engineering (T-BME)

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      Abstract: These instructions give guidelines for preparing papers for this publication. Presents information for authors publishing in this journal.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • IEEE Transactions on Biomedical Engineering Handling Editors

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      Abstract: Presents a listing of the editorial board, board of governors, current staff, committee members, and/or society editors for this issue of the publication.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • First Clinical Investigation of Near-Infrared Window IIa/IIb Fluorescence
           Imaging for Precise Surgical Resection of Gliomas

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      Authors: Caiguang Cao;Zeping Jin;Xiaojing Shi;Zhe Zhang;Anqi Xiao;Junying Yang;Nan Ji;Jie Tian;Zhenhua Hu;
      Pages: 2404 - 2413
      Abstract: Objective: The near-infrared window II (NIR-II, 1000–1700 nm) imaging, including NIR-IIa (1300–1400 mm) and NIR-IIb (1500-1700 mm), outperforms the near-infrared window I (NIR-I, 700-900 nm) imaging in biological researches. However, the advantages of NIR-IIa/IIb imaging in human study are ambiguous. This study aims to apply the NIR-IIa/IIb imaging to glioma resection and evaluate their performance by using the developed imaging instrument and intraoperative image fusion method. Methods: A multispectral fluorescence imaging instrument that integrated NIR-I/II/IIa/IIb fluorescence imaging and an intraoperative image fusion method have been developed. Seven patients with grade III/IV glioma have been enrolled. NIR-I/II images of the tumor and NIR-I/II/IIa/IIb images of cerebral vessels were acquired with the administration of indocyanine green. Images were fused using the specialized fusion method to synchronously provide the distribution of the vessels and the surgical boundaries. Results: The NIR-IIa/IIb imaging was successfully applied to the clinic. High imaging resolution and contrast have been attained in the NIR-IIa/IIb spectra. Besides, capillaries with an apparent diameter as small as 182 μm were acquired using NIR-IIb imaging. Tumor-feeding arteries were precisely blocked and tumors were excised to the maximum extent for all patients. The blood loss volume during surgery was significantly reduced compared with the control group. Conclusion: The multispectral fluorescence imaging showed high performance, which led to a significant reduction in blood loss volume. Significance: The novel multispec-ral fluorescence imaging technology can assist surgeons in other vascular surgeries in the future.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • Influence of Electrode Configuration on Muscle-Fiber-Conduction-Velocity
           Estimation Using Surface Electromyography

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      Authors: Yaodan Xu;Kaichen Wang;Yibin Jin;Fang Qiu;Yang Yao;Lin Xu;
      Pages: 2414 - 2422
      Abstract: Objective: Muscle fiber conduction velocity (MFCV) is an important myoelectric parameter and can be estimated by analysing surface electromyography (EMG). Among many factors, electrode configuration plays a key role on MFCV estimation. Most studies adopt bipolar configuration (BC) for CV estimation. However, a thorough understanding of the underlying mechanism is lacking, confusing the design of the most appropriate EMG measurement setup for CV estimation. The aim of this study is therefore to systematically investigate the influence of electrode configuration on MFCV estimation. Methods: Four possible configurations are considered, including BC, monopolar configuration (MC), common average reference (CAR), and a special monopolar configuration (SMC) using a fixed channel on the active muscle as reference. For each configuration, mathematical models computing the time delay between adjacent channels are derived and evaluated by dedicated simulation as well as real EMG measurements. MFCV was calculated using the maximum likelihood algorithm with and without channel normalization. Results: The simulation results are in line with the mathematical models. The CVs estimated from the real EMG with and without normalization are 4.3$pm$0.7 and 7.2$pm$3.7 m/s, 5.7$pm$1.3 and 20.4$pm$4.7 m/s, 9.0$pm$3.4 and 20.6$pm$9.8 m/s, and 5.5$pm$2.5 and 5.5$pm$2.4 m/s fo- BC, MC, SMC, and CAR, respectively. Conclusion: Our results show normalized BC to produce the most accurate CV estimation, in line with the mathematical models and the simulation results. Significance: These findings enable a better understanding of the influence of electrode configuration on MFCV estimation, providing useful information for EMG measurement setup design aiming at MFCV studies.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • Hemolytic Footprint of Rotodynamic Blood Pumps

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      Authors: Andreas Escher;Henrike Göbel;Marcel Nicolai;Thomas Schlöglhofer;Emanuel J. Hubmann;Günther Laufer;Barbara Messner;Ulrich Kertzscher;Daniel Zimpfer;Marcus Granegger;
      Pages: 2423 - 2432
      Abstract: Objective: In preclinical examinations, rotodynamic blood pumps (RBPs) are predominantly evaluated at design-point conditions. In clinical practice, however, they run at diversified modes of operation. This study aimed at extending current preclinical evaluation of hemolytic profiles in RBPs toward broader, clinically relevant ranges of operation. Methods: Two implantable RBPs – the HeartMate 3 (HM3) and the HeartWare Ventricular Assist Device (HVAD) – were analyzed at three pump speeds (HM3: 4300, 5600, 7000 rpm; HVAD: 1800, 2760, 3600 rpm) with three flow rates (1-9L/min) per speed setting. Hemolysis measurements were performed in heparinized bovine blood. The delta free hemoglobin (dfHb) and the normalized index of hemolysis (NIH) served as hemolytic measures. Statistical analysis was performed by multiple comparison of the 9 operating conditions. Moreover, computational fluid dynamics (CFD) was applied to provide mechanistic insights into the interrelation between hydraulics and hemolysis by correlating numerically computed hydraulic losses with in-vitro hemolytic measures. Results: In both devices, dfHb increased toward increasing speeds, particularly during low but also during high flow condition. By contrast, in both RBPs magnitudes of NIH were significantly elevated during low flow operation compared to high flow conditions (p0.793). Conclusions: While off-design operation is associated with increased hemolytic profiles, the setting of different operating conditions render a preclinical prediction of clinical impact with current hemolysis metrics difficult. Significance: The identified increase in hemolytic measures during episodes of off-design operation is highlightin- the need to consider worst-case operation during preclinical examinations.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • Analyzing Efficacy and Safety of Anti-Fungal Blue Light Therapy via
           Kernel-Based Modeling the Reactive Oxygen Species Induced by Light

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      Authors: Tianfeng Wang;Jianfei Dong;Guoqi Zhang;
      Pages: 2433 - 2442
      Abstract: Objective: The goal of this study is to investigate the efficacy, safety, and mechanism of ABL for inactivating Candida albicans (C. albicans), and to determine the best wavelength for treating candida infected disease, by experimental measurements and dynamic modeling. Methods: The changes in reactive oxygen species (ROS) in C. albicans and human host cells under the irradiation of 385, 405, and 415 nm wavelengths light with irradiance of 50 $mW/cm^2$ were measured. Moreover, a kernel-based nonlinear dynamic model, i.e., nonlinear autoregressive with exogenous inputs (NARX), was developed and applied to predict the concentration of light-induced ROS, whose kernels were selected by a newly developed algorithm based on particle swarm optimization (PSO). Results: The ROS concentration was increased respectively about 10-12 times in C. albicans and about 3-6 times in human epithelial cells by the ABL treatment with the same fluence of 90 $J/cm^2$. The NARX models were respectively fitted to the data from the experiments on both types of cells. Besides, four different kernel functions, including Gaussian, Laplace, linear and polynomial kernels, were compared in their fitting accuracies. The errors with the Laplace kernel turned out to be only 0.2704 and 0.0593, as respectively fitted to the experimental data of the C. albicans and human host cells. Conclusion: The results demonstrated the effectiveness of the NARX modeling approach, and revealed that the 415 nm light was more effective as an anti-fungal treatment with less damage to the host cells than the 405 or 385 nm light. Significance: The kernel-based NARX model identification algorithm offers opportunities-for determining the effective and safe light dosages in treating various fungal infection diseases.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • Estimation of Changes in Intracardiac Hemodynamics Using Wearable
           Seismocardiography and Machine Learning in Patients With Heart Failure: A
           Feasibility Study

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      Authors: Md Mobashir Hasan Shandhi;Joanna Fan;J. Alex Heller;Mozziyar Etemadi;Liviu Klein;Omer T. Inan;
      Pages: 2443 - 2455
      Abstract: Objective: Tracking changes in hemodynamic congestion and the consequent proactive readjustment of treatment has shown efficacy in reducing hospitalizations for patients with heart failure (HF). However, the cost-prohibitive nature of these invasive sensing systems precludes their usage in the large patient population affected by HF. The objective of this research is to estimate the changes in pulmonary artery mean pressure (PAM) and pulmonary capillary wedge pressure (PCWP) following vasodilator infusion during right heart catheterization (RHC), using changes in simultaneously recorded wearable seismocardiogram (SCG) signals captured with a small wearable patch. Methods: A total of 20 patients with HF (20% women, median age 55 (interquartile range (IQR), 44-64) years, ejection fraction 24 (IQR, 16-43)) were fitted with a wearable sensing patch and underwent RHC with vasodilator challenge. We divided the dataset randomly into a training–testing set (n = 15) and a separate validation set (n = 5). We developed globalized (population) regression models to estimate changes in PAM and PCWP from the changes in simultaneously recorded SCG. Results: The regression model estimated both pressures with good accuracies: root-mean-square-error (RMSE) of 2.5 mmHg and R2 of 0.83 for estimating changes in PAM, and RMSE of 1.9 mmHg and R2 of 0.93 for estimating changes in PCWP for the training-testing set, and RMSE of 2.7 mmHg and R2 of 0.81 for estimating changes in PAM, and RMSE of 2.9 mmHg and R2 of 0.95 for estimating changes in PCWP for the validation set respectively. Conclusion: Changes in wearable SCG signals may be used to track acute changes in intracardiac hemodynamics in patients with HF. Significance: This method holds promise in trac-ing longitudinal changes in hemodynamic congestion in hemodynamically-guided remote home monitoring and treatment for patients with HF.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • SleepTransformer: Automatic Sleep Staging With Interpretability and
           Uncertainty Quantification

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      Authors: Huy Phan;Kaare Mikkelsen;Oliver Y. Chén;Philipp Koch;Alfred Mertins;Maarten De Vos;
      Pages: 2456 - 2467
      Abstract: Background: Black-box skepticism is one of the main hindrances impeding deep-learning-based automatic sleep scoring from being used in clinical environments. Methods: Towards interpretability, this work proposes a sequence-to-sequence sleep-staging model, namely SleepTransformer. It is based on the transformer backbone and offers interpretability of the model's decisions at both the epoch and sequence level. We further propose a simple yet efficient method to quantify uncertainty in the model's decisions. The method, which is based on entropy, can serve as a metric for deferring low-confidence epochs to a human expert for further inspection. Results: Making sense of the transformer's self-attention scores for interpretability, at the epoch level, the attention scores are encoded as a heat map to highlight sleep-relevant features captured from the input EEG signal. At the sequence level, the attention scores are visualized as the influence of different neighboring epochs in an input sequence (i.e. the context) to recognition of a target epoch, mimicking the way manual scoring is done by human experts. Conclusion: Additionally, we demonstrate that SleepTransformer performs on par with existing methods on two databases of different sizes. Significance: Equipped with interpretability and the ability of uncertainty quantification, SleepTransformer holds promise for being integrated into clinical settings.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • Joint Particle Detection and Analysis by a CNN and Adaptive Norm
           Minimization Approach

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      Authors: Michael Baur;Mathias Reisbeck;Oliver Hayden;Wolfgang Utschick;
      Pages: 2468 - 2479
      Abstract: Optical flow cytometry is used as the gold standard in single cell function diagnostics with the drawback of involving high complexity and operator costs. Magnetic flow cytometers try to overcome this problem by replacing optical labeling with magnetic nanoparticles to assign each cell a magnetic fingerprint. This allows operators to obtain rich cell information from a biological sample with minimal sample preparation at near in-vivo conditions in a decentralized environment. A central task in flow cytometry is the determination of cell concentrations and cell parameters, e.g. hydrodynamic diameter. For the acquisition of this information, signal processing is an essential component. Previous approaches mainly focus on the processing of one-cell signals, leaving out superimposed signals originating from cells passing the magnetic sensors in close proximity. In this work, we present a framework for joint cell/particle detection and analysis, which is capable of processing one-cell as well as multi-cell signals. We employ deep learning and compressive sensing in this approach, which involves the minimization of an adaptive norm. We evaluate our method on simulated and experimental signals, the latter being obtained with polymer microparticles. Our results show that the framework is capable of counting cells with a relative error smaller than 2%. Inference of cell parameters works reliably at both low and high noise levels.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • Feasibility of Concentric Electrodes in Contact Irreversible
           Electroporation for Superficial Lesion Treatment

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      Authors: Kosaku Kurata;Hirotaka Naito;Hiroshi Takamatsu;
      Pages: 2480 - 2487
      Abstract: Objective: Contact irreversible electroporation (IRE) is a method for ablating cells by applying electric pulses via surface electrodes in contact with a target tissue. To facilitate the application of the contact IRE to superficial lesion treatment, this study further extended the ablation depth, which had been limited to a 400-μm depth in our previous study, by using concentric electrodes. Methods: A prototype device of concentric electrodes was manufactured using a Teflon-coated copper wire inserted in a copper tube. The ablation area was experimentally determined using a tissue phantom comprising 3D cultured fibroblasts and compared with the electric field distribution obtained using numerical analyses. Results: Experiments showed that cells 540 μm from the surface of the tissue phantom were necrotized by the application of 150 pulses at 100 V. The outline of the ablation area agreed well with the contour line of 0.4 kV/cm acquired by the analyses. The ablation depth predicted for the concentric electrode using this critical electric field was 1.4 times deeper than that for the parallel electrode. For the actual application of treatment, a multiple-electrode device that bundles several pairs of concentric electrodes was developed, and confirmed that to be effective for treating wide areas with a single treatment. Conclusion: The electric field estimated by the analyses with the experimentally determined threshold confirmed that concentric electrodes could attain a deeper ablation than parallel electrodes. Significance: Using the concentric electrodes, we were able to localize ablation to specific target cells with much less damage to neighboring cells.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • Fabrication and Characterization of a Flexible FBG-Based Shape Sensor
           Using Single-Mode Fibers

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      Authors: Samaneh Manavi Roodsari;Sara Freund;Azhar Zam;Georg Rauter;Philippe C. Cattin;
      Pages: 2488 - 2498
      Abstract: Minimally invasive surgical procedures have become the preferable option, as the recovery period and the risk of infections are significantly lower than traditional surgeries. However, the main challenge in using flexible tools for minimal surgical interventions is the lack of precise feedback on their shape and tip position inside the patient's body. Shape sensors based on fiber Bragg gratings (FBGs) can provide accurate shape information depending on their design. One of the most common configurations in FBG-based shape sensors is to attach three single-mode optical fibers with arrays of FBGs in a triangular fashion around a substrate. Usually, the selected substrates dominate the bending stiffness of the sensor probe, as they have a larger diameter and show less flexibility compared to the optical fibers. Although sensors with this configuration can accurately estimate the shape, they cannot be implemented in flexible endoscopes where large deflections are expected. This paper investigates the shape sensor's performance when using a superelastic substrate with a small diameter instead of a substrate with dominating bending stiffness. A generalized model is also designed for characterizing this type of flexible FBG-based shape sensor. Moreover, we evaluated the sensor in single and multi-bend deformations using two shape reconstruction methods.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • A Dual-Modal Imaging Method Combining Ultrasound and Electromagnetism for
           

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      Authors: Haoming Lin;Yi Chen;Siyuan Xie;Mengmeng Yu;Dingqian Deng;Tong Sun;Yuyang Hu;Mian Chen;Siping Chen;Xin Chen;
      Pages: 2499 - 2511
      Abstract: The mechanical and electrical properties of soft tissues are relative to soft tissues’ pathological state. Modern medical imaging devices have shown a trend to multi-modal imaging, which will provide complementary functional information to improve the accuracy of disease diagnosis. However, no method or system can simultaneously measure the mechanical and electrical properties of the soft tissue. In this study, we proposed a novel dual-modal imaging method integrated by shear wave elasticity imaging (SWEI) and Magneto-acousto-electrical tomography (MAET) to measure soft tissue's elasticity and conductivity simultaneously. A dual-modal imaging system based on a linear array transducer is built, and the imaging performances of MAET and SWEI were respectively evaluated by phantoms experiment and in vitro experiment. Conductivity phantom experiments show that the MAET in this dual-modal system can image conductivity gradient as low as 0.4 S/m. The phantom experiments show that the reconstructed 2-D elasticity maps of the phantoms with inclusions with a diameter larger than 5 mm are relatively accurate. In vitro experiments show that the elasticity parameter can significantly distinguish the changes in tissue before and after heating. This study first proposes a method that can simultaneously obtain tissue elasticity and electrical conductivity to the best of our knowledge. Although this paper just carried out the proof of concept experiments of the new method, it demonstrates great potential for disease diagnosis in the future.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • Hybrid Convolutional Networks for End-to-End Event Detection in Concurrent
           PPG and PCG Signals Affected by Motion Artifacts

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      Authors: Davide Marzorati;Andrea Dorizza;Dario Bovio;Caterina Salito;Luca Mainardi;Pietro Cerveri;
      Pages: 2512 - 2523
      Abstract: The accurate detection of physiologically-related events in photopletismographic (PPG) and phonocardiographic (PCG) signals, recorded by wearable sensors, is mandatory to perform the estimation of relevant cardiovascular parameters like the heart rate and the blood pressure. However, the measurement performed in uncontrolled conditions without clinical supervision leaves the detection quality particularly susceptible to noise and motion artifacts. This work proposes a new fully-automatic computational framework, based on convolutional networks, to identify and localize fiducial points in time as the foot, maximum slope and peak in PPG signal and the S1 sound in the PCG signal, both acquired by a custom chest sensor, described recently in the literature by our group. The event detection problem was reframed as a single hybrid regression-classification problem entailing a custom neural architecture to process sequentially the PPG and PCG signals. Tests were performed analysing four different acquisition conditions (rest, cycling, rest recovery and walking). Cross-validation results for the three PPG fiducial points showed identification accuracy greater than 93 % and localization error (RMSE) less than 10 ms. As expected, cycling and walking conditions provided worse results than rest and recovery, however reaching an accuracy greater than 90 % and a localization error less than 15 ms. Likewise, the identification and localization error for S1 sound were greater than 90 % and less than 25 ms. Overall, this study showcased the ability of the proposed technique to detect events with high accuracy not only for steady acquisitions but also during subject movements. We also showed that the proposed network outperformed traditional Shannon-energy-envelope method in the detection of S1 sound, reaching detection performance comparable to state of the art algorithms. Therefore, we argue that coupling chest sensors and d-ep learning processing techniques may disclose wearable devices to unobtrusively acquire health information, being less affected by noise and motion artifacts.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • Knock-In of a Large Reporter Gene via the High-Throughput Microinjection
           of the CRISPR/Cas9 System

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      Authors: Shuxun Chen;Yang Jiao;Fei Pan;Zhangyan Guan;Shuk Han Cheng;Dong Sun;
      Pages: 2524 - 2532
      Abstract: The non-viral delivery of the prokaryotic clustered regularly interspaced short palindromic repeats (CRISPR)-associated protein 9 (Cas9) nuclease system provides promising solutions for gene therapy. However, traditional chemical and physical delivery approaches for gene knock-in are confronted by significant challenges to overcome the drawbacks of low efficiency and high toxicity. An alternative method for directly delivering CRISPR components into single cells is microinjection. Here, we present the high-throughput robotic microinjection of CRISPR machinery plasmids to produce gene insertions. We demonstrate that the microinjection of CRISPR/Cas9 with an enhanced green fluorescent protein (eGFP) donor template into single HepG2 cells can achieve reporter gene knock-in targeting the adeno-associated virus site 1 locus. Homology-directed repair-mediated knock-in can be observed with an efficiency of 41%. Assessment via T7E1 assay indicates that the eGFP knock-in cells exhibit no detectable changes at potential off-target sites. A case study of injecting the eGFP knock-in cells into zebrafish (Danio rerio) embryos to form an in vivo tumor model is conducted. Results demonstrate the efficiency of combining microinjection with the CRISPR/Cas9 system in achieving gene knock-in.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • Predicting Cochlear Implant Electrode Placement Using Monopolar,
           Three-Point and Four-Point Impedance Measurements

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      Authors: Leanne Sijgers;Alexander Huber;Sonia Tabibi;Julian Grosse;Christof Röösli;Patrick Boyle;Kanthaiah Koka;Norbert Dillier;Flurin Pfiffner;Adrian Dalbert;
      Pages: 2533 - 2544
      Abstract: Objective: This study aimed to investigate the relationship between cochlear implant (CI) electrode distances to the cochleas inner wall (the modiolus) and electrical impedance measurements made at the CIs electrode contacts. We introduced a protocol for three-point impedances in which we recorded bipolar impedances in response to monopolar stimulation at a neighboring electrode. We aimed to assess the usability of three-point impedances and two existing CI impedance measurement methods (monopolar and four-point impedances) for predicting electrode positioning during CI insertion. Methods: Impedances were recorded during stepwise CI electrode array insertions in cadaveric human temporal bones. The positioning of the electrodes with respect to the modiolus was assessed at each step using cone beam computed tomography. Linear mixed regression analysis was performed to assess the relationship between the impedances and electrode-modiolar distances. The experimental results were compared to clinical impedance data and to an existing lumped-element model of an implanted CI. Results: Three-point and four-point impedances strongly correlated with electrode-modiolar distance. In contrast, monopolar impedances were only minimally affected by changes in electrode positioning with respect to the modiolus. An overall model specificity of 62% was achieved when incorporating all impedance parameters. This specificity could be increased beyond 73% when prior expectations of electrode positioning were incorporated in the model. Conclusion: Three-point and four-point impedances are promising measures to predict electrode-modiolar distance in real-time during CI insertion. Significance: This work shows how electrical impedance measurements can be used to predict the CIs electrode positioning in a biologically realistic model.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • Interstitial Optical Monitoring of Focal Laser Ablation

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      Authors: Rory Geoghegan;Le Zhang;Alan Priester;Holden H. Wu;Leonard Marks;Shyam Natarajan;
      Pages: 2545 - 2556
      Abstract: Focal laser ablation is a minimally invasive method of treating cancerous lesions in organs such as prostate, liver and brain. Oncologic control is achieved by inducing hyperthermia throughout the target while minimizing damage to surrounding tissue. Consequently, successful clinical outcomes are contingent upon achieving desired ablation volumes. Magnetic resonance thermometry is frequently used to monitor the formation of the induced thermal damage zone and inform the decision to terminate energy delivery. However, due to the associated cost and complexity there is growing interest in the development of alternative approaches. Here we investigate the utility of real-time interstitial interrogation of laser-tissue interaction as an inexpensive alternative monitoring modality that provides direct assessment of tissue coagulation without the need for organ specific calibration. The optical contrast mechanism was determined using a Monte Carlo model. Subsequently, four interstitial probe designs were manufactured and assessed in a tissue mimicking phantom under simultaneous magnetic resonance imaging. Finally, the optimal probe design was evaluated in ex vivo bovine muscle. It was found to be capable of providing sufficient feedback to achieve pre-defined ablation radii in the range 4–7 mm with a mean absolute error of 0.3 mm. This approach provides an inexpensive monitoring modality that may facilitate widespread adoption of focal laser ablation.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • $m^6A$ +Modifications+in+SARS-CoV-2+RNA+Sequencing&rft.title=IEEE+Transactions+on+Biomedical+Engineering&rft.issn=0018-9294&rft.date=2022&rft.volume=69&rft.spage=2557&rft.epage=2568&rft.aulast=Feng;&rft.aufirst=Ruhan&rft.au=Ruhan+Liu;Liang+Ou;Bin+Sheng;Pei+Hao;Ping+Li;Xiaokang+Yang;Guangtao+Xue;Lei+Zhu;Yuyang+Luo;Ping+Zhang;Po+Yang;Huating+Li;David+Dagan+Feng;">Mixed-Weight Neural Bagging for Detecting $m^6A$ Modifications in
           SARS-CoV-2 RNA Sequencing

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      Authors: Ruhan Liu;Liang Ou;Bin Sheng;Pei Hao;Ping Li;Xiaokang Yang;Guangtao Xue;Lei Zhu;Yuyang Luo;Ping Zhang;Po Yang;Huating Li;David Dagan Feng;
      Pages: 2557 - 2568
      Abstract: Objective: The m6A modification is the most common ribonucleic acid (RNA) modification, playing a role in prompting the virus's gene mutation and protein structure changes in the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Nanopore single-molecule direct RNA sequencing (DRS) provides data support for RNA modification detection, which can preserve the potential $m^6A$ signature compared to second-generation sequencing. However, due to insufficient DRS data, there is a lack of methods to find m6A RNA modifications in DRS. Our purpose is to identify $m^6A$ modifications in DRS precisely. Methods: We present a methodology for identifying $m^6A$ modifications that incorporated mapping and extracted features from DRS data. To detect $m^6A$ modifications, we introduce an ensemble method called mixed-weight neural bagging (MWNB), trained with 5-base RNA synthetic DRS containing modified and unmodified $m^6A$. Results: Our MWNB model achieved the highest classification accuracy of 97.85% and AUC of 0.9968. Additionally, we applied the MWNB model to the COVID-19 dataset; the experiment results reveal a strong association with biomedical experiments. Conclusion: Our strategy enables the prediction of $m^6A$ modifications using DRS data and completes the identification of $m^6A$ modifications on the SARS-CoV-2. Significance: The Corona Vir-s Disease 2019 (COVID-19) outbreak has significantly influence, caused by the SARS-CoV-2. An RNA modification called $m^6A$ is connected with viral infections. The appearance of $m^6A$ modifications related to several essential proteins affects proteins’ structure and function. Therefore, finding the location and number of $m^6A$ RNA modifications is crucial for subsequent analysis of the protein expression profile.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • Synergistic Upper-Limb Functional Muscle Connectivity Using Acoustic
           Mechanomyography

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      Authors: C. Sebastian Mancero Castillo;Ravi Vaidyanathan;S. Farokh Atashzar;
      Pages: 2569 - 2580
      Abstract: Functional muscle network is a critical concept in describing functional synergistic muscle synchronization and functional connectivity needed for the execution of complex motor tasks. Muscle network is typically derived from decomposition of intermuscular coherence (IMC) at different frequency bands of multichannel electromyography (EMG) measurements, which potentially limits out-of-clinic applications. In this investigation, we introduce muscle network analysis to assess the functional coordination and functional connectivity of muscles based on mechanomyography (MMG). We focus on a targeted group of muscles vital for activities of daily living (ADLs) in the upper-limb. Functional muscle networks are evaluated for ten able-bodied participants and three upper-limb amputees. Muscle activity was acquired from a custom-made wearable armband of MMG sensors placed over four superficial muscles around the forearm (flexor carpi radialis (FCR), brachioradialis (BR), extensor digitorum communis (EDC), and flexor carpi ulnaris (FCU)) while participants performed four different hand gestures. Muscle connectivity analysis at multiple frequency bands shows significant topographical differences across gestures for low (i.e., $< $5 Hz) and high (i.e., $>$12 Hz) activation frequencies as well as observable network differences between amputee and non-amputee subjects. Results demonstrate MMG can be used for the analysis of functional muscle connectivity and mapping of synergistic functional synchronization of upper-limb muscles in complex movement tasks. The new physiological modality provides key insights into neural circuitry of motor coordination. Findings further offer the concomitant outcomes of demonstrating feasibility of MMG to map muscle coherence from a neurophysiological perspective and providing a me-hanistic basis for its translation in human-robot interface.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • Co-Adaptive Control of Bionic Limbs via Unsupervised Adaptation of Muscle
           Synergies

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      Authors: Dennis Yeung;Irene Mendez Guerra;Ian Barner-Rasmussen;Emilia Siponen;Dario Farina;Ivan Vujaklija;
      Pages: 2581 - 2592
      Abstract: Objective: In this work, we present a myoelectric interface that extracts natural motor synergies from multi-muscle signals and adapts in real-time with new user inputs. With this unsupervised adaptive myocontrol (UAM) system, optimal synergies for control are continuously co-adapted with changes in user motor control, or as a function of perturbed conditions via online non-negative matrix factorization guided by physiologically informed sparseness constraints in lieu of explicit data labelling. Methods: UAM was tested in a set of virtual target reaching tasks completed by able-bodied and amputee subjects. Tests were conducted under normative and electrode perturbed conditions to gauge control robustness with comparisons to non-adaptive and supervised adaptive myocontrol schemes. Furthermore, UAM was used to interface an amputee with a multi-functional powered hand prosthesis during standardized Clothespin Relocation Tests, also conducted in normative and perturbed conditions. Results: In virtual tests, UAM effectively mitigated performance degradation caused by electrode displacement, affording greater resilience over an existing supervised adaptive system for amputee subjects. Induced electrode shifts also had negligible effect on the real world control performance of UAM with consistent completion times (23.91$pm$1.33 s) achieved across Clothespin Relocation Tests in the normative and electrode perturbed conditions. Conclusion: UAM affords comparable robustness improvements to existing supervised adaptive myocontrol interfaces whilst providing additional practical advantages for clinical deployment. Significance: The proposed system uniquely incorporates neuromuscular control principles with unsupervised online learning methods and presents a working example of a freely co-adaptive bionic interface.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • Ultrasound Image Guided and Mixed Reality-Based Surgical System With
           Real-Time Soft Tissue Deformation Computing for Robotic Cervical Pedicle
           Screw Placement

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      Authors: Puxun Tu;Chunxia Qin;Yan Guo;Dongyuan Li;Abel J. Lungu;Huixiang Wang;Xiaojun Chen;
      Pages: 2593 - 2603
      Abstract: Objective: Cervical pedicle screw (CPS) placement surgery remains technically demanding due to the complicated anatomy with neurovascular structures. State-of-the-art surgical navigation or robotic systems still suffer from the problem of hand-eye coordination and soft tissue deformation. In this study, we aim at tracking the intraoperative soft tissue deformation and constructing a virtual-physical fusion surgical scene, and integrating them into the robotic system for CPS placement surgery. Methods: Firstly, we propose a real-time deformation computation method based on the prior shape model and intraoperative partial information acquired from ultrasound images. According to the generated posterior shape, the structure representation of deformed target tissue gets updated continuously. Secondly, a hand tremble compensation method is proposed to improve the accuracy and robustness of the virtual-physical calibration procedure, and a mixed reality based surgical scene is further constructed for CPS placement surgery. Thirdly, we integrate the soft tissue deformation method and virtual-physical fusion method into our previously proposed surgical robotic system, and the surgical workflow for CPS placement surgery is introduced. Results: We conducted phantom and animal experiments to evaluate the feasibility and accuracy of the proposed system. Our system yielded a mean surface distance error of 1.52 $pm$ 0.43 mm for soft tissue deformation computing, and an average distance deviation of 1.04 $pm$ 0.27 mm for CPS placement. Conclusion: Results demonstrate that our system involves tremendous clinical application potential. Significance: Our proposed system promotes the efficiency and safety of the CPS placement surgery.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • Motor Impairment in Stroke Patients Is Associated With Network Properties
           During Consecutive Motor Imagery

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      Authors: Minji Lee;Yun-Hee Kim;Seong-Whan Lee;
      Pages: 2604 - 2615
      Abstract: Objective: Our study aimed to predict the Fugl-Meyer assessment (FMA) upper limb using network properties during motor imagery using electroencephalography (EEG) signals. Methods: The subjects performed a finger tapping imagery task according to consecutive cues. We measured the weighted phase lag index (wPLI) as functional connectivity and directed transfer function (DTF) as causal connectivity in healthy controls and stroke patients. The network properties based on the wPLI and DTF were calculated. We predicted the FMA upper limb using partial least squares regression. Results: A higher DTF in the mu band was observed in stroke patients than in healthy controls. Notably, the difference in local properties at node F3 was negatively correlated with motor impairment in stroke patients. Finally, using significant network properties based on the wPLI and DTF, we predicted motor impairments using the FMA upper limb with a root-mean-square error of 1.68 ($R^{2}$ = 0.97). This outperformed the state-of-the-art predictors. Conclusion: These findings demonstrate that network properties based on functional and causal connectivity were highly associated with motor function in stroke patients. Significance: Our network properties can help calculate the predictor of motor impairments in stroke rehabilitation and provide insight into the neural correlates related to motor function based on EEG after reorganization induced by stroke.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • Quantification and 3D Localization of Magnetically Navigated
           Superparamagnetic Particles Using MRI in Phantom and Swine
           Chemoembolization Models

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      Authors: Ning Li;Cyril Tous;Ivan P. Dimov;Dominic Cadoret;Phillip Fei;Yasamin Majedi;Simon Lessard;Zeynab Nosrati;Katayoun Saatchi;Urs O. Häfeli;An Tang;Samuel Kadoury;Sylvain Martel;Gilles Soulez;
      Pages: 2616 - 2627
      Abstract: Objective: Superparamagnetic nanoparticles (SPIONs) can be combined with tumor chemoembolization agents to form magnetic drug-eluting beads (MDEBs), which are navigated magnetically in the MRI scanner through the vascular system. We aim to develop a method to accurately quantify and localize these particles and to validate the method in phantoms and swine models. Methods: MDEBs were made of Fe3O4 SPIONs. After injected known numbers of MDEBs, susceptibility artifacts in three-dimensional (3D) volumetric interpolated breath-hold examination (VIBE) sequences were acquired in glass and Polyvinyl alcohol (PVA) phantoms, and two living swine. Image processing of VIBE images provided the volume relationship between MDEBs and their artifact at different VIBE acquisitions and post-processing parameters. Simulated hepatic-artery embolization was performed in vivo with an MRI-conditional magnetic-injection system, using the volume relationship to locate and quantify MDEB distribution. Results: Individual MDEBs were spatially identified, and their artifacts quantified, showing no correlation with magnetic-field orientation or sequence bandwidth, but exhibiting a relationship with echo time and providing a linear volume relationship. Two MDEB aggregates were magnetically steered into desired liver regions while the other 19 had no steering, and 25 aggregates were injected into another swine without steering. The MDEBs were spatially identified and the volume relationship showed accuracy in assessing the number of the MDEBs, with small errors (≤ 8.8%). Conclusion and Significance: MDEBs were able to be steered into desired body regions and then localized using 3D VIBE sequences. The resulting volume relationship was linear, robust, and allowed for quantitative analysis of the MDEB distribution.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • Development and Clinical Evaluation of a Novel Foot Stretching Robot That
           Simultaneously Stretches Plantar Fascia and Achilles Tendon for Treatment
           of Plantar Fasciitis

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      Authors: Yusung Kim;Divij Bhatia;Yechan Lee;Yeonhun Ryu;Hyung-Soon Park;
      Pages: 2628 - 2637
      Abstract: Objective: This paper presents the development and clinical evaluation of a foot stretching robot that simultaneously stretches the plantar fascia and Achilles tendon for the treatment of plantar fasciitis. The therapeutic effectiveness of the robot and feasibility of using metatarsophalangeal joint stiffness as an indicator of recovery were identified through the clinical evaluations. Methods: The robot implements an effective foot stretching protocol through a novel mechanism design that simultaneously stretches the plantar fascia and Achilles tendon using a single motor. Thirty patients with plantar fasciitis and fifteen healthy participants volunteered in the cross-sectional clinical evaluation, and nine patients from the patients group participated in the one-month clinical trial. Four main outcomes (Foot Function Index, Visual Analogue Scale-Foot and Ankle, plantar fascia thickness, and metatarsophalangeal joint stiffness) were used for the clinical evaluations. Results: In the cross-sectional clinical evaluation, the symptomatic feet of patients showed moderate negative correlation between normalized metatarsophalangeal joint stiffness and plantar fascia thickness with statistical significance. In the one-month clinical trial, all the main outcomes showed significant improvement after using the developed robot. Comparing our results with previous studies also indicated a therapeutic superiority of our robot for treating plantar fasciitis. Conclusion: Our foot stretching robot had significant therapeutic effect on plantar fasciitis, and normalized metatarsophalangeal joint stiffness measured by our robot could be used as a monitoring indicator for recovery from plantar fasciitis. Significance: This study contributed to practical issues related to treatment of plantar fasciitis, and our results could be applied to effective treatment of plantar fasciitis and progressive monito-ing of recovery.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • A Simple Non-Contact Optical Method to Quantify In-Vivo Sweat Gland
           Activity and Pulsation

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      Authors: Amy Drexelius;Daniel Fehr;Vincent Vescoli;Jason Heikenfeld;Mathias Bonmarin;
      Pages: 2638 - 2645
      Abstract: Objective: Most methods for monitoring sweat gland activity use simple gravimetric methods, which merely measure the average sweat rate of multiple sweat glands over a region of skin. It would be extremely useful to have a method which could quantify individual gland activity in order to improve the treatment of conditions which use sweat tests as a diagnostic tool, such as hyperhidrosis, cystic fibrosis, and peripheral nerve degeneration. Methods: An optical method using an infrared camera to monitor the skin surface temperature was developed. A thermodynamics computer model was then implemented to utilize these skin temperature values along with other environmental parameters, such as ambient temperature and relative humidity, to calculate the sweat rates of individual glands using chemically stimulated and unstimulated sweating. The optical method was also used to monitor sweat pulsation patterns of individual sweat glands. Results: In this preliminary study, the feasibility of the optical approach was demonstrated by measuring sweat rates of individual glands at various bodily locations. Calculated values from this method agree with expected sweat rates given values found in literature. In addition, a lack of pulsatile sweat expulsion was observed during chemically stimulated sweating, and a potential explanation for this phenomenon was proposed. Conclusion: A simple, non-contact optical method to quantify sweat gland activity in-vivo was presented. Significance: This method allows researchers and clinicians to investigate several sweat glands simultaneously, which has the potential to provide more accurate diagnoses and treatment as well as increase the potential utility for wearable sweat sensors.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • Using High-Fidelity Avatars to Advance Camera-Based Cardiac Pulse
           Measurement

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      Authors: Daniel McDuff;Javier Hernandez;Xin Liu;Erroll Wood;Tadas Baltrusaitis;
      Pages: 2646 - 2656
      Abstract: Non-contact physiological measurement has the potential to provide low-cost, non-invasive health monitoring. However, machine vision approaches are often limited by the availability and diversity of annotated video datasets resulting in poor generalization to complex real-life conditions. To address these challenges, this work proposes the use of synthetic avatars that display facial blood flow changes and allow for systematic generation of samples under a wide variety of conditions. Our results show that training on both simulated and real video data can lead to performance gains under challenging conditions. We show strong performance on three large benchmark datasets and improved robustness to skin type and motion. These results highlight the promise of synthetic data for training camera-based pulse measurement; however, further research and validation is needed to establish whether synthetic data alone could be sufficient for training models.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • MRI-Guided Cardiac RF Ablation for Comparing MRI Characteristics of Acute
           Lesions and Associated Electrophysiologic Voltage Reductions

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      Authors: Philippa R. P. Krahn;Labonny Biswas;Sebastian Ferguson;Venkat Ramanan;Jennifer Barry;Sheldon M. Singh;Mihaela Pop;Graham A. Wright;
      Pages: 2657 - 2666
      Abstract: Objective: Radiofrequency (RF) energy delivered to cardiac tissue produces a core ablation lesion with surrounding edema, the latter of which has been implicated in acute procedural failure of Ventricular Tachycardia (VT) ablation and late arrhythmia recurrence. This study sought to investigate the electrophysiological characteristics of acute RF lesions in the left ventricle (LV) visualized with native-contrast Magnetic Resonance Imaging (MRI). Methods: An MR-guided electrophysiology system was used to deliver RF ablation in the LV of 8 swine (9 RF lesions in total), then perform MRI and electroanatomic mapping. The permanent RF lesions and transient edema were delineated via native-contrast MRI segmentation of T1-weighted images and T2 maps respectively. Bipolar voltage measurements were matched with image characteristics of pixels adjacent to the catheter tip. Native-contrast MR visualization was verified with 3D late gadolinium enhanced MRI and histology. Results: The T2-derived edema was significantly larger than the T1-derived RF lesion (2.1$pm$1.5 mL compared to 0.58$pm$0.34 mL; p=0.01). Bipolar voltage was significantly reduced in the presence of RF lesion core (p$< $0.05) and edema (p$< $0.05), with similar trends suggesting that both the permanent lesion and transient edema contributed to the region of reduced voltage. While bipolar voltage was significantly decreased where RF lesions are present (p$< $0.05), voltage did not change -ignificantly with lesion transmurality (p$>$0.05). Conclusion: Permanent RF lesions and transient edema are distinct in native-contrast MR images, but not differentiable using bipolar voltage. Significance: Intraprocedural native-contrast MRI may provide valuable lesion assessment in MR-guided ablation, whose clinical application is now feasible.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • Estimating the Neovascularity of Human Finger Tendon Through
           High-Frequency Ultrasound Micro-Doppler Imaging

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      Authors: Xi-Rui Qiu;Mu-Ting Wang;Hsin Huang;Li-Chieh Kuo;Hsiu-Yu Hsu;Tai-Hua Yang;Fong-Chin Su;Chih-Chung Huang;
      Pages: 2667 - 2678
      Abstract: Objective: Neovascularization of injured tendons prolongs the proliferative phase of healing, but prolonged neovascularization may cause improper healing and pain. Currently, ultrasound Doppler imaging is used for measuring the neovascularization of injured tendons (e.g., Achilles tendon). However, the resolution of state-of-the-art clinical ultrasound machines is insufficient for visualizing the neovascularization in finger tendons. In this study, a high-frequency micro-Doppler imaging (HFμDI) based on 40-MHz ultrafast ultrasound imaging was proposed for visualizing the neovascularization in injured finger tendons during multiple rehabilitation phases. Method: The vessel visibility was enhanced through a block-wise singular value decomposition filter and several curvilinear structure enhancement strategies, including the bowler-hat transform and Hessian-based vessel enhancement filtering. HFμDI was verified through small animal kidney and spleen imaging because the related vessel structure patterns of mice are well studied. Five patients with finger tendon injuries underwent HFμDI examination at various rehabilitation phases after surgery (weeks 11–56), and finger function evaluations were performed for comparisons. Results: The results of small animal experiments revealed that the proposed HFμDI provides excellent microvasculature imaging performance; the contrast-to-noise ratio of HFμDI was approximately 15 dB higher than that of the conventional singular value decomposition filter, and the minimum detectable vessel size for mouse kidney was 35 μm without the use of contrast agent. In the human study, neovascularization was clearly observed in injured finger tendons during the early phase of healing (weeks 11–21), but it regressed from week 52 to 56. -inger rehabilitation appears to help reduce neovascularization; neovascular density decreased by approximately 1.8%–8.0% in participants after 4 weeks of rehabilitation. Conclusion: The experimental results verified the performance of HFμDI for microvasculature imaging and its potential for injured finger tendon evaluations.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • Experimental Study of Aperiodic Plane Wave Imaging for Ultrafast 3-D
           Ultrasound Imaging

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      Authors: Sua Bae;Bae-Hyung Kim;Azra Alizad;Mostafa Fatemi;Tai-Kyong Song;
      Pages: 2679 - 2690
      Abstract: Objective: Although plane wave imaging (PWI) with multiple plane waves (PWs) steered at different angles enables ultrafast three-dimensional (3-D) ultrasonic imaging, there is still a challenging tradeoff between image quality and frame rate. To address this challenge, we recently proposed the aperiodic PWI (APWI) with mathematical analysis and simulation study. In this paper, we demonstrate the feasibility of APWI and evaluate the performance with phantom and in vivo experiments. Methods: APWI with a concentric ring angle pattern (APWI-C) and APWI with a sunflower pattern (APWI-S) are evaluated. For experimental verification of the methods, the experimental results are compared with simulation results in terms of the spatial resolution and the mainlobe-to-sidelobe ratio. In addition, the performance of APWI is compared with that of conventional PWI by using a commercial phantom. To examine the potential for clinical use of APWI, a gallstone phantom study and an in vivo carotid artery experiment are also conducted. Results: In the phantom study, the APWI methods provide a contrast ratio approximately 2–3 dB higher than that of PWI. In a gallstone experiment, the proposed methods yield 3-D rendered stone images more similar to the real stones than PWI. In the in vivo carotid artery images, APWI reduces the clutter artifacts inside the artery. Conclusion: Phantom and in vivo studies show that the APWI enhances the contrast without compromising the spatial resolution and frame rate. Significance: This study experimentally demonstrates the feasibility and advantage of APWI for ultrafast 3-D ultrasonic imaging.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • Exploring Oscillatory Dysconnectivity Networks in Major Depression During
           Resting State Using Coupled Tensor Decomposition

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      Authors: Wenya Liu;Xiulin Wang;Timo Hämäläinen;Fengyu Cong;
      Pages: 2691 - 2700
      Abstract: Dysconnectivity of large-scale brain networks has been linked to major depression disorder (MDD) during resting state. Recent researches show that the temporal evolution of brain networks regulated by oscillations reveals novel mechanisms and neural characteristics of MDD. Our study applied a novel coupled tensor decomposition model to investigate the dysconnectivity networks characterized by spatio-temporal-spectral modes of covariation in MDD using resting electroencephalography. The phase lag index is used to calculate the functional connectivity within each time window at each frequency bin. Then, two adjacency tensors with the dimension of time × frequency × connectivity × subject are constructed for the healthy group and the major depression group. We assume that the two groups share the same features for group similarity and retain individual characteristics for group differences. Considering that the constructed tensors are nonnegative and the components in spectral and adjacency modes are partially consistent among the two groups, we formulate a double-coupled nonnegative tensor decomposition model. To reduce computational complexity, we introduce the low-rank approximation. Then, the fast hierarchical alternative least squares algorithm is applied for model optimization. After clustering analysis, we summarize four oscillatory networks characterizing the healthy group and four oscillatory networks characterizing the major depression group, respectively. The proposed model may reveal novel mechanisms of pathoconnectomics in MDD during rest, and it can be easily extended to other psychiatric disorders.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
  • A Versatile and Shelf-Stable Dielectric Coupling Medium for Microwave
           Imaging

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      Authors: Yuan Fang;Kazem Bakian-Dogaheh;John Stang;Alireza Tabatabaeenejad;Mahta Moghaddam;
      Pages: 2701 - 2712
      Abstract: Objective: To develop a new class of emulsions using a protein-based emulsifier as the coupling fluid for microwave imaging systems. Methods: In this paper, we provide a theoretical basis for engineering shelf-stable dielectric fluids, a step-by-step formulation method, and measurements of complex dielectric properties in the frequency range of 0.5-3 GHz, which can be applicable for many of the recent microwave imaging systems. Results: This medium was primarily designed for long-term stability while providing a controllable range of complex dielectric permittivities given different fractions of its constituents. Consequently, this emulsion shows dielectric stability in open air throughout a 7-day experiment and temperature insensitivity over the range of 0${,^circ }$C to 60${^circ }$. Conclusions: This control over dielectric permittivity enables formulations that tune the background-to-target contrast to the linearizable regime of iterative inverse scattering algorithms. Accordingly, the emulsion conductivity can also be controlled and reduced to maintain the required signal-to-noise ratio within the dynamic range of the imaging system. The new formulation overcomes the practical challenges of engineering coupling fluids for microwave imaging systems, e.g., temporal stability, non-toxic, low sensitivity to temperature variation, and easy formulation from readily available and inexpensive materials. Significance: The achieved properties associated with this new fluid are of particular benefit to microwave imaging systems used in thermal therapy monitoring.
      PubDate: Aug. 2022
      Issue No: Vol. 69, No. 8 (2022)
       
 
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