Determination of resistance at zero and infinite frequencies in bioimpedance spectroscopy for assessment of body composition in babies
This study investigated an alternative data modelling procedure obviating issues associated with BIS measurements in babies and infants. Approach. BIS data are conventionally analysed according to the Cole model describing the impedance response of body tissues to an applied AC current. This approach is susceptible to errors due to capacitive leakage errors of measurement at high frequency. The alternative is to model BIS data based on the resistance –frequency spectrum rather than the reactance-resistance Cole model thereby avoiding capacitive error impacts upon reactance measurements. Main results. The resistance–fre...
Source: Physiological Measurement - May 6, 2024 Category: Physiology Authors: Natalia Pinheiro-Castro, Tamiris Ramos-Silva, Patricia Helen de Carvalho Rond ó and Leigh C Ward Source Type: research
Evaluation of transformation invariant loss function with distance equilibrium in prediction of imaging photoplethysmography characteristics
Objective. Monitoring changes in human heart rate variability (HRV) holds significant importance for protecting life and health. Studies have shown that Imaging Photoplethysmography (IPPG) based on ordinary color cameras can detect the color change of the skin pixel caused by cardiopulmonary system. Most researchers employed deep learning IPPG algorithms to extract the blood volume pulse (BVP) signal, analyzing it predominantly through the heart rate (HR). However, this approach often overlooks the inherent intricate time-frequency domain characteristics in the BVP signal, which cannot be comprehensively deduced solely fro...
Source: Physiological Measurement - May 6, 2024 Category: Physiology Authors: Shangwei Zhu, Shaohua Liu, Xingjian Jing, Bing Li, Hao Liu, Yuchong Yang and Chundong She Source Type: research
LUNet: deep learning for the segmentation of arterioles and venules in high resolution fundus images
This study aims to automate the segmentation of retinal arterioles and venules (A/V) from digital fundus images (DFI), as changes in the spatial distribution of retinal microvasculature are indicative of cardiovascular diseases, positioning the eyes as windows to cardiovascular health. Approach. We utilized active learning to create a new DFI dataset with 240 crowd-sourced manual A/V segmentations performed by 15 medical students and reviewed by an ophthalmologist. We then developed LUNet, a novel deep learning architecture optimized for high-resolution A/V segmentation. The LUNet model features a double dilated convolutio...
Source: Physiological Measurement - May 2, 2024 Category: Physiology Authors: Jonathan Fhima, Jan Van Eijgen, Marie-Isaline Billen Moulin-Roms ée, Heloïse Brackenier, Hana Kulenovic, Valérie Debeuf, Marie Vangilbergen, Moti Freiman, Ingeborg Stalmans and Joachim A Behar Source Type: research
Real-time regurgitation estimation in percutaneous left ventricular assist device fully supported condition using an unscented Kalman filter
Objective. Significant aortic regurgitation is a common complication following left ventricular assist device (LVAD) intervention, and existing studies have not attempted to monitor regurgitation signals and undertake preventive measures during full support. Regurgitation is an adverse event that can lead to inadequate left ventricular unloading, insufficient peripheral perfusion, and repeated episodes of heart failure. Moreover, regurgitation occurring during full support due to pump position offset cannot be directly controlled through control algorithms. Therefore, accurate estimation of regurgitation during percutaneou...
Source: Physiological Measurement - May 2, 2024 Category: Physiology Authors: Anyun Yin, Biyang Wen, Qilian Xie and Ming Dai Source Type: research
A non-invasive approach to skin cancer diagnosis via graphene electrical tattoos and electrical impedance tomography
Objective. Making up one of the largest shares of diagnosed cancers worldwide, skin cancer is also one of the most treatable. However, this is contingent upon early diagnosis and correct skin cancer-type differentiation. Currently, methods for early detection that are accurate, rapid, and non-invasive are limited. However, literature demonstrating the impedance differences between benign and malignant skin cancers, as well as between different types of skin cancer, show that methods based on impedance differentiation may be promising. Approach. In this work, we propose a novel approach to rapid and non-invasive skin cancer...
Source: Physiological Measurement - May 2, 2024 Category: Physiology Authors: Hannah Lee, Zane Johnson, Spencer Denton, Ning Liu, Deji Akinwande, Emily Porter and Dmitry Kireev Source Type: research
Patient-independent, MHD-robust R-peak detection for retrospective gating in cardiac MRI imaging
Objective. In cardiovascular magnetic resonance imaging, synchronization of image acquisition with heart motion (called gating) is performed by detecting R-peaks in electrocardiogram (ECG) signals. Effective gating is challenging with 3T and 7T scanners, due to severe distortion of ECG signals caused by magnetohydrodynamic effects associated with intense magnetic fields. This work proposes an efficient retrospective gating strategy that requires no prior training outside the scanner and investigates the optimal number of leads in the ECG acquisition set. Approach. The proposed method was developed on a data set of 12-lead ...
Source: Physiological Measurement - April 25, 2024 Category: Physiology Authors: Sara Ganassin, Alessandra Galli, Sotir Ouzounov and Claudio Narduzzi Source Type: research
Multi-branch myocardial infarction detection and localization framework based on multi-instance learning and domain knowledge
In this study, we propose two models, MFB-SENET and MFB-DMIL, for MI detection and localization, respectively. Approach. The MFB-SENET model is designed to detect MI, while the MFB-DMIL model is designed to localize MI. The MI localization model employs a specialized attention mechanism to integrate multi-instance learning with domain knowledge. This approach incorporates handcrafted features and introduces a new loss function called lead-loss, to improve MI localization. Grad-CAM is employed to visualize the decision-making process. Main Results. The proposed method was evaluated on the PTB and PTB-XL databases. Under the...
Source: Physiological Measurement - April 25, 2024 Category: Physiology Authors: Xinyue Li, Yangcheng Huang, Yixin Ning, Mingjie Wang and Wenjie Cai Source Type: research
Evaluation of calibrated and uncalibrated optical imaging approaches for relative cerebral oxygen metabolism measurements in awake mice
This study provides a quantitative comparison of these scenarios to evaluate trade-offs that can be vital to the design of blood oxygenation sensitive imaging experiments for rCMRO2 calculation. (Source: Physiological Measurement)
Source: Physiological Measurement - April 23, 2024 Category: Physiology Authors: A E Toader, M Fukuda and A L Vazquez Source Type: research
TSS-ConvNet for electrical impedance tomography image reconstruction
The objective of this study was to propose a novel data-driven method for solving ill-posed inverse problems, particularly in certain conditions such as time-difference electrical impedance tomography for detecting the location and size of bubbles inside a pipe. Approach. We introduced a new layer architecture composed of three paths: spatial, spectral, and truncated spectral paths. The spatial path processes information locally, whereas the spectral and truncated spectral paths provide the network with a global receptive field. This unique architecture helps eliminate the ill-posedness and nonlinearity inherent in the inv...
Source: Physiological Measurement - April 17, 2024 Category: Physiology Authors: Ayman A Ameen, Achim Sack and Thorsten P öschel Source Type: research
Photoplethysmography based atrial fibrillation detection: a continually growing field
Objective. Atrial fibrillation (AF) is a prevalent cardiac arrhythmia associated with significant health ramifications, including an elevated susceptibility to ischemic stroke, heart disease, and heightened mortality. Photoplethysmography (PPG) has emerged as a promising technology for continuous AF monitoring for its cost-effectiveness and widespread integration into wearable devices. Our team previously conducted an exhaustive review on PPG-based AF detection before June 2019. However, since then, more advanced technologies have emerged in this field. Approach. This paper offers a comprehensive review of the latest advan...
Source: Physiological Measurement - April 16, 2024 Category: Physiology Authors: Cheng Ding, Ran Xiao, Weijia Wang, Elizabeth Holdsworth and Xiao Hu Source Type: research
Sensitivity volume as figure-of-merit for maximizing data importance in electrical impedance tomography
Objective. Electrical impedance tomography (EIT) is a noninvasive imaging method whereby electrical measurements on the periphery of a heterogeneous conductor are inverted to map its internal conductivity. The EIT method proposed here aims to improve computational speed and noise tolerance by introducing sensitivity volume as a figure-of-merit for comparing EIT measurement protocols. Approach. Each measurement is shown to correspond to a sensitivity vector in model space, such that the set of measurements, in turn, corresponds to a set of vectors that subtend a sensitivity volume in model space. A maximal sensitivity volum...
Source: Physiological Measurement - April 15, 2024 Category: Physiology Authors: Claire C Onsager, Chulin Wang, Charles Costakis, Can C Aygen, Lauren Lang, Suzan van der Lee and Matthew A Grayson Source Type: research
Visualizing pursed lips breathing of patients with chronic obstructive pulmonary disease through evaluation of global and regional ventilation using electrical impedance tomography
This study aims to explore the possibility of using electrical impedance tomography (EIT) to assess pursed lips breathing (PLB) performance of patients with chronic obstructive pulmonary disease (COPD). Methods. 32 patients with COPD were assigned equally to either the conventional group or the EIT guided group. All patients were taught to perform PLB by a physiotherapist without EIT in the conventional group or with EIT in the EIT guided group for 10 min. The ventilation of all patients in the final test were continuously monitored using EIT and the PLB performances were rated by another physiotherapist before and after r...
Source: Physiological Measurement - April 15, 2024 Category: Physiology Authors: Lin Yang, Zhijun Gao, Xinsheng Cao, Chunchen Wang, Hang Wang, Jing Dai, Yang Liu, Yilong Qin, Meng Dai, Binghua Zhang, Ke Zhao and Zhanqi Zhao Source Type: research
Harmonization of three different accelerometers to classify the 24 h activity cycle
Increasing interest in measuring key components of the 24 h activity cycle (24-HAC) [sleep, sedentary behavior (SED), light physical activity (LPA), and moderate to vigorous physical activity (MVPA)] has led to a need for better methods. Single wrist-worn accelerometers and different self-report instruments can assess the 24-HAC but may not accurately classify time spent in the different components or be subject to recall errors. Objective. To overcome these limitations, the current study harmonized output from multiple complimentary research grade accelerometers and assessed the feasibility and logistical challenges of th...
Source: Physiological Measurement - April 10, 2024 Category: Physiology Authors: Benjamin D Boudreaux, Ginny M Frederick, Patrick J O ’Connor, Ellen M Evans and Michael D Schmidt Source Type: research
Blood flow restriction attenuates surface mechanomyography lateral and longitudinal, but not transverse oscillations during fatiguing exercise
Objective. Surface mechanomyography (sMMG) can measure oscillations of the activated muscle fibers in three axes (i.e. X, Y, and Z-axes) and has been used to describe motor unit activation patterns (X-axis). The application of blood flow restriction (BFR) is common in exercise studies, but the cuff may restrict muscle fiber oscillations. Therefore, the purpose of this investigation was to examine the acute effects of submaximal, fatiguing exercise with and without BFR on sMMG amplitude in the X, Y, and Z-axes among female participants. Approach. Sixteen females (21 ± 1 years) performed two separate exercise bouts to volit...
Source: Physiological Measurement - April 8, 2024 Category: Physiology Authors: Ethan C Hill, Chris E Proppe, Paola M Rivera, Sean M Lubiak, David H Gonzalez Rojas, John E Lawson, Hwan Choi, Hansen Mansy and Joshua L Keller Source Type: research
pyPPG: a Python toolbox for comprehensive photoplethysmography signal analysis
Objective. Photoplethysmography is a non-invasive optical technique that measures changes in blood volume within tissues. It is commonly and being increasingly used for a variety of research and clinical applications to assess vascular dynamics and physiological parameters. Yet, contrary to heart rate variability measures, a field which has seen the development of stable standards and advanced toolboxes and software, no such standards and limited open tools exist for continuous photoplethysmogram (PPG) analysis. Consequently, the primary objective of this research was to identify, standardize, implement and validate key di...
Source: Physiological Measurement - April 7, 2024 Category: Physiology Authors: M árton Á Goda, Peter H Charlton and Joachim A Behar Source Type: research
