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Medical & Biological Engineering & Computing

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https://www.readbyqxmd.com/read/28390003/modifying-motor-unit-territory-placement-in-the-fuglevand-model
#1
Jason W Robertson, Jamie A Johnston
The Fuglevand model is often used to address challenging questions in neurophysiology; however, there are elements of the neuromuscular system unaccounted for in the model. For instance, in some muscles, slow and fast motor units (MUs) tend to reside deep and superficially in the muscle, respectively, necessarily altering the development of surface electromyogram (EMG) power during activation. Thus, the objective of this study was to replace the randomized MU territory (MUT) placement algorithm in the Fuglevand model with an optimized method capable of reflecting these observations...
April 8, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28390002/a-tool-for-validating-mri-guided-strategies-a-digital-breathing-ct-mri-phantom-of-the-abdominal-site
#2
Chiara Paganelli, Paul Summers, Chiara Gianoli, Massimo Bellomi, Guido Baroni, Marco Riboldi
Dynamic magnetic resonance imaging (MRI) is emerging as the elected image modality for organ motion quantification and management in image-guided radiotherapy. However, the lack of validation tools is an open issue for image guidance in the abdominal and thoracic organs affected by organ motion due to respiration. We therefore present an abdominal four-dimensional (4D) CT/MRI digital phantom, including the estimation of MR tissue parameters, simulation of dedicated abdominal MR sequences, modeling of radiofrequency coil response and noise, followed by k-space sampling and image reconstruction...
April 8, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28361357/increasing-accuracy-of-pulse-transit-time-measurements-by-automated-elimination-of-distorted-photoplethysmography-waves
#3
Marit H N van Velzen, Arjo J Loeve, Sjoerd P Niehof, Egbert G Mik
Photoplethysmography (PPG) is a widely available non-invasive optical technique to visualize pressure pulse waves (PWs). Pulse transit time (PTT) is a physiological parameter that is often derived from calculations on ECG and PPG signals and is based on tightly defined characteristics of the PW shape. PPG signals are sensitive to artefacts. Coughing or movement of the subject can affect PW shapes that much that the PWs become unsuitable for further analysis. The aim of this study was to develop an algorithm that automatically and objectively eliminates unsuitable PWs...
March 30, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28357624/a-simple-method-to-reconstruct-the-molar-mass-signal-of-respiratory-gas-to-assess-small-airways-with-a-double-tracer-gas-single-breath-washout
#4
Johannes Port, Ziran Tao, Annika Junger, Christoph Joppek, Philipp Tempel, Kim Husemann, Florian Singer, Philipp Latzin, Sophie Yammine, Joachim H Nagel, Martin Kohlhäufl
For the assessment of small airway diseases, a noninvasive double-tracer gas single-breath washout (DTG-SBW) with sulfur hexafluoride (SF6) and helium (He) as tracer components has been proposed. It is assumed that small airway diseases may produce typical ventilation inhomogeneities which can be detected within one single tidal breath, when using two tracer components. Characteristic parameters calculated from a relative molar mass (MM) signal of the airflow during the washout expiration phase are analyzed...
March 29, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28353133/automatic-recognition-of-severity-level-for-diagnosis-of-diabetic-retinopathy-using-deep-visual-features
#5
Qaisar Abbas, Irene Fondon, Auxiliadora Sarmiento, Soledad Jiménez, Pedro Alemany
Diabetic retinopathy (DR) is leading cause of blindness among diabetic patients. Recognition of severity level is required by ophthalmologists to early detect and diagnose the DR. However, it is a challenging task for both medical experts and computer-aided diagnosis systems due to requiring extensive domain expert knowledge. In this article, a novel automatic recognition system for the five severity level of diabetic retinopathy (SLDR) is developed without performing any pre- and post-processing steps on retinal fundus images through learning of deep visual features (DVFs)...
March 28, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28353132/evaluation-of-the-parameters-affecting-bone-temperature-during-drilling-using-a-three-dimensional-dynamic-elastoplastic-finite-element-model
#6
Yung-Chuan Chen, Yuan-Kun Tu, Jun-Yan Zhuang, Yi-Jung Tsai, Cheng-Yo Yen, Chih-Kun Hsiao
A three-dimensional dynamic elastoplastic finite element model was constructed and experimentally validated and was used to investigate the parameters which influence bone temperature during drilling, including the drill speed, feeding force, drill bit diameter, and bone density. Results showed the proposed three-dimensional dynamic elastoplastic finite element model can effectively simulate the temperature elevation during bone drilling. The bone temperature rise decreased with an increase in feeding force and drill speed, however, increased with the diameter of drill bit or bone density...
March 28, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28343335/a-new-infant-hybrid-respiratory-simulator-preliminary-evaluation-based-on-clinical-data
#7
Barbara Stankiewicz, Krzysztof J Pałko, Marek Darowski, Krzysztof Zieliński, Maciej Kozarski
A new hybrid (numerical-physical) simulator of the respiratory system, designed to simulate spontaneous and artificial/assisted ventilation of preterm and full-term infants underwent preliminary evaluation. A numerical, seven-compartmental model of the respiratory system mechanics allows the operator to simulate global and peripheral obstruction and restriction of the lungs. The physical part of the simulator is a piston-based construction of impedance transformer. LabVIEW real-time software coordinates the work of both parts of the simulator and its interaction with a ventilator...
March 25, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28343334/design-and-test-of-a-microsoft-kinect-based-system-for-delivering-adaptive-visual-feedback-to-stroke-patients-during-training-of-upper-limb-movement
#8
Daniel Simonsen, Mirjana B Popovic, Erika G Spaich, Ole Kæseler Andersen
The present paper describes the design and test of a low-cost Microsoft Kinect-based system for delivering adaptive visual feedback to stroke patients during the execution of an upper limb exercise. Eleven sub-acute stroke patients with varying degrees of upper limb function were recruited. Each subject participated in a control session (repeated twice) and a feedback session (repeated twice). In each session, the subjects were presented with a rectangular pattern displayed on a vertical mounted monitor embedded in the table in front of the patient...
March 25, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28343333/use-of-phase-locking-value-in-sensorimotor-rhythm-based-brain-computer-interface-zero-phase-coupling-and-effects-of-spatial-filters
#9
Wenjuan Jian, Minyou Chen, Dennis J McFarland
Phase-locking value (PLV) is a potentially useful feature in sensorimotor rhythm-based brain-computer interface (BCI). However, volume conduction may cause spurious zero-phase coupling between two EEG signals and it is not clear whether PLV effects are independent of spectral amplitude. Volume conduction might be reduced by spatial filtering, but it is uncertain what impact this might have on PLV. Therefore, the goal of this study was to explore whether zero-phase PLV is meaningful and how it is affected by spatial filtering...
March 25, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28321684/left-ventricular-flow-propagation-velocity-measurement-is-it-cast-in-stone
#10
Bee Ting Chan, Hak Koon Yeoh, Yih Miin Liew, Yang Faridah Abdul Aziz, Ganiga Srinivasaiah Sridhar, Christian Hamilton-Craig, David Platts, Einly Lim
This study aims to investigate the measurement of left ventricular flow propagation velocity, V p, using phase contrast magnetic resonance imaging and to assess the discrepancies resulting from inflow jet direction and individual left ventricular size. Three V p measuring techniques, namely non-adaptive (NA), adaptive positions (AP) and adaptive vectors (AV) method, were suggested and compared. We performed the comparison on nine healthy volunteers and nine post-infarct patients at four measurement positions, respectively, at one-third, one-half, two-thirds and the conventional 4 cm distances from the mitral valve leaflet into the left ventricle...
March 20, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28321683/resistance-training-using-a-novel-robotic-walker-for-over-ground-gait-rehabilitation-a-preliminary-study-on-healthy-subjects
#11
Kyung-Ryoul Mun, Brandon Bao Sheng Yeo, Zhao Guo, Soon Cheol Chung, Haoyong Yu
Strength training is an aspect of gait rehabilitation, which complements balance control and weight-bearing training. However, conventional strength training does not show positive gait outcomes, due to lack of task specificity. Therefore, the aims of this study were to investigate the effects of a resistance force applied at the center of mass (CoM) and to investigate whether this exercise can be used for effective task-specific gait training. Using a novel robotic walker, a consistent resistive force was applied to the CoM of subjects in the posterior direction...
March 20, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28316038/the-impact-of-the-aortic-valve-impairment-on-the-distant-coronary-arteries-hemodynamics-a-fluid-structure-interaction-study
#12
Hossein Mohammadi, Raymond Cartier, Rosaire Mongrain
Atherosclerosis is still the leading cause of death in the developed world. Although its initiation and progression is a complex multifactorial process, it is well known that blood flow-induced wall shear stress (WSS) is an important factor involved in early atherosclerotic plaque initiation. In recent clinical studies, it was established that the regional pathologies of the aortic valve can be involved in the formation of atherosclerotic plaques. However, the impact of hemodynamic effects is not yet fully elucidated for disease initiation and progression...
March 18, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28251444/combining-novelty-detectors-to-improve-accelerometer-based-fall-detection
#13
Carlos Medrano, Raúl Igual, Iván García-Magariño, Inmaculada Plaza, Guillermo Azuara
Research on body-worn sensors has shown how they can be used for the detection of falls in the elderly, which is a relevant health problem. However, most systems are trained with simulated falls, which differ from those of the target population. In this paper, we tackle the problem of fall detection using a combination of novelty detectors. A novelty detector can be trained only with activities of daily life (ADL), which are true movements recorded in real life. In addition, they allow adapting the system to new users, by recording new movements and retraining the system...
March 1, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28247185/cell-segmentation-in-histopathological-images-with-deep-learning-algorithms-by-utilizing-spatial-relationships
#14
Nuh Hatipoglu, Gokhan Bilgin
In many computerized methods for cell detection, segmentation, and classification in digital histopathology that have recently emerged, the task of cell segmentation remains a chief problem for image processing in designing computer-aided diagnosis (CAD) systems. In research and diagnostic studies on cancer, pathologists can use CAD systems as second readers to analyze high-resolution histopathological images. Since cell detection and segmentation are critical for cancer grade assessments, cellular and extracellular structures should primarily be extracted from histopathological images...
February 28, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28243966/robustness-of-two-different-methods-of-monitoring-respiratory-system-compliance-during-mechanical-ventilation
#15
Gaetano Perchiazzi, Christian Rylander, Mariangela Pellegrini, Anders Larsson, Göran Hedenstierna
Robustness measures the performance of estimation methods when they work under non-ideal conditions. We compared the robustness of artificial neural networks (ANNs) and multilinear fitting (MLF) methods in estimating respiratory system compliance (C RS) during mechanical ventilation (MV). Twenty-four anaesthetized pigs underwent MV. Airway pressure, flow and volume were recorded at fixed intervals after the induction of acute lung injury. After consecutive mechanical breaths, an inspiratory pause (BIP) was applied in order to calculate CRS using the interrupter technique...
February 27, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28238175/classification-of-multi-class-motor-imagery-with-a-novel-hierarchical-svm-algorithm-for-brain-computer-interfaces
#16
Enzeng Dong, Changhai Li, Liting Li, Shengzhi Du, Abdelkader Nasreddine Belkacem, Chao Chen
Pattern classification algorithm is the crucial step in developing brain-computer interface (BCI) applications. In this paper, a hierarchical support vector machine (HSVM) algorithm is proposed to address an EEG-based four-class motor imagery classification task. Wavelet packet transform is employed to decompose raw EEG signals. Thereafter, EEG signals with effective frequency sub-bands are grouped and reconstructed. EEG feature vectors are extracted from the reconstructed EEG signals with one versus the rest common spatial patterns (OVR-CSP) and one versus one common spatial patterns (OVO-CSP)...
February 25, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28224272/biomechanical-evaluation-of-reconstruction-plates-with-locking-nonlocking-and-hybrid-screws-configurations-in-calcaneal-fracture-a-finite-element-model-study
#17
Ching-Hsuan Chen, Chinghua Hung, Yu-Chun Hsu, Chen-Sheng Chen, Chao-Ching Chiang
Calcaneal fractures are the most common fractures of the tarsal bones. The stability of fixation is an important factor for successful reconstruction of calcaneal fractures. The purpose of this study was to analyze the biomechanical influence of plate fixation with different combinations of locking and nonlocking screws during early weight-bearing phase. A three-dimensional FE foot model was established using ANSYS software, which comprised bones, cartilages, plantar fascia, and soft tissue. Calcaneal plate was fixed with whole locking (WLS), whole nonlocking (WNS), and hybrid screw configurations for FE analysis...
February 21, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28204998/discrimination-between-emboli-and-artifacts-for-outpatient-transcranial-doppler-ultrasound-data
#18
Blaise Kévin Guépié, Bruno Sciolla, Fabien Millioz, Marilys Almar, Philippe Delachartre
This paper addresses the detection of emboli in transcranial Doppler ultrasound data acquired from an original portable device. The challenge is the removal of several artifacts (motion and voice) intrinsically related to long-duration (up to 1 h 40 mn per patient) outpatient signals monitoring from this device, as well as high intensities due to the stochastic nature of blood flow. This paper proposes an adapted removal procedure. This firstly consists of reducing the background noise and detecting the blood flow in the time-frequency domain using a likelihood method for contour detection...
February 15, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28197810/a-wrist-sensor-and-algorithm-to-determine-instantaneous-walking-cadence-and-speed-in-daily-life-walking
#19
Benedikt Fasel, Cyntia Duc, Farzin Dadashi, Flavien Bardyn, Martin Savary, Pierre-André Farine, Kamiar Aminian
In daily life, a person's gait-an important marker for his/her health status-is usually assessed using inertial sensors fixed to lower limbs or trunk. Such sensor locations are not well suited for continuous and long duration measurements. A better location would be the wrist but with the drawback of the presence of perturbative movements independent of walking. The aim of this study was to devise and validate an algorithm able to accurately estimate walking cadence and speed for daily life walking in various environments based on acceleration measured at the wrist...
February 14, 2017: Medical & Biological Engineering & Computing
https://www.readbyqxmd.com/read/28194649/numerical-modeling-of-percutaneous-auricular-vagus-nerve-stimulation-a-realistic-3d-model-to-evaluate-sensitivity-of-neural-activation-to-electrode-position
#20
Amine M Samoudi, Stefan Kampusch, Emmeric Tanghe, Jozsef C Széles, Luc Martens, Eugenijus Kaniusas, Wout Joseph
OBJECTIVE: Percutaneous stimulation of the auricular branch of the vagus nerve (pVNS) by miniaturized needle electrodes in the auricle gained importance as a treatment for acute and chronic pain. The objective is to establish a realistic numerical model of pVNS and investigate the effects of stimulation waveform, electrodes' depth, and electrodes' position on nerve excitation threshold and the percentage of stimulated nerves. METHODS: Simulations were performed with Sim4Life...
February 13, 2017: Medical & Biological Engineering & Computing
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