219 results on '"Markos G. Tsipouras"'
Search Results
102. Continuous Non-Invasive Glucose Monitoring via Contact Lenses: Current Approaches and Future Perspectives
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David Bamgboje, Alexandros T. Tzallas, Rinkal Shah, Masoud Malekzadeh, Markos G. Tsipouras, Ioannis Smanis, Nikolaos Giannakeas, Iasonas Christoulakis, Gaurav Chavan, Konstantinos Kalafatakis, and Ioannis G. Violaris
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Blood Glucose ,Computer science ,Clinical Biochemistry ,02 engineering and technology ,Biosensing Techniques ,03 medical and health sciences ,0302 clinical medicine ,CLs upper limits ,Lacrimal fluid ,Diabetes Mellitus ,Humans ,Glucose oxidase ,Prospective Studies ,glucose sensor ,biology ,low power ,Continuous glucose monitoring ,Blood Glucose Self-Monitoring ,Non invasive ,Glucose Measurement ,General Medicine ,021001 nanoscience & nanotechnology ,biosensors ,Reliability engineering ,contact lenses ,Chronic disease ,Glucose ,wireless health monitoring ,non-invasive monitoring ,Perspective ,030221 ophthalmology & optometry ,biology.protein ,0210 nano-technology ,Biosensor ,TP248.13-248.65 ,Biotechnology - Abstract
Diabetes mellitus (DM) is a chronic disease that must be carefully managed to prevent serious complications such as cardiovascular disease, retinopathy, nephropathy and neuropathy. Self-monitoring of blood glucose is a crucial tool for managing diabetes and, at present, all relevant procedures are invasive while they only provide periodic measurements. The pain and measurement intermittency associated with invasive techniques resulted in the exploration of painless, continuous, and non-invasive techniques of glucose measurement that would facilitate intensive management. The focus of this review paper is the existing solutions for continuous non-invasive glucose monitoring via contact lenses (CLs) and to carry out a detailed, qualitative, and comparative analysis to inform prospective researchers on viable pathways. Direct glucose monitoring via CLs is contingent on the detection of biomarkers present in the lacrimal fluid. In this review, emphasis is given on two types of sensors: a graphene-AgNW hybrid sensor and an amperometric sensor. Both sensors can detect the presence of glucose in the lacrimal fluid by using the enzyme, glucose oxidase. Additionally, this review covers fabrication procedures for CL biosensors. Ever since Google published the first glucose monitoring embedded system on a CL, CL biosensors have been considered state-of-the-art in the medical device research and development industry. The CL not only has to have a sensory system, it must also have an embedded integrated circuit (IC) for readout and wireless communication. Moreover, to retain mobility and ease of use of the CLs used for continuous glucose monitoring, the power supply to the solid-state IC on such CLs must be wireless. Currently, there are four methods of powering CLs: utilizing solar energy, via a biofuel cell, or by inductive or radiofrequency (RF) power. Although, there are many limitations associated with each method, the limitations common to all, are safety restrictions and CL size limitations. Bearing this in mind, RF power has received most of the attention in reported literature, whereas solar power has received the least attention in the literature. CLs seem a very promising target for cutting edge biotechnological applications of diagnostic, prognostic and therapeutic relevance.
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- 2021
103. Hybrid extreme learning machine approach for heterogeneous neural networks
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Gavin Brown, Alexandros T. Tzallas, Vasileios Christou, Nikolaos Giannakeas, and Markos G. Tsipouras
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0209 industrial biotechnology ,Mean squared error ,Artificial neural network ,Generalization ,business.industry ,Computer science ,Cognitive Neuroscience ,Crossover ,02 engineering and technology ,Hybrid algorithm ,Computer Science Applications ,020901 industrial engineering & automation ,Artificial Intelligence ,Genetic algorithm ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,Artificial intelligence ,business ,Heterogeneous network ,Extreme learning machine - Abstract
In this paper, a hybrid learning approach, which combines the extreme learning machine (ELM) with a genetic algorithm (GA), is proposed. The utilization of this hybrid algorithm enables the creation of heterogeneous single layer neural networks (SLNNs) with better generalization ability than traditional ELM in terms of lower mean square error (MSE) for regression problems or higher accuracy for classification problems. The architecture of this method is not limited to traditional linear neurons, where each input participates equally to the neuron’s activation, but is extended to support higher order neurons which affect the network’s generalization ability. Initially, the proposed heterogeneous hybrid extreme learning machine (He-HyELM) algorithm creates a number of custom created neurons with different structure, which are used for the creation of homogeneous SLNNs. These networks are trained with ELM and an application specific GA evolves them into heterogeneous networks according to a fitness criterion utilizing the uniform crossover operator for the recombination process. After the completion of the evolution process, the network with the best fitness is selected as the most optimal. Experimental results demonstrate that the proposed learning algorithm can get better results than traditional ELM, homogeneous hybrid extreme learning machine (Ho-HyELM) and optimally pruned extreme learning machine (OP-ELM) for homogeneous and heterogeneous SLNNs.
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- 2019
104. Analysis of electroencephalographic signals complexity regarding Alzheimer's Disease
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Katerina D. Tzimourta, Dimitrios G. Tsalikakis, Pantelis Angelidis, Nikolaos Grigoriadis, Panagiotis Ioannidis, Theodora Afrantou, Loukas G. Astrakas, Markos G. Tsipouras, Alexandros T. Tzallas, Maria Karatzikou, Evripidis Glavas, and Nikolaos Giannakeas
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medicine.medical_specialty ,General Computer Science ,medicine.diagnostic_test ,business.industry ,020206 networking & telecommunications ,Regression analysis ,02 engineering and technology ,Disease ,Electroencephalography ,Audiology ,medicine.disease ,Disease cluster ,Sample entropy ,Correlation ,Rhythm ,Control and Systems Engineering ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,Dementia ,020201 artificial intelligence & image processing ,Electrical and Electronic Engineering ,business - Abstract
Alzheimer's Disease (AD) is the most common type of dementia with world prevalence of more than 46 million people. The Mini-Mental State Examination (MMSE) score is used to categorize the severity and evaluate the disease progress. The electroencephalogram (EEG) is a cost-effective diagnostic tool and lately, new methods have developed for MMSE score correlation with EEG markers. In this paper, EEG recordings acquired from 14 patients with mild and moderate AD and 10 control subjects are analyzed in the five EEG rhythms (δ, θ, α, β, γ). Then, 38 linear and non-linear features are calculated. Multiregression linear analysis showed highly correlation of with MMSE score variation with Permutation Entropy of δ rhythm, Sample Entropy of θ rhythm and Relative θ power. Also, the best statistically significant regression models in terms of R2 are at O2 (0.542) and F4 (0.513) electrodes and at posterior (0.365) and left-temporal cluster (0.360).
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- 2019
105. Classification of EEG signals from young adults with dyslexia combining a Brain Computer Interface device and an Interactive Linguistic Software Tool
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Pavlos Christodoulides, Andreas Miltiadous, Katerina D. Tzimourta, Dimitrios Peschos, Georgios Ntritsos, Victoria Zakopoulou, Nikolaos Giannakeas, Loukas G. Astrakas, Markos G. Tsipouras, Konstantinos I. Tsamis, Euripidis Glavas, and Alexandros T. Tzallas
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Signal Processing ,Biomedical Engineering ,Health Informatics - Published
- 2022
106. Machine Learning Algorithms and Statistical Approaches for Alzheimer's Disease Analysis Based on Resting-State EEG Recordings: A Systematic Review
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Dimitrios G. Tsalikakis, Loukas G. Astrakas, Nikolaos Giannakeas, Katerina D. Tzimourta, Markos G. Tsipouras, Vasileios Christou, Alexandros T. Tzallas, and Pantelis Angelidis
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Computer Networks and Communications ,Physical examination ,02 engineering and technology ,Electroencephalography ,Machine learning ,computer.software_genre ,Machine Learning ,03 medical and health sciences ,0302 clinical medicine ,Neuroimaging ,Alzheimer Disease ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,Dementia ,Humans ,Mini–Mental State Examination ,medicine.diagnostic_test ,business.industry ,Deep learning ,Neuropsychology ,Brain ,General Medicine ,medicine.disease ,Support vector machine ,020201 artificial intelligence & image processing ,Artificial intelligence ,business ,Algorithm ,computer ,030217 neurology & neurosurgery ,Algorithms - Abstract
Alzheimer’s Disease (AD) is a neurodegenerative disorder and the most common type of dementia with a great prevalence in western countries. The diagnosis of AD and its progression is performed through a variety of clinical procedures including neuropsychological and physical examination, Electroencephalographic (EEG) recording, brain imaging and blood analysis. During the last decades, analysis of the electrophysiological dynamics in AD patients has gained great research interest, as an alternative and cost-effective approach. This paper summarizes recent publications focusing on (a) AD detection and (b) the correlation of quantitative EEG features with AD progression, as it is estimated by Mini Mental State Examination (MMSE) score. A total of 49 experimental studies published from 2009 until 2020, which apply machine learning algorithms on resting state EEG recordings from AD patients, are reviewed. Results of each experimental study are presented and compared. The majority of the studies focus on AD detection incorporating Support Vector Machines, while deep learning techniques have not yet been applied on large EEG datasets. Promising conclusions for future studies are presented.
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- 2021
107. Improving the Accuracy of Low-Cost Sensor Measurements for Freezer Automation
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Nikolaos Giannakeas, Kyriakos Koritsoglou, Vasileios Christou, Georgios Tsoumanis, Georgios Ntritsos, Markos G. Tsipouras, and Alexandros T. Tzallas
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business.industry ,Computer science ,020208 electrical & electronic engineering ,Refrigerator car ,Refrigeration ,temperature sensor ,02 engineering and technology ,lcsh:Chemical technology ,simple linear regression ,Biochemistry ,Automation ,Atomic and Molecular Physics, and Optics ,Article ,Analytical Chemistry ,Nonlinear system ,0202 electrical engineering, electronic engineering, information engineering ,temperature monitoring ,lcsh:TP1-1185 ,020201 artificial intelligence & image processing ,ComputerSystemsOrganization_SPECIAL-PURPOSEANDAPPLICATION-BASEDSYSTEMS ,Electrical and Electronic Engineering ,business ,Instrumentation ,Simulation - Abstract
In this work, a regression method is implemented on a low-cost digital temperature sensor to improve the sensor&rsquo, s accuracy, thus, following the EN12830 European standard. This standard defines that the maximum acceptable error regarding temperature monitoring devices should not exceed 1 °, C for the refrigeration and freezer areas. The purpose of the proposed method is to improve the accuracy of a low-cost digital temperature sensor by correcting its nonlinear response using simple linear regression (SLR). In the experimental part of this study, the proposed method&rsquo, s outcome (in a custom created dataset containing values taken from a refrigerator) is compared against the values taken from a sensor complying with the EN12830 standard. The experimental results confirmed that the proposed method reduced the mean absolute error (MAE) by 82% for the refrigeration area and 69% for the freezer area&mdash, resulting in the accuracy improvement of the low-cost digital temperature sensor. Moreover, it managed to achieve a lower generalization error on the test set when compared to three other machine learning algorithms (SVM, B-ELM, and OS-ELM).
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- 2020
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108. Fetal Heart Beat detection based on Empirical Mode Decomposition, Signal Quality Indices and Correlation Analysis
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Konstantinos Kalafatakis, Ioannis G. Violaris, Markos G. Tsipouras, Theodoros Lampros, Nikolaos Giannakeas, and Alexandros T. Tzallas
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0209 industrial biotechnology ,Computer science ,business.industry ,Noise (signal processing) ,Noise reduction ,0206 medical engineering ,Fetal heart ,Pattern recognition ,02 engineering and technology ,020601 biomedical engineering ,Blind signal separation ,Hilbert–Huang transform ,Beat detection ,020901 industrial engineering & automation ,Signal quality ,Correlation analysis ,Artificial intelligence ,business - Abstract
The purpose of fetal monitoring during childbirth is the early recognition of any pathological conditions to guide a clinician in early intervention to avoid any complication in the health of the fetus. Non-Invasive Fetal Electrocardiography (NIFECG) represents an alternative fetal monitoring technique. The fetal ECG (fECG) derived from maternal thoracic and abdominal ECG recordings, provides an alternative to typical embryo monitoring means. In addition, it allows for long-term and ambulatory registrations that broaden the diagnostic capabilities for assessing the fetal health. However, in real situations, clear fECG is difficult to extract because it is usually overwhelmed by the dominant maternal ECG and other contaminated noise such as baseline wander and high-frequency interference. In this paper, a novel integrated adaptive methodology based on the combination of blind source separation, empirical mode decomposition, wavelet shrinkage denoising and correlation analysis, for the non-invasive extraction and processing of the FECG, is proposed. The methodology has been evaluated using both real and simulated recordings, and the obtained results indicate it efficiently.
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- 2020
109. Motor data analysis of Parkinson’s disease patients
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Markos G. Tsipouras, Alexandros T. Tzallas, Konstantinos Kalafatakis, Vasiliki Fiska, Nikolaos S. Katertsidis, and Nikolaos Giannakeas
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medicine.medical_specialty ,Parkinson's disease ,business.industry ,0206 medical engineering ,02 engineering and technology ,medicine.disease ,030226 pharmacology & pharmacy ,020601 biomedical engineering ,03 medical and health sciences ,0302 clinical medicine ,Physical medicine and rehabilitation ,Rating scale ,Medicine ,business ,Motor assessment - Abstract
In this manuscript, a methodology for analysing motor signals from Parkinson’s disease (PD) patients is presented. The signals are obtained from PD patients while wearing a glove device and sequentially performing standard motor tests. The signals are processed in order to detect the onset and offset from specific items (items 23-25) of the Unified Parkinson’s Disease Rating Scale (UPDRS) and then the isolated signal parts are analysed in order to quantity the motor findings defined in UPDRS for these items, such as hesitation, movement amplitude and frequency, and rotation range. The obtained results indicate that the methodology can achieve accurate motor assessment (related to ground-truth UPDRS) for both “Off” and “On” stages.
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- 2020
110. Transfer Learning versus Custom CNN Architectures in NAFLD Biopsy Images
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Markos G. Tsipouras, Constantinos T. Angelis, Georgios Tsoumanis, Evripidis Glavas, Roberta Forlano, Vasileios Christou, Alexandros Arjmand, Alexandros T. Tzallas, Pinelopi Manousou, and Nikolaos Giannakeas
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medicine.medical_specialty ,Cirrhosis ,medicine.diagnostic_test ,business.industry ,05 social sciences ,050209 industrial relations ,Gold standard (test) ,medicine.disease ,Convolutional neural network ,Hepatocellular carcinoma ,0502 economics and business ,Nonalcoholic fatty liver disease ,Biopsy ,Medicine ,Radiology ,Steatosis ,business ,Hepatic fibrosis ,050203 business & management - Abstract
Nonalcoholic fatty liver disease (NAFLD) is one of the most frequent liver conditions representing a wide range of intrahepatic disorders, varying from steatosis to nonalcoholic steatohepatitis (NASH). Steatosis refers to the accumulation of benign fat cells, which at higher rates leads to NASH progression, as the major risk factor for hepatic fibrosis and cirrhosis, as well as for hepatocellular carcinoma (HCC). In recent years the medical field has focused on preventing the progression of these diseases, with microscopic biopsy images being the gold standard imaging modality in modern clinical trials. The proposed work aims at the high classification ability of four histological liver structures, by training a convolutional neural network (CNN) and comparing its diagnostic performance with various pre-trained deep CNN architectures. All diagnostic attempts were made on an augmented image dataset, with the new CNN model achieving a 95.8% classification accuracy, while AlexNet emerging as the most efficient architecture with a corresponding performance of 97.8%.
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- 2020
111. Self-Adaptive Hybrid Extreme Learning Machine for Heterogeneous Neural Networks
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Georgios Ntritsos, Nikolaos Giannakeas, Markos G. Tsipouras, Alexandros T. Tzallas, and Vasileios Christou
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Artificial neural network ,Computer science ,business.industry ,020209 energy ,Crossover ,Pattern recognition ,02 engineering and technology ,Hybrid algorithm ,Transfer function ,Operator (computer programming) ,Genetic algorithm ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,Artificial intelligence ,business ,Heterogeneous network ,Extreme learning machine - Abstract
This paper presents a hybrid algorithm for the creation of heterogeneous single layer neural networks (SLNNs). The proposed self-adaptive heterogeneous hybrid extreme learning machine (SA-He-HyELM) trains a series of SLNNs with different neuron types in the hidden layer utilizing the extreme learning machine (ELM) algorithm. These networks are evolved into heterogeneous networks (networks having different combinations of hidden neurons) with the help of a modified genetic algorithm (GA). The algorithm is able to handle two architecturally different neuron types: traditional low order (linear) units and higher order units with different transfer functions. The GA is fully self-adaptive and uses one novel hybrid crossover operator along with a self-adaptive mutation operator in order to retain ELM’s simplicity and minimize the number of parameters need tuning. The experimental part of the current paper involves testing SA-He-HyELM with traditional ELM and other three ELM-based methods. The experimental part utilized a series of regression and classification experiments on relatively large datasets. In all cases the proposed method managed to get lower MSE or higher classification accuracy when compared to the aforementioned methods.
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- 2020
112. Quantification of liver fibrosis—a comparative study
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Pinelopi Manousou, Nikolaos Giannakeas, Roberta Forlano, Alexandros T. Tzallas, Alexandros Arjmand, and Markos G. Tsipouras
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Pathology ,medicine.medical_specialty ,Liver fibrosis ,Image processing ,digital image processing ,lcsh:Technology ,Histological staining ,lcsh:Chemistry ,03 medical and health sciences ,Liver disease ,0302 clinical medicine ,Digital image processing ,Medicine ,General Materials Science ,Instrumentation ,lcsh:QH301-705.5 ,030304 developmental biology ,liver fibrosis ,Fluid Flow and Transfer Processes ,0303 health sciences ,business.industry ,histological staining ,lcsh:T ,Process Chemistry and Technology ,General Engineering ,medicine.disease ,lcsh:QC1-999 ,Computer Science Applications ,lcsh:Biology (General) ,lcsh:QD1-999 ,lcsh:TA1-2040 ,collagen proportional area ,Digital image analysis ,030211 gastroenterology & hepatology ,liver biopsy images ,business ,lcsh:Engineering (General). Civil engineering (General) ,medical image analysis ,lcsh:Physics - Abstract
Liver disease has been targeted as the fifth most common cause of death worldwide and tends to steadily rise. In the last three decades, several publications focused on the quantification of liver fibrosis by means of the estimation of the collagen proportional area (CPA) in liver biopsies obtained from digital image analysis (DIA). In this paper, early and recent studies on this topic have been reviewed according to these research aims: the datasets used for the analysis, the employed image processing techniques, the obtained results, and the derived conclusions. The purpose is to identify the major strengths and “gray-areas” in the landscape of this topic.
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- 2020
113. Uterine EMG Signals Spectral Analysis for Pre-Term Birth Prediction
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Markos G. Tsipouras
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Computer science ,business.industry ,Pattern recognition ,uterine electromyogram ,02 engineering and technology ,electrohysterogram ,03 medical and health sciences ,0302 clinical medicine ,030225 pediatrics ,EHG signal processing ,perdiction ,0202 electrical engineering, electronic engineering, information engineering ,Term Birth ,020201 artificial intelligence & image processing ,Spectral analysis ,Artificial intelligence ,preterm delivery ,business ,Classifier (UML) ,Preterm delivery - Abstract
A methodology for prediction of pre-term births is presented in this paper. The methodology is based on the analysis of EHG signals and data mining techniques. Initially, spectral and non-linear characteristics of the EHG are extracted, forming a pattern that is used to train a classifier to discriminate between term and pre-term cases. The method has been tested using a benchmark EHG database, and the obtained results indicate its effectiveness in accurate pre-term/term labour prediction.
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- 2018
114. Hybrid extreme learning machine approach for homogeneous neural networks
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Vasileios Christou, Markos G. Tsipouras, Nikolalos Giannakeas, and Alexandros T. Tzallas
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Artificial Intelligence ,Cognitive Neuroscience ,Computer Science Applications - Published
- 2018
115. A robust methodology for classification of epileptic seizures in EEG signals
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Markos G. Tsipouras, Nikolaos Giannakeas, Alexandros T. Tzallas, Katerina D. Tzimourta, Dimitrios G. Tsalikakis, Pantelis Angelidis, and Loukas G. Astrakas
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Discrete wavelet transform ,Computer science ,Feature vector ,Biomedical Engineering ,Bioengineering ,02 engineering and technology ,Electroencephalography ,Applied Microbiology and Biotechnology ,03 medical and health sciences ,Epilepsy ,0302 clinical medicine ,Wavelet ,Robustness (computer science) ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,Ictal ,medicine.diagnostic_test ,business.industry ,Pattern recognition ,medicine.disease ,020201 artificial intelligence & image processing ,Artificial intelligence ,False positive rate ,business ,030217 neurology & neurosurgery ,Biotechnology - Abstract
Drug inefficiency in patients with refractory seizures renders epilepsy a life-threatening and challenging brain disorder and stresses the need for accurate seizure detection and prediction methods and more personalized closed-loop treatment systems. In this paper, a multicenter methodology for automated seizure detection based on Discrete Wavelet Transform (DWT) is presented. A decomposition of 5 levels is applied in each EEG segment and five features are extracted from the wavelet coefficients. The extracted feature vector is used to train a Random Forest classifier and discriminate between ictal and interictal data. EEG recordings from the database of University of Bonn and the database of the University Hospital of Freiburg were employed, in an attempt to test the efficiency and robustness of the method. Classification results in both databases are significant, reaching accuracy above 95% and confirming the robustness of the methodology. Sensitivity and False Positive Rate for the Freiburg database reached 99.74% and 0.21/h respectively.
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- 2018
116. High-throughput, machine learning-based quantification of steatosis, inflammation, ballooning, and fibrosis in biopsies from patients with nonalcoholic fatty liver disease
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Alexandros T. Tzallas, Markos G. Tsipouras, Roberta Forlano, Nikolaos Giannakeas, James Maurice, Mark Thursz, Robert D. Goldin, N. Angkathunyakul, Benjamin H. Mullish, Pinelopi Manousou, J. Lloyd, Michael Yee, Medical Research Council, Medical Research Council (MRC), European Association for the Study of Liver, and Imperial College Healthcare NHS Trust- BRC Funding
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Liver Cirrhosis ,Ballooning%, ballooning percentage ,Intraclass correlation ,Biopsy ,JTT, Jonckheere–Terpstra test ,Inflammation%, inflammation percentage ,computer.software_genre ,Severity of Illness Index ,Machine Learning ,0302 clinical medicine ,Non-alcoholic Fatty Liver Disease ,Interquartile range ,Fibrosis ,Nonalcoholic fatty liver disease ,Medicine ,Diagnostics ,medicine.diagnostic_test ,Gastroenterology ,NASH ,Fat%, fat percentage ,Liver ,030220 oncology & carcinogenesis ,Liver biopsy ,030211 gastroenterology & hepatology ,CPA, collagen proportionate area ,NASH, nonalcoholic steatohepatitis ,Machine learning ,Article ,ICC, interclass correlation coefficient ,03 medical and health sciences ,Artificial Intelligence ,Humans ,NASH CRN ,NASH CRN, Nonalcoholic Steatohepatitis Clinical Research Network ,Grading (tumors) ,IQR, interquartile range ,Inflammation ,Hepatology ,Gastroenterology & Hepatology ,business.industry ,1103 Clinical Sciences ,medicine.disease ,FU, follow-up evaluation ,NAFLD, nonalcoholic fatty liver disease ,Artificial intelligence ,Steatosis ,business ,computer ,NAS, nonalcoholic fatty liver disease activity score - Abstract
Background & Aims Liver biopsy is the reference standard for staging and grading nonalcoholic fatty liver disease (NAFLD), but histologic scoring systems are semiquantitative with marked interobserver and intraobserver variation. We used machine learning to develop fully automated software for quantification of steatosis, inflammation, ballooning, and fibrosis in biopsy specimens from patients with NAFLD and validated the technology in a separate group of patients. Methods We collected data from 246 consecutive patients with biopsy-proven NAFLD and followed up in London from January 2010 through December 2016. Biopsy specimens from the first 100 patients were used to derive the algorithm and biopsy specimens from the following 146 were used to validate it. Biopsy specimens were scored independently by pathologists using the Nonalcoholic Steatohepatitis Clinical Research Network criteria and digitalized. Areas of steatosis, inflammation, ballooning, and fibrosis were annotated on biopsy specimens by 2 hepatobiliary histopathologists to facilitate machine learning. Images of biopsies from the derivation and validation sets then were analyzed by the algorithm to compute percentages of fat, inflammation, ballooning, and fibrosis, as well as the collagen proportionate area, and compared with findings from pathologists’ manual annotations and conventional scoring systems. Results In the derivation group, results from manual annotation and the software had an interclass correlation coefficient (ICC) of 0.97 for steatosis (95% CI, 0.95–0.99; P < .001); ICC of 0.96 for inflammation (95% CI, 0.9–0.98; P < .001); ICC of 0.94 for ballooning (95% CI, 0.87–0.98; P
- Published
- 2019
117. Using the Allen gene expression atlas of the adult mouse brain to gain further insight into the physiological significance of TAG-1/Contactin-2
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Konstantinos Kalafatakis, N. Giannakeas, Alexandros Tsimpolis, Markos G. Tsipouras, Alexandros T. Tzallas, Domna Karagogeos, and Ilias Kalafatakis
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Cell type ,Histology ,NFASC ,Gene Expression ,PDGFRA ,In situ hybridization ,Biology ,050105 experimental psychology ,Transcriptome ,03 medical and health sciences ,Mice ,0302 clinical medicine ,Gene expression ,Contactin 2 ,Animals ,0501 psychology and cognitive sciences ,Gene ,Brain Mapping ,General Neuroscience ,05 social sciences ,Brain ,Cell biology ,PTPRZ1 ,Anatomy ,030217 neurology & neurosurgery - Abstract
The anatomic gene expression atlas (AGEA) of the adult mouse brain of the Allen Institute for Brain Science is a transcriptome-based atlas of the adult C57Bl/6 J mouse brain, based on the extensive in situ hybridization dataset of the Institute. This spatial mapping of the gene expression levels of mice under baseline conditions could assist in the formation of new, reasonable transcriptome-derived hypotheses on brain structure and underlying biochemistry, which could also have functional implications. The aim of this work is to use the data of the AGEA (in combination with Tabula Muris, a compendium of single cell transcriptome data collected from mice, enabling direct and controlled comparison of gene expression among cell types) to provide further insights into the physiology of TAG-1/Contactin-2 and its interactions, by presenting the expression of the corresponding gene across the adult mouse brain under baseline conditions and to investigate any spatial genomic correlations between TAG-1/Contactin-2 and its interacting proteins and markers of mature and immature oligodendrocytes, based on the pre-existing experimental or bibliographical evidence. The across-brain correlation analysis on the gene expression intensities showed a positive spatial correlation of TAG-1/Contactin-2 with the gene expression of Plp1, Myrf, Mbp, Mog, Cldn11, Bace1, Kcna1, Kcna2, App and Nfasc and a negative spatial correlation with the gene expression of Cspg4, Pdgfra, L1cam, Ncam1, Ncam2 and Ptprz1. Spatially correlated genes are mainly expressed by mature oligodendrocytes (like Cntn2), while spatially anticorrelated genes are mainly expressed by oligodendrocyte precursor cells. According to the data presented in this work, we propose that even though Contactin-2 expression during development correlates with high plasticity events, such as neuritogenesis, in adulthood it correlates with pathways characterized by low plasticity.
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- 2019
118. An evolutionary algorithm-based optimization method for the classification and quantification of steatosis prevalence in liver biopsy images
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Ioannis G. Tsoulos, Vasileios Christou, Christos Gogos, Euripidis Glavas, Alexandros Arjmand, Markos G. Tsipouras, Alexandros T. Tzallas, and Nikolaos Giannakeas
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Computer engineering. Computer hardware ,General Computer Science ,medicine.diagnostic_test ,business.industry ,Fatty liver ,Evolutionary algorithm ,QA75.5-76.95 ,Disease ,Liver biopsy ,Evolutionary algorithms ,medicine.disease ,Bioinformatics ,Image analysis ,TK7885-7895 ,Liver disease ,Electronic computers. Computer science ,Machine learning ,Biopsy ,medicine ,Steatosis ,Metabolic syndrome ,business ,Steatohepatitis - Abstract
Non-alcoholic fatty liver disease (NAFLD) covers a range of chronic medical conditions varying from hepatocellular inflammation which characterizes nonalcoholic steatohepatitis (NASH) to steatosis, as the key element of a nonalcoholic fatty liver (NAFL). It is globally linked to the increasing prevalence of obesity and other components of metabolic syndrome and is expected to be the main indication for the existence of the liver disease in the coming years. Its eradication has become a major challenge due to the difficulties in clinical diagnosis, complex pathogenesis and the lack of approved therapies. In this study, an automated image analysis method is presented providing quantitative assessments of fat deposition in steatotic liver biopsy specimens. The methodology applies image processing, machine learning and evolutionary algorithm optimization techniques, producing a 1.93% mean classification error compared to the semiquantitative interpretations of specialized hepatologists.
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- 2021
119. Alzheimer’s Disease and Frontotemporal Dementia: A Robust Classification Method of EEG Signals and a Comparison of Validation Methods
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Markos G. Tsipouras, Katerina D. Tzimourta, Panagiotis Ioannidis, Nikolaos Giannakeas, Alexandros T. Tzallas, Andreas Miltiadous, and Theodora Afrantou
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Medicine (General) ,medicine.medical_specialty ,Clinical Biochemistry ,Electroencephalography ,Audiology ,frontotemporal dementia ,Article ,Cross-validation ,R5-920 ,mental disorders ,medicine ,Dementia ,EEG ,Temporal cortex ,medicine.diagnostic_test ,business.industry ,Cognition ,electroencephalogram ,medicine.disease ,Random forest ,classification ,k-fold ,Biomarker (medicine) ,leave-one-patient-out ,business ,Alzheimer’s disease ,dementia ,Frontotemporal dementia - Abstract
Dementia is the clinical syndrome characterized by progressive loss of cognitive and emotional abilities to a degree severe enough to interfere with daily functioning. Alzheimer’s disease (AD) is the most common neurogenerative disorder, making up 50–70% of total dementia cases. Another dementia type is frontotemporal dementia (FTD), which is associated with circumscribed degeneration of the prefrontal and anterior temporal cortex and mainly affects personality and social skills. With the rapid advancement in electroencephalogram (EEG) sensors, the EEG has become a suitable, accurate, and highly sensitive biomarker for the identification of neuronal and cognitive dynamics in most cases of dementia, such as AD and FTD, through EEG signal analysis and processing techniques. In this study, six supervised machine-learning techniques were compared on categorizing processed EEG signals of AD and FTD cases, to provide an insight for future methods on early dementia diagnosis. K-fold cross validation and leave-one-patient-out cross validation were also compared as validation methods to evaluate their performance for this classification problem. The proposed methodology accuracy scores were 78.5% for AD detection with decision trees and 86.3% for FTD detection with random forests.
- Published
- 2021
120. A Method for Fetal Heart Rate Extraction Based on Time-Frequency Analysis.
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Evaggelos C. Karvounis, Markos G. Tsipouras, Dimitrios I. Fotiadis, and Katerina K. Naka
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- 2006
- Full Text
- View/download PDF
121. Deep Learning in Liver Biopsies using Convolutional Neural Networks
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Alexandros T. Tzallas, Evripidis Glavas, Alexandros Arjmand, Markos G. Tsipouras, Roberta Forlano, Pinelopi Manousou, Nikolaos Giannakeas, and Constantinos T. Angelis
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medicine.medical_specialty ,Cirrhosis ,medicine.diagnostic_test ,business.industry ,Deep learning ,05 social sciences ,Supervised learning ,050209 industrial relations ,Gold standard (test) ,medicine.disease ,Convolutional neural network ,digestive system diseases ,Hepatocellular carcinoma ,Liver biopsy ,0502 economics and business ,Nonalcoholic fatty liver disease ,medicine ,Artificial intelligence ,Radiology ,business ,050203 business & management - Abstract
Nonalcoholic fatty liver disease (NAFLD) presents a wide range of pathological conditions, varying from nonalcoholic steatohepatitis (NASH) to cirrhosis and hepatocellular carcinoma (HCC). Their prevalence is characterized by increased fat accumulation and hepatocellular ballooning. They have become a cause of concern among physicians and engineers, as significant implications tend to occur regarding their accurate diagnosis and treatment. Although magnetic resonance, ultrasonography and other noninvasive methods can reveal the presence of NAFLD, image quantitative interpretation through histology has become the gold standard in clinical examinations. The proposed work introduces a fully automated diagnostic tool, taking into account the high discrimination capability of histological findings in liver biopsy images. The developed methodology is based on deep supervised learning and image analysis techniques, with the determination of an efficient convolutional neural network (CNN) architecture, performing eventually a classification accuracy of 95%.
- Published
- 2019
122. EEG Window Length Evaluation for the Detection of Alzheimer’s Disease over Different Brain Regions
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Alexandros T. Tzallas, Nikolaos Grigoriadis, Dimitrios G. Tsalikakis, Katerina D. Tzimourta, Nikolaos Giannakeas, Panagiotis Ioannidis, Loukas G. Astrakas, Markos G. Tsipouras, Pantelis Angelidis, and Theodora Afrantou
- Subjects
Random Forests ,moderate ,Feature vector ,detection ,window length ,02 engineering and technology ,Disease ,Electroencephalography ,Biology ,Article ,Temporal lobe ,lcsh:RC321-571 ,03 medical and health sciences ,0302 clinical medicine ,Rhythm ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,Dementia ,mild ,Alzheimer’s Disease ,EEG ,lcsh:Neurosciences. Biological psychiatry. Neuropsychiatry ,medicine.diagnostic_test ,business.industry ,General Neuroscience ,Pattern recognition ,medicine.disease ,Random forest ,classification ,020201 artificial intelligence & image processing ,Artificial intelligence ,business ,030217 neurology & neurosurgery ,dementia - Abstract
Alzheimer&rsquo, s Disease (AD) is a neurogenerative disorder and the most common type of dementia with a rapidly increasing world prevalence. In this paper, the ability of several statistical and spectral features to detect AD from electroencephalographic (EEG) recordings is evaluated. For this purpose, clinical EEG recordings from 14 patients with AD (8 with mild AD and 6 with moderate AD) and 10 healthy, age-matched individuals are analyzed. The EEG signals are initially segmented in nonoverlapping epochs of different lengths ranging from 5 s to 12 s. Then, a group of statistical and spectral features calculated for each EEG rhythm (&delta, &theta, &alpha, &beta, and &gamma, ) are extracted, forming the feature vector that trained and tested a Random Forests classifier. Six classification problems are addressed, including the discrimination from whole-brain dynamics and separately from specific brain regions in order to highlight any alterations of the cortical regions. The results indicated a high accuracy ranging from 88.79% to 96.78% for whole-brain classification. Also, the classification accuracy was higher at the posterior and central regions than at the frontal area and the right side of temporal lobe for all classification problems.
- Published
- 2019
123. Utilization of the allen gene expression atlas to gain further insight into glucocorticoid physiology in the adult mouse brain
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Nikolaos Giannakeas, Stafford L. Lightman, Georgina M Russell, Konstantinos Kalafatakis, Alexandros T. Tzallas, Markos G. Tsipouras, and Ioannis Charalampopoulos
- Subjects
0301 basic medicine ,Gene Expression ,In situ hybridization ,Biology ,03 medical and health sciences ,Mice ,0302 clinical medicine ,Allen Brain Atlas-Driven Visualizations ,Neurotrophic factors ,Anatomic Gene Expression Atlas ,Gene expression ,Databases, Genetic ,medicine ,Animals ,Receptor ,Gene ,Glucocorticoids ,In Situ Hybridization ,Adult mouse brain ,General Neuroscience ,Gene Expression Profiling ,Brain ,Glucocorticoid biosynthesis ,030104 developmental biology ,Glucocorticoid neurodynamics ,Neuroscience ,030217 neurology & neurosurgery ,Glucocorticoid ,Hormone ,medicine.drug - Abstract
Glucocorticoid neurodynamics are the most crucial determinant of the hormonal effects in the mammalian brain, and depend on multiple parallel receptor and enzymatic systems, responsible for effectively binding with the hormone (and mediating its downstream molecular effects)and altering the local glucocorticoid content (by adding, removing or degrading glucocorticoids), respectively. In this study, we combined different computational tools to extract, process and visualize the gene expression data of 25 genes across 96 regions of the adult C57Bl/6J mouse brain, implicated in glucocorticoid neurodynamics. These data derive from the anatomic gene expression atlas of the adult mouse brain of the Allen Institute for Brain Science, captured via the in situ hybridization technique. A careful interrogation of the datasets referring to these 25 genes of interest, based on a targeted, prior knowledge-driven approach, revealed useful pieces of information on spatial differences in the glucocorticoid-sensitive receptors, in the regional capacity for local glucocorticoid biosynthesis, excretion, conversion to other biologically active forms and degradation. These data support the importance of the corticolimbic system of the mammalian brain in mediating glucocorticoid effects, and particularly hippocampus, as well as the need for intensifying the research efforts on the hormonal role in sensory processing, executive control function, its interplay with brain-derived neurotrophic factor and the molecular basis for the regional susceptibility of the brain to states of prolonged high hormonal levels. Future work could expand this methodology by exploiting Allen Institute's databases from other species, introducing complex tools of data analysis and combined analysis of different sources of biological datasets.
- Published
- 2019
124. OneAppy: An Interactive Platform Providing Novel Marketing Channels and Promoting Product and Services to the Tourism Industry
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Ioannis Paliokas, Nikolaos Katertsidis, Alexandros T. Tzallas, Stella Sylaiou, Vaggelis Nomikos, Konstantinos Votis, Markos G. Tsipouras, Odysseas Tsakai, and Nikolaos Giannakeas
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Product (business) ,Promotion (rank) ,media_common.quotation_subject ,0502 economics and business ,05 social sciences ,050211 marketing ,Architecture ,Marketing ,050203 business & management ,Tourism ,media_common - Abstract
Nowadays, marketers are required to rethink their marketing strategies, and provide innovative approaches, based on new communication technologies, alongside the classic channels of business promotion. OneAppy is a platform based on a new eMarketing model, aiming to provide valuable marketing channels and tools for promoting products/services. After an analysis on related technologies, the architecture and services of the OneAppy platform are presented in respect to the targeted market domains. With OneAppy, a business may develop a powerful web and mobile presence with minimum cost/time and communicate with its clients interactively, offering them information, suggestions, and updates regarding everything that is related to offered services.
- Published
- 2019
125. Modelling Hydrocortisone Pharmacokinetics on a Subcutaneous Pulsatile Infusion Replacement Strategy in Patients with Adrenocortical Insufficiency
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Alexandros T. Tzallas, Theodoros Lampros, Ioannis G. Tsoulos, Nikolaos Giannakeas, Stafford L. Lightman, Ioannis G. Violaris, Markos G. Tsipouras, Georgina M Russell, Eder Zavala, and Konstantinos Kalafatakis
- Subjects
medicine.medical_specialty ,Pharmaceutical Science ,Context (language use) ,Article ,03 medical and health sciences ,Pharmacy and materia medica ,0302 clinical medicine ,Pharmacokinetics ,subcutaneous delivery ,Internal medicine ,Medicine ,Infusion pump ,Circadian rhythm ,030304 developmental biology ,Ultradian rhythm ,Hydrocortisone ,hydrocortisone replacement therapy ,0303 health sciences ,business.industry ,RS1-441 ,Endocrinology ,pharmacokinetic model ,glucocorticoid pulsatility ,glucocorticoid insufficiency ,business ,hormones, hormone substitutes, and hormone antagonists ,030217 neurology & neurosurgery ,Glucocorticoid ,medicine.drug ,Blood sampling - Abstract
In the context of glucocorticoid (GC) therapeutics, recent studies have utilised a subcutaneous hydrocortisone (HC) infusion pump programmed to deliver multiple HC pulses throughout the day, with the purpose of restoring normal circadian and ultradian GC rhythmicity. A key challenge for the advancement of novel HC replacement therapies is the calibration of infusion pumps against cortisol levels measured in blood. However, repeated blood sampling sessions are enormously labour-intensive for both examiners and examinees. These sessions also have a cost, are time consuming and are occasionally unfeasible. To address this, we developed a pharmacokinetic model approximating the values of plasma cortisol levels at any point of the day from a limited number of plasma cortisol measurements. The model was validated using the plasma cortisol profiles of 9 subjects with disrupted endogenous GC synthetic capacity. The model accurately predicted plasma cortisol levels (mean absolute percentage error of 14%) when only four plasma cortisol measurements were provided. Although our model did not predict GC dynamics when HC was administered in a way other than subcutaneously or in individuals whose endogenous capacity to produce GCs is intact, it was found to successfully be used to support clinical trials (or practice) involving subcutaneous HC delivery in patients with reduced endogenous capacity to synthesize GCs.
- Published
- 2021
126. EEG-Based Eye Movement Recognition Using Brain–Computer Interface and Random Forests
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Alexandros T. Tzallas, Katerina D. Tzimourta, Konstantinos Kalafatakis, Vasileios Christou, Nikolaos Giannakeas, Evangelos Antoniou, Pavlos Bozios, and Markos G. Tsipouras
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random forests ,Eye Movements ,Computer science ,Movement ,0206 medical engineering ,02 engineering and technology ,lcsh:Chemical technology ,eye tracking ,01 natural sciences ,Biochemistry ,Article ,Analytical Chemistry ,Naive Bayes classifier ,Humans ,lcsh:TP1-1185 ,EEG ,Electrical and Electronic Engineering ,eye movement ,Instrumentation ,Brain–computer interface ,business.industry ,brain–computer interface ,010401 analytical chemistry ,electrooculogram ,Bayes Theorem ,Electroencephalography ,Signal Processing, Computer-Assisted ,Pattern recognition ,electroencephalogram ,020601 biomedical engineering ,Ensemble learning ,Atomic and Molecular Physics, and Optics ,0104 chemical sciences ,Random forest ,Support vector machine ,Statistical classification ,Brain-Computer Interfaces ,Multilayer perceptron ,Eye tracking ,EPOC Flex ,Artificial intelligence ,business ,Algorithms - Abstract
Discrimination of eye movements and visual states is a flourishing field of research and there is an urgent need for non-manual EEG-based wheelchair control and navigation systems. This paper presents a novel system that utilizes a brain–computer interface (BCI) to capture electroencephalographic (EEG) signals from human subjects while eye movement and subsequently classify them into six categories by applying a random forests (RF) classification algorithm. RF is an ensemble learning method that constructs a series of decision trees where each tree gives a class prediction, and the class with the highest number of class predictions becomes the model’s prediction. The categories of the proposed random forests brain–computer interface (RF-BCI) are defined according to the position of the subject’s eyes: open, closed, left, right, up, and down. The purpose of RF-BCI is to be utilized as an EEG-based control system for driving an electromechanical wheelchair (rehabilitation device). The proposed approach has been tested using a dataset containing 219 records taken from 10 different patients. The BCI implemented the EPOC Flex head cap system, which includes 32 saline felt sensors for capturing the subjects’ EEG signals. Each sensor caught four different brain waves (delta, theta, alpha, and beta) per second. Then, these signals were split in 4-second windows resulting in 512 samples per record and the band energy was extracted for each EEG rhythm. The proposed system was compared with naïve Bayes, Bayes Network, k-nearest neighbors (K-NN), multilayer perceptron (MLP), support vector machine (SVM), J48-C4.5 decision tree, and Bagging classification algorithms. The experimental results showed that the RF algorithm outperformed compared to the other approaches and high levels of accuracy (85.39%) for a 6-class classification are obtained. This method exploits high spatial information acquired from the Emotiv EPOC Flex wearable EEG recording device and examines successfully the potential of this device to be used for BCI wheelchair technology.
- Published
- 2021
127. Stopping rules for a parallel genetic algorithm
- Author
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Dimitrios G. Tsalikakis, Markos G. Tsipouras, Alexandros T. Tzallas, Vasileios Christou, and Ioannis G. Tsoulos
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Computer science ,Parallel algorithm ,Stopping rules ,Function (mathematics) ,Algorithm ,Parallel genetic algorithm - Abstract
A novel method for the implementation of parallel genetic algorithms is introduced to locate the global minimum of a multidimensional function inside a rectangular hyperbox. The algorithm relies on...
- Published
- 2020
128. Random Forests with Stochastic Induction of Decision Trees
- Author
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Alexandros T. Tzallas, Nikolaos Giannakeas, Markos G. Tsipouras, Dimosthenis C. Tsouros, and Panagiotis N. Smyrlis
- Subjects
Stochastic process ,Computer science ,020204 information systems ,0202 electrical engineering, electronic engineering, information engineering ,Decision tree ,020201 artificial intelligence & image processing ,02 engineering and technology ,Algorithm ,Classifier (UML) ,Subspace topology ,Random forest - Abstract
In this paper, a novel stochastic approach for the induction of the decision trees in a tree-structured ensemble classifier is presented. The proposed algorithm is based on a stochastic process to induct each decision tree, assigning a probability for the selection of the split attribute in every tree node, designed in order to create strong and independent trees. A selection of 33 well-known classification datasets have been employed for the evaluation of the proposed algorithm, obtaining high classification results, in terms of Classification Accuracy, Average Sensitivity and Average Precision. Furthermore, a comparative study with Random Forest, Random Subspace and C4.5 is performed. The obtained results indicate the importance of the proposed algorithm, since it achieved the highest overall results in all metrics.
- Published
- 2018
129. Training of Deep Convolutional Neural Networks to Identify Critical Liver Alterations in Histopathology Image Samples
- Author
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Constantinos T. Angelis, Vasileios Christou, Markos G. Tsipouras, Pinelopi Manousou, Nikolaos Giannakeas, Alexandros T. Tzallas, Evripidis Glavas, Alexandros Arjmand, and Roberta Forlano
- Subjects
Computer science ,02 engineering and technology ,Convolutional neural network ,computer vision ,03 medical and health sciences ,0302 clinical medicine ,convolutional neural networks ,Nonalcoholic fatty liver disease ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,General Materials Science ,Instrumentation ,fatty liver ,Fluid Flow and Transfer Processes ,Artificial neural network ,liver biopsies ,business.industry ,Process Chemistry and Technology ,Deep learning ,Supervised learning ,Fatty liver ,General Engineering ,deep learning ,Pattern recognition ,medicine.disease ,Computer Science Applications ,hepatocyte ballooning ,Multilayer perceptron ,020201 artificial intelligence & image processing ,030211 gastroenterology & hepatology ,Artificial intelligence ,business ,Classifier (UML) - Abstract
Nonalcoholic fatty liver disease (NAFLD) is responsible for a wide range of pathological disorders. It is characterized by the prevalence of steatosis, which results in excessive accumulation of triglyceride in the liver tissue. At high rates, it can lead to a partial or total occlusion of the organ. In contrast, nonalcoholic steatohepatitis (NASH) is a progressive form of NAFLD, with the inclusion of hepatocellular injury and inflammation histological diseases. Since there is no approved pharmacotherapeutic solution for both conditions, physicians and engineers are constantly in search for fast and accurate diagnostic methods. The proposed work introduces a fully automated classification approach, taking into consideration the high discrimination capability of four histological tissue alterations. The proposed work utilizes a deep supervised learning method, with a convolutional neural network (CNN) architecture achieving a classification accuracy of 95%. The classification capability of the new CNN model is compared with a pre-trained AlexNet model, a visual geometry group (VGG)-16 deep architecture and a conventional multilayer perceptron (MLP) artificial neural network. The results show that the constructed model can achieve better classification accuracy than VGG-16 (94%) and MLP (90.3%), while AlexNet emerges as the most efficient classifier (97%).
- Published
- 2019
130. Evaluation of Window Size in Classification of Epileptic Short-Term EEG Signals Using a Brain Computer Interface Software
- Author
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Alexandros T. Tzallas, Dimitrios G. Tsalikakis, A. M. Gianni, Nikolaos Giannakeas, Ioannis Paliokas, Markos G. Tsipouras, Loukas G. Astrakas, and Katerina D. Tzimourta
- Subjects
OpenVibe ,Computer science ,Decision tree ,seizure detection ,02 engineering and technology ,Electroencephalography ,brain computer interface ,03 medical and health sciences ,0302 clinical medicine ,Software ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,window size ,EEG ,Brain–computer interface ,medicine.diagnostic_test ,business.industry ,Pattern recognition ,ComputingMethodologies_PATTERNRECOGNITION ,Seizure detection ,epilepsy ,020201 artificial intelligence & image processing ,Artificial intelligence ,business ,Classifier (UML) ,030217 neurology & neurosurgery - Abstract
The complexity of epilepsy created a fertile ground for further research in automated methods, attempting to help the epileptologists’ task. Over the past years, great breakthroughs have emerged in computer-aided analysis. Furthermore, the advent of Brain Computer Interface (BCI) systems has facilitated significantly the automated seizure analysis. In this study, an evaluation of the window size in automated seizure detection is proposed. The EEG signals from the University of Bonn was employed and segmented into 24 epochs of different window lengths with 50% overlap each time. Statistical and spectral features were extracted in the OpenViBE scenario and were used to train four different classifiers. Results in terms of accuracy were above 80% for the Decision Tree classifier. Also, results indicated that different window sizes provide small variations in classification accuracy.
- Published
- 2018
- Full Text
- View/download PDF
131. Constrained K-Means Classification
- Author
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Panagiotis N. Smyrlis, Markos G. Tsipouras, and Dimosthenis C. Tsouros
- Subjects
020205 medical informatics ,business.industry ,Computer science ,k-means ,Supervised learning ,k-means clustering ,Centroid ,Pattern recognition ,02 engineering and technology ,Class (biology) ,supervised learning ,Euclidean distance ,03 medical and health sciences ,0302 clinical medicine ,ComputingMethodologies_PATTERNRECOGNITION ,Simple (abstract algebra) ,0202 electrical engineering, electronic engineering, information engineering ,030212 general & internal medicine ,Artificial intelligence ,Hypercube ,business ,Cluster analysis ,classification-via-clustering - Abstract
Classification-via-clustering (CvC) is a widely used method, using a clustering procedure to perform classification tasks. In this paper, a novel K-Means-based CvC algorithm is presented, analysed and evaluated. Two additional techniques are employed to reduce the effects of the limitations of K-Means. A hypercube of constraints is defined for each centroid and weights are acquired for each attribute of each class, for the use of a weighted Euclidean distance as a similarity criterion in the clustering procedure. Experiments are made with 42 well–known classification datasets. The experimental results demonstrate that the proposed algorithm outperforms CvC with simple K-Means.
- Published
- 2018
- Full Text
- View/download PDF
132. EEG-Based Automatic Sleep Stage Classification
- Author
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Katerina D. Tzimourta, Alexandros T. Tzallas, Athanasios Tsilimbaris, Katerina Tzioukalia, Loukas G. Astrakas, Nikolaos Giannakeas, and Markos G. Tsipouras
- Subjects
0301 basic medicine ,Discrete wavelet transform ,Stage classification ,medicine.diagnostic_test ,Computer science ,Speech recognition ,Cardiac activity ,02 engineering and technology ,General Medicine ,Electroencephalography ,Respiratory activity ,Sleep in non-human animals ,03 medical and health sciences ,030104 developmental biology ,Alpha rhythm ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,020201 artificial intelligence & image processing - Published
- 2018
133. Fat Droplets Identification in Liver Biopsies using Supervised Learning Techniques
- Author
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Markos G. Tsipouras, Alexandros T. Tzallas, Pinelopi Manousou, Nikolaos Giannakeas, Nikolaos S. Katertsidis, Alexandros Arjmand, and Roberta Forlano
- Subjects
Pathology ,medicine.medical_specialty ,Cirrhosis ,medicine.diagnostic_test ,Computer science ,Fatty liver ,Histology ,Disease ,medicine.disease ,03 medical and health sciences ,0302 clinical medicine ,Insulin resistance ,Fibrosis ,030220 oncology & carcinogenesis ,Liver biopsy ,medicine ,030211 gastroenterology & hepatology ,Steatohepatitis - Abstract
Non-Alcoholic Fatty Liver Disease (NAFLD) is a frequent syndrome that exclusively refers to fat accumulation in liver and steatohepatitis1. It is considered as a massive disease ranging from 20% to 40% in adult populations of the Western World. Its prevalence is related to insulin resistance, which places individuals at high rates of mortality. An increased fat accumulation rate, can significantly increase the development of liver steatosis, which in later stages may progress into fibrosis and cirrhosis. In recent years, research groups focus on the automated fat detection based on histology and digital image processing. The current project, extends our previous work for the detection and quantification of fatty liver, by characterizing histological findings. It is an extensive study of supervised learning of fat droplet features, in order to exclude other findings from fat ratio computation. The method is evaluated on a set of 13 liver biopsy images, performing 92% accuracy.
- Published
- 2018
134. A generalized methodology for the gridding of microarray images with rectangular or hexagonal grid
- Author
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Dimitrios I. Fotiadis, Fanis G. Kalatzis, Nikolaos Giannakeas, and Markos G. Tsipouras
- Subjects
Measure (data warehouse) ,Hexagonal crystal system ,Computer science ,Ranging ,02 engineering and technology ,Substrate (printing) ,computer.software_genre ,030218 nuclear medicine & medical imaging ,Image (mathematics) ,03 medical and health sciences ,0302 clinical medicine ,Signal Processing ,0202 electrical engineering, electronic engineering, information engineering ,Gene chip analysis ,020201 artificial intelligence & image processing ,Multimedia information systems ,Data mining ,Electrical and Electronic Engineering ,computer ,Hexagonal tiling - Abstract
Microarrays provide a simple way to measure the level of hybridization of known probes of interest with one or more samples under different conditions. The rapid development of microarray technology requires the implementation of smart and flexible algorithms to deal either with the great amount of data or with the variations of the used hardware. In this paper, a generalized methodology for spot addressing and gridding of microarray images is presented. The methodology can cope with both rectangular and hexagonal grids, which are used for the probes placement onto the substrate. Initially, the methodology identifies the structure of the image, and an efficient spot-by-spot approach has been developed for the detection of all spots in the image. The evaluation of the methodology was performed using both rectangular and hexagonal structured images, merged in a single dataset. The methodology results in high accuracy in the spots detection, ranging from 92.8 to 99.8 % depending on the dataset used.
- Published
- 2015
135. Epileptic Seizures Classification Based on Long-Term EEG Signal Wavelet Analysis
- Author
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Katerina D. Tzimourta, Nikolaos Giannakeas, Markos G. Tsipouras, Loukas G. Astrakas, Alexandros T. Tzallas, and Dimitrios G. Tsalikakis
- Subjects
Discrete wavelet transform ,medicine.diagnostic_test ,Computer science ,business.industry ,Feature vector ,Pattern recognition ,02 engineering and technology ,Neurological disorder ,Electroencephalography ,medicine.disease ,Support vector machine ,03 medical and health sciences ,Epilepsy ,0302 clinical medicine ,Wavelet ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,020201 artificial intelligence & image processing ,Ictal ,Artificial intelligence ,business ,030217 neurology & neurosurgery - Abstract
Epilepsy is a complex neurological disorder recognized by abnormal synchronization of cerebral neurons, named seizures. During the last decades, significant progress has been done in automated detection and prediction of seizures, aiming to develop personalized closed-loop intervention systems. In this paper, a methodology for automated seizure detection based on Discrete Wavelet Transform (DWT) is presented. Twenty-one intracranial ictal recordings acquired from the database of University Hospital of Freiburg are firstly segmented in 2 s epochs. Then, a five-level decomposition is applied in each segment and five features are extracted from the wavelet coefficients. The extracted feature vector is used to train a Support Vector Machines (SVM) classifier. Average sensitivity and specificity reached above 93% and 99% respectively.
- Published
- 2017
136. Rule Editor for ARDEN Syntax Generation towards a more Effective Self-Management of Asthma Disease Patients
- Author
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Konstantinos Votis, Nikolaos Giannakeas, Stefanos Doumpoulakis, Dimitrios Kikidis, Antonis Voulgaridis, Dimitrios Tzovaras, and Markos G. Tsipouras
- Subjects
Decision support system ,Self-management ,business.industry ,Computer science ,computer.file_format ,Disease ,Disjunctive normal form ,medicine.disease ,Set (abstract data type) ,03 medical and health sciences ,Arden syntax ,0302 clinical medicine ,Work (electrical) ,030225 pediatrics ,medicine ,030212 general & internal medicine ,Software engineering ,business ,computer ,Asthma - Abstract
The Decision Support tool of the myAirCoach platform is presented in this work. MyAirCoach is a web-based platform for personalized management of asthma patients. The Decision Support tool is used from medical experts to generate knowledge-based rules for asthma patients. The tool is a web-based application that includes a simple-to-use rule editor for generating medical rules in Arden Syntax, which is an HL7 standard. The logic of the rules in formulated in disjunctive normal form. Using the this tool, medical experts can generate rules and specify the set of rules that are applicable for alerting each patient, thus creating a personalized decision support system for asthma patients.
- Published
- 2017
137. Protein Structure Recognition by Means of Sequential Pattern Mining
- Author
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Alexandros T. Tzallas, Nikolaos Giannakeas, Anna N. Ntagiou, and Markos G. Tsipouras
- Subjects
business.industry ,Computer science ,Pattern recognition ,02 engineering and technology ,Protein structure prediction ,Prediction algorithms ,ComputingMethodologies_PATTERNRECOGNITION ,Protein structure ,020204 information systems ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,Artificial intelligence ,Sequential Pattern Mining ,business ,Protein secondary structure - Abstract
In this work, an innovative classification algorithmic technique through sequential pattern mining was developed to predict the secondary structure of proteins. A basic algorithm was selected for the extraction of the sequential patterns and another algorithm was developed which employs these patterns for protein structure prediction. In the matter of predicting protein structures and scoring sequential patterns, several methodologies has been implemented that theoretically and experimentally overcome the disadvantages of existing algorithms.
- Published
- 2017
138. PWE-093 Development and validation of an automated system for assessment of liver steatosis and fibrosis in routine: histological images in patients with non-alcoholic fatty liver disease
- Author
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Robert D. Goldin, James Maurice, Michael Yee, E. Goldin, Gaetano Serviddio, Mark Thursz, P. Manousou, Nikolaos Giannakeas, N. Angkathunyakul, Roberta Forlano, Benjamin H. Mullish, Markos G. Tsipouras, F Rui, Alexandros T. Tzallas, Imperial College Healthcare NHS Trust- BRC Funding, Imperial College Healthcare NHS Trust, Imperial College Healthcare Charity, and St Stephen's Aids Trust
- Subjects
medicine.medical_specialty ,Gastroenterology & Hepatology ,medicine.diagnostic_test ,business.industry ,Fatty liver ,H&E stain ,1103 Clinical Sciences ,Gold standard (test) ,medicine.disease ,Gastroenterology ,chemistry.chemical_compound ,chemistry ,Fibrosis ,Liver biopsy ,Internal medicine ,1114 Paediatrics And Reproductive Medicine ,medicine ,Steatosis ,Stage (cooking) ,business ,Sirius Red - Abstract
Introduction Liver biopsy is the gold standard method for diagnosing and staging NAFLD, up to date,the steatosis grade and fibrosis stage are reported using semi-quantitative scores with hisg Inter-observer variability.We aimed to develop an automated method for steatosis and fibrosis quantitation using routine histological images of NAFLD patients. Method 118 consecutive patients with biopsy-confirmed NAFLD were retrospectively evaluated. Biopsies were stained with H and E and Sirius red, and then scored by two histopathologists. Each image was then analysed by the automated software in two stages: Machine learning clustering and MorphologicalImage Processing (Figure 1). Fat% and fibrosis% computed by the software were compared with the manual annotationfor all cases. Results There was good correlation between fat% and steatosis grade but with significant overlap between groups: Anova 50.9,p Conclusion Our fully automated software uses low-resolution images widely available and shows excellent correlationwith experts’ annotation. There is wide variation in both fat and fibrosis quantitation within each grade and stage with considerable overlap. Computerised quantitative assessment produces more objective measurements which increase the sensitivity to show response to interventions. Disclosure of Interest None Declared
- Published
- 2017
139. Automated Collagen Proportional Area Extraction in Liver Biopsy Images Using a Novel Classification via Clustering Algorithm
- Author
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Dimitrios G. Tsalikakis, Pinelopi Manousou, Dimosthenis C. Tsouros, Nikolaos Giannakeas, Markos G. Tsipouras, Panagiotis N. Smyrlis, and Alexandros T. Tzallas
- Subjects
Pathology ,medicine.medical_specialty ,medicine.diagnostic_test ,business.industry ,Centroid ,Image processing ,Pattern recognition ,02 engineering and technology ,Image segmentation ,03 medical and health sciences ,Statistical classification ,0302 clinical medicine ,Liver biopsy ,Biopsy ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,030211 gastroenterology & hepatology ,020201 artificial intelligence & image processing ,Artificial intelligence ,Hypercube ,business ,Cluster analysis - Abstract
Diagnosis and staging of liver diseases are essential for the therapeutic efficacy of medication and treatment strategies. Measuring the Collagen Proportional Area (CPA) in liver biopsies recently becomes an effective tool for the assessment of fibrosis in liver tissues. State of the art image processing techniques are employed to analyze biopsy images, providing objective assessment of diseases severity. In current work a novel modification of K-means clustering is proposed for image segmentation of liver biopsies. More specifically, supervised restriction of centroids movement is utilized. In the first stage, a training set of images are employed to extract a hypercube for each class. Then, one centroid is initialized inside each hypercube and during the iterations of the clustering is allowed to move only inside the hypercube. For the evaluation of the proposed method 8 liver biopsy images are employed and classification results along with CPA values are computed for each image.
- Published
- 2017
140. EEG Classification and Short-Term Epilepsy Prognosis Using Brain Computer Interface Software
- Author
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Spyridon Konitsiotis, Markos G. Tsipouras, Kostantinos N. Zoulis, Nikolaos Giannakeas, Katerina D. Tzimourta, Alexandros T. Tzallas, E. Glavas, and Loukas G. Astrakas
- Subjects
medicine.diagnostic_test ,business.industry ,Computer science ,Speech recognition ,Interface (computing) ,Feature extraction ,02 engineering and technology ,Electroencephalography ,medicine.disease ,03 medical and health sciences ,Epilepsy ,Statistical classification ,ComputingMethodologies_PATTERNRECOGNITION ,0302 clinical medicine ,Software ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,020201 artificial intelligence & image processing ,Epileptic seizure ,medicine.symptom ,business ,030217 neurology & neurosurgery ,Brain–computer interface - Abstract
The recent advances of Brain Computer Interfaces (BCI) systems, can provide effective assistance for real time prognosis systems for patients who suffered from epileptic seizures. This paper presents an EEG classification strategy for short-term epilepsy prognosis, using software for Brain-Computer Interface (BCI) systems. A training scenario is presented, where significant features are extracted and a classification algorithm is trained. The training procedure extracts knowledge in terms of a classification model, which is employed in a real-time testing. For the training of the classification scenario a five-classes dataset of EEG signals is employed in which two-classes have been recorded extracranially and the rest three intracranially including one class with epileptic seizure activity and two classes with seizure-free signals. Promising quantitative results are reported.
- Published
- 2017
141. Wavelet Based Classification of Epileptic Seizures in EEG Signals
- Author
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Alexandros T. Tzallas, Nikolaos Giannakeas, Spyridon Konitsiotis, Markos G. Tsipouras, Katerina D. Tzimourta, and Loukas G. Astrakas
- Subjects
Discrete wavelet transform ,education.field_of_study ,medicine.diagnostic_test ,Computer science ,business.industry ,Speech recognition ,Feature vector ,Feature extraction ,Population ,Pattern recognition ,02 engineering and technology ,Electroencephalography ,medicine.disease ,Support vector machine ,03 medical and health sciences ,Epilepsy ,0302 clinical medicine ,Wavelet ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,020201 artificial intelligence & image processing ,Artificial intelligence ,education ,business ,030217 neurology & neurosurgery - Abstract
Epilepsy is a chronic neurological disorder characterized by recurrent, sudden discharges of cerebral neurons, called seizures. Seizures are not always clearly defined and have extremely varied morphologies. Neurophysiologists are not always able to discriminate seizures, especially in long-term EEG datasets. Affecting 1% of the worlds population with 1/3 of the epileptic patients not corresponding to anti-epileptic medication, epilepsy is constantly under the microscope and systems for automated detection of seizures are thoroughly examined. In this paper, a method for automated detection of epileptic activity is presented. The Discrete Wavelet Transform (DWT) is used to decompose the EEG recordings in several subbands and five features are extracted from the wavelet coefficients creating a set of features. The extracted feature vector is used to train a Support Vector Machine (SVM) classifier. Five classification problems are addressed, reaching high levels of overall accuracy ranging from 87% to 100%.
- Published
- 2017
142. PWE-094 The severity of steatosis does not influence liver stiffness measurements in patients with non-alcoholic fatty liver disease
- Author
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Michael Yee, E. Goldin, Roberta Forlano, Benjamin H. Mullish, Shahid A. Khan, F Rui, Gaetano Serviddio, Nikolaos Giannakeas, N. Angkathunyakul, Simon D. Taylor-Robinson, Robert D. Goldin, P. Manousou, Markos G. Tsipouras, Alexandros T. Tzallas, Mark Thursz, and Imperial College Healthcare NHS Trust- BRC Funding
- Subjects
medicine.medical_specialty ,Pathology ,medicine.diagnostic_test ,Gastroenterology & Hepatology ,business.industry ,Fatty liver ,1103 Clinical Sciences ,Disease ,Gold standard (test) ,medicine.disease ,Gastroenterology ,Liver stiffness ,Fibrosis ,Internal medicine ,Biopsy ,medicine ,1114 Paediatrics And Reproductive Medicine ,Steatosis ,business ,Transient elastography - Abstract
Introduction Non-invasive characterisation of hepatic steatosis and fibrosis based on Fibroscan elastographyand controlled attenuation paratmeter (CAP) is used widely for diagnosis and follow up in NAFLD. The aim of this study was to assess the correlation between the degree of steatosis as determined by CAP and the degree of fibrosis by liver stiffness measurements unisg the fat and collagen quantitation as gold standard. Method 80 consecutive patients with biopsy confirmed NAFLD and transient elastography with CAP score.Biopsies were digitalized at 2x magnification and then analysed by our automated software.Fat and fibrosis quantitation wereexpressed as percentages of the relative areas of fat and collagen respectively and of tissue. Results Correlation between CAP score and fat% was statistically significant (p=0.002, Rho=0.45). Regression analysis revealed an R2=0.206 (figure 1a). The AUROC foridentifying fat >5% was 0.82(p=0.001, 95%CI=0.71–0.92) with the best cutoff at 250 dB/m (95% sens, 60% specificity).Correlation between liver stiffness and fibrosis quantitation (%) was statistically significant (p 10% in the liver biopsies there was no difference between liverstiffness and fibrosis quantitation in Pearson’s correlation: Rho=0.883 and Rho=0.843 respectively (figure 2). Conclusion Liver stiffness is a reliable noninvasive tool for estimating the severity of fibrosis in NAFLD. The presenceof severe steatosis evaluated by fat quantitation in liver biopsies did not influence liver stiffness measurements. Disclosure of Interest None Declared
- Published
- 2017
143. Wearability Assessment of a Wearable System for Parkinson’s Disease Remote Monitoring Based on a Body Area Network of Sensors
- Author
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Maria Teresa Arredondo, Dimitrios I. Fotiadis, Matteo Pastorino, Giorgios Rigas, Jorge Cancela, Alexandros T. Tzallas, and Markos G. Tsipouras
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Male ,Engineering ,Telemedicine ,Parkinson's disease ,Wearable computer ,Monitoring, Ambulatory ,Telehealth ,lcsh:Chemical technology ,Biochemistry ,compliance ,Article ,Analytical Chemistry ,Computer Communication Networks ,User-Computer Interface ,Patient satisfaction ,Human–computer interaction ,Component (UML) ,Body area network ,Humans ,lcsh:TP1-1185 ,Electrical and Electronic Engineering ,Body Area Network (BAN) ,Instrumentation ,Wearable technology ,remote monitoring ,Aged ,business.industry ,Parkinson Disease ,Equipment Design ,Patient Acceptance of Health Care ,Atomic and Molecular Physics, and Optics ,3. Good health ,Test (assessment) ,Parkinson’s disease ,motor assessment ,Equipment Failure Analysis ,Patient Satisfaction ,Female ,business ,Telecommunications - Abstract
Wearable technologies for health monitoring have become a reality in the last few years. So far, most research studies have focused on assessments of the technical performance of these systems, as well as the validation of the clinical outcomes. Nevertheless, the success in the acceptance of these solutions depends not only on the technical and clinical effectiveness, but on the final user acceptance. In this work the compliance of a telehealth system for the remote monitoring of Parkinson's disease (PD) patients is presented with testing in 32 PD patients. This system, called PERFORM, is based on a Body Area Network (BAN) of sensors which has already been validated both from the technical and clinical point for view. Diverse methodologies (REBA, Borg and CRS scales in combination with a body map) are employed to study the comfort, biomechanical and physiological effects of the system. The test results allow us to conclude that the acceptance of this system is satisfactory with all the levels of effect on each component scoring in the lowest ranges. This study also provided useful insights and guidelines to lead to redesign of the system to improve patient compliance.
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- 2014
144. NeuralGenesis: A software for distributed neural network training
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Nikolaos Giannakeas, Dimitrios G. Tsalikakis, Elena Zaitseva, Ioannis G. Tsoulos, Markos G. Tsipouras, Alexandros T. Tzallas, and Iosif Androulidakis
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060201 languages & linguistics ,business.industry ,Computer science ,Distributed computing ,Search-based software engineering ,06 humanities and the arts ,02 engineering and technology ,computer.software_genre ,Software portability ,Software ,Server ,Middleware ,0602 languages and literature ,Software construction ,Component-based software engineering ,0202 electrical engineering, electronic engineering, information engineering ,Operating system ,020201 artificial intelligence & image processing ,Software system ,business ,computer - Abstract
A software for distributed neural network training is introduced here. The introduced software named NeuralGenesis implements a client — server model for parallel genetic algorithms with custom features such as: an enhanced stopping rule, an advanced mutation scheme and periodical application of a local search procedure. The software is coded in Qt5 for portability reasons and it is freely available for the majority of operating system.
- Published
- 2016
145. Classification of EEG signals using feature creation produced by grammatical evolution
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Markos G. Tsipouras, Ioannis G. Tsoulos, Nikolaos Giannakeas, Iosif Androulidakis, Alexandras T. Tzallas, and Elena Zaitseva
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Computer science ,Physics::Medical Physics ,Feature extraction ,02 engineering and technology ,Electroencephalography ,computer.software_genre ,03 medical and health sciences ,0302 clinical medicine ,Grammatical evolution ,0202 electrical engineering, electronic engineering, information engineering ,medicine ,Feature (machine learning) ,Radial basis function ,Quantitative Biology::Neurons and Cognition ,medicine.diagnostic_test ,business.industry ,Pattern recognition ,Perceptron ,Time–frequency analysis ,ComputingMethodologies_PATTERNRECOGNITION ,Benchmark (computing) ,020201 artificial intelligence & image processing ,Artificial intelligence ,Data mining ,business ,computer ,030217 neurology & neurosurgery - Abstract
A state-of-the-art method based on a grammatical evolution approach is utilized in this study to classify EEG signals. The method is able to construct nonlinear mappings of the original features in order to improve their effectiveness when used as input into artificial intelligence techniques. Several features are initially extracted from the EEG signals which are subsequently used to create the non-linear mappings. Then, a classification stage is applied, using multi-layer perceptron (MLP) and radial basis functions (RBF), to categorize the EEG signals. The proposed method is evaluated using a benchmark epileptic EEG dataset and promising results are reported.
- Published
- 2016
146. A methodology for automated CPA extraction using liver biopsy image analysis and machine learning techniques
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Epameinondas V Tsianos, Alexandros T. Tzallas, Zoe E. Tsianou, Andrew M. Hall, Markos G. Tsipouras, Ioannis G. Tsoulos, Pinelopi Manousou, and Nikolaos Giannakeas
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Biopsy ,Health Informatics ,Machine learning ,computer.software_genre ,Image (mathematics) ,Machine Learning ,03 medical and health sciences ,Automation ,0302 clinical medicine ,Fibrosis ,Liver tissue ,medicine ,Humans ,Cluster analysis ,medicine.diagnostic_test ,business.industry ,Hepatitis C, Chronic ,medicine.disease ,Computer Science Applications ,Clinical Practice ,Statistical classification ,Concordance correlation coefficient ,Liver ,030220 oncology & carcinogenesis ,Liver biopsy ,030211 gastroenterology & hepatology ,Artificial intelligence ,Collagen ,business ,computer ,Software - Abstract
Methodology for collagen proportional area extraction from liver biopsy images.Fully automated, machine-learning based image analysis.Robust methodology, without any threshold-based decisions.Processing low resolutions images without sophisticated equipment.Low processing time. Background and objectiveCollagen proportional area (CPA) extraction in liver biopsy images provides the degree of fibrosis expansion in liver tissue, which is the most characteristic histological alteration in hepatitis C virus (HCV). Assessment of the fibrotic tissue is currently based on semiquantitative staging scores such as Ishak and Metavir. Since its introduction as a fibrotic tissue assessment technique, CPA calculation based on image analysis techniques has proven to be more accurate than semiquantitative scores. However, CPA has yet to reach everyday clinical practice, since the lack of standardized and robust methods for computerized image analysis for CPA assessment have proven to be a major limitation. MethodsThe current work introduces a three-stage fully automated methodology for CPA extraction based on machine learning techniques. Specifically, clustering algorithms have been employed for background-tissue separation, as well as for fibrosis detection in liver tissue regions, in the first and the third stage of the methodology, respectively. Due to the existence of several types of tissue regions in the image (such as blood clots, muscle tissue, structural collagen, etc.), classification algorithms have been employed to identify liver tissue regions and exclude all other non-liver tissue regions from CPA computation. ResultsFor the evaluation of the methodology, 79 liver biopsy images have been employed, obtaining 1.31% mean absolute CPA error, with 0.923 concordance correlation coefficient. ConclusionsThe proposed methodology is designed to (i) avoid manual threshold-based and region selection processes, widely used in similar approaches presented in the literature, and (ii) minimize CPA calculation time.
- Published
- 2016
147. Assessment of Tremor Activity in the Parkinson’s Disease Using a Set of Wearable Sensors
- Author
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George Rigas, Dimitrios I. Fotiadis, Spiros Konitsiotis, Dina Baga, Evanthia E. Tripoliti, Alexandros T. Tzallas, Panagiota Bougia, Sofia Tsouli, and Markos G. Tsipouras
- Subjects
Motor disorder ,medicine.medical_specialty ,Parkinson's disease ,Movement ,Posture ,Monitoring, Ambulatory ,Wearable computer ,Motor symptoms ,Clothing ,Physical medicine and rehabilitation ,Tremor ,medicine ,Humans ,Electrical and Electronic Engineering ,Set (psychology) ,Aged ,business.industry ,Parkinson Disease ,General Medicine ,Postural tremor ,Middle Aged ,medicine.disease ,Control subjects ,Markov Chains ,nervous system diseases ,Computer Science Applications ,Case-Control Studies ,Physical therapy ,business ,Algorithms ,Biotechnology ,Automated method - Abstract
Tremor is the most common motor disorder of Parkinson's disease (PD) and consequently its detection plays a crucial role in the management and treatment of PD patients. The current diagnosis procedure is based on subject-dependent clinical assessment, which has a difficulty in capturing subtle tremor features. In this paper, an automated method for both resting and action/postural tremor assessment is proposed using a set of accelerometers mounted on different patient's body segments. The estimation of tremor type (resting/action postural) and severity is based on features extracted from the acquired signals and hidden Markov models. The method is evaluated using data collected from 23 subjects (18 PD patients and 5 control subjects). The obtained results verified that the proposed method successfully: 1) quantifies tremor severity with 87 % accuracy, 2) discriminates resting from postural tremor, and 3) discriminates tremor from other Parkinsonian motor symptoms during daily activities.
- Published
- 2012
148. The severity of steatosis does not influence liver stiffness measurements in patients with Non-Alcoholic Fatty Liver Disease
- Author
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Simon D. Taylor-Robinson, Robert D. Goldin, Roberta Forlano, Shahid A. Khan, N. Giannakeas, Mark Thursz, M. Yee, Gaetano Serviddio, Markos G. Tsipouras, James Maurice, Benjamin H. Mullish, Alexandros T. Tzallas, E. Goldin, N. Angkathunyakul, and P. Manousou
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medicine.medical_specialty ,Pathology ,Hepatology ,business.industry ,Fatty liver ,Non alcoholic ,Disease ,medicine.disease ,Gastroenterology ,Liver stiffness ,Internal medicine ,Medicine ,In patient ,Steatosis ,business - Published
- 2017
149. Development and validation of an automated system for assessment of liver steatosis and fibrosis in routine histological images in patients with Non-Alcoholic Fatty Liver Disease
- Author
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Roberta Forlano, M. Yee, P. Manousou, Alexandros T. Tzallas, Markos G. Tsipouras, E. Goldin, N. Giannakeas, Gaetano Serviddio, Robert D. Goldin, N. Angkathunyakul, Mark Thursz, and James Maurice
- Subjects
medicine.medical_specialty ,Pathology ,Hepatology ,business.industry ,Fatty liver ,Non alcoholic ,Disease ,medicine.disease ,Gastroenterology ,Liver steatosis ,Fibrosis ,Internal medicine ,medicine ,In patient ,business - Published
- 2017
150. A mobile application for the management and follow-up of patients with Non-Alcoholic Fatty Liver Disease
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Alexandros T. Tzallas, Markos G. Tsipouras, Simon D. Taylor-Robinson, P. Manousou, Mark Thursz, N. Giannakeas, Nikolaos S. Katertsidis, Roberta Forlano, M. Yee, and Benjamin H. Mullish
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medicine.medical_specialty ,Hepatology ,business.industry ,Internal medicine ,Fatty liver ,medicine ,Non alcoholic ,Disease ,medicine.disease ,business ,Gastroenterology - Published
- 2018
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