Georgios Petmezas

Dr. Georgios Petmezas

Aristotle University of Thessaloniki (AUTh)
orcid

Research Focus & Metrics

Academic Career Length

6Years (2021-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 January 2021 in Biomedical Signal Processing and Control
Verified
Journal Article
Closed access
Georgios PetmezasGeorgios Petmezas
Georgios Petmezas
KHKostas Haris
Kostas Haris
LSLeandros Stefanopoulos
Leandros Stefanopoulos
VKVassilis Kilintzis
Vassilis Kilintzis
ATAndreas Tzavelis
Andreas Tzavelis
Nicos MaglaverasNicos Maglaveras
Nicos Maglaveras

6 February 2022 in Sensors
Verified
Journal Article
Open access
PDF file
Georgios PetmezasGeorgios Petmezas
Georgios Petmezas
GCGrigorios-Aris Cheimariotis
Grigorios-Aris Cheimariotis
LSLeandros Stefanopoulos
Leandros Stefanopoulos
BRBruno Rocha
Bruno Rocha
Rui Pedro PaivaRui Pedro Paiva
Rui Pedro Paiva
Nicos MaglaverasNicos Maglaveras
Nicos Maglaveras
Respiratory diseases constitute one of the leading causes of death worldwide and directly affect the patient’s quality of life. Early diagnosis and patient monitoring, which conventionally include lung auscultation, are essential for the efficient management of respiratory diseases. Manual lung sound interpretation is a subjective and time-consuming process that requires high medical expertise. The capabilities that deep learning offers could be exploited in order that robust lung sound classification models can be designed. In this paper, we propose a novel hybrid neural model that implements the focal loss (FL) function to deal with training data imbalance. Features initially extracted from short-time Fourier transform (STFT) spectrograms via a convolutional neural network (CNN) are given as input to a long short-term memory (LSTM) network that memorizes the temporal dependencies between data and classifies four types of lung sounds, including normal, crackles, wheezes, and both crackles and wheezes. The model was trained and tested on the ICBHI 2017 Respiratory Sound Database and achieved state-of-the-art results using three different data splitting strategies—namely, sensitivity 47.37%, specificity 82.46%, score 64.92% and accuracy 73.69% for the official 60/40 split, sensitivity 52.78%, specificity 84.26%, score 68.52% and accuracy 76.39% using interpatient 10-fold cross validation, and sensitivity 60.29% and accuracy 74.57% using leave-one-out cross validation.

15 August 2022 in JMIR Medical Informatics
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Journal Article
Open access
Georgios PetmezasGeorgios Petmezas
Georgios Petmezas
LSLeandros Stefanopoulos
Leandros Stefanopoulos
VKVassilis Kilintzis
Vassilis Kilintzis
ATAndreas Tzavelis
Andreas Tzavelis
John A. RogersJohn A. Rogers
John A. Rogers
Nicos MaglaverasNicos Maglaveras
Nicos Maglaveras
Background: Electrocardiogram (ECG) is one of the most common noninvasive diagnostic tools that can provide useful information regarding a patient’s health status. Deep learning (DL) is an area of intense exploration that leads the way in most attempts to create powerful diagnostic models based on physiological signals. Objective: This study aimed to provide a systematic review of DL methods applied to ECG data for various clinical applications. Methods: The PubMed search engine was systematically searched by combining “deep learning” and keywords such as “ecg,” “ekg,” “electrocardiogram,” “electrocardiography,” and “electrocardiology.” Irrelevant articles were excluded from the study after screening titles and abstracts, and the remaining articles were further reviewed. The reasons for article exclusion were manuscripts written in any language other than English, absence of ECG data or DL methods involved in the study, and absence of a quantitative evaluation of the proposed approaches. Results: We identified 230 relevant articles published between January 2020 and December 2021 and grouped them into 6 distinct medical applications, namely, blood pressure estimation, cardiovascular disease diagnosis, ECG analysis, biometric recognition, sleep analysis, and other clinical analyses. We provide a complete account of the state-of-the-art DL strategies per the field of application, as well as major ECG data sources. We also present open research problems, such as the lack of attempts to address the issue of blood pressure variability in training data sets, and point out potential gaps in the design and implementation of DL models. Conclusions: We expect that this review will provide insights into state-of-the-art DL methods applied to ECG data and point to future directions for research on DL to create robust models that can assist medical experts in clinical decision-making.

7 May 2024 in Computers in Biology and Medicine
Verified
Journal Article
Closed access
Georgios PetmezasGeorgios Petmezas
Georgios Petmezas
VPVasileios E. Papageorgiou
Vasileios E. Papageorgiou
VVVasileios Vassilikos
Vasileios Vassilikos
EPEfstathios D Pagourelias
Efstathios D Pagourelias
GTGeorge Tsaklidis
George Tsaklidis
Nicos MaglaverasNicos Maglaveras
Nicos Maglaveras

25 March 2025 in Multimedia Tools and Applications
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Journal Article
Open access
PDF file
Georgios PetmezasGeorgios Petmezas
Georgios Petmezas
VVVazgken Vanian
Vazgken Vanian
KKKonstantinos Konstantoudakis
Konstantinos Konstantoudakis
EAElena E. I. Almaloglou
Elena E. I. Almaloglou
DZDimitris Zarpalas
Dimitris Zarpalas
The proliferation of deepfake technology poses significant challenges due to its potential for misuse in creating highly convincing manipulated videos. Deep learning (DL) techniques have emerged as powerful tools for analyzing and identifying subtle inconsistencies that distinguish genuine content from deepfakes. This paper introduces a novel approach for video deepfake detection that integrates 3D Morphable Models (3DMMs) with a hybrid CNN-LSTM-Transformer model, aimed at enhancing detection accuracy and efficiency. Our model leverages 3DMMs for detailed facial feature extraction, a CNN for fine-grained spatial analysis, an LSTM for short-term temporal dynamics, and a Transformer for capturing long-term dependencies in sequential data. This architecture effectively addresses critical challenges in current detection systems by handling both local and global temporal information. The proposed model employs an identity verification approach, comparing test videos with reference videos containing genuine footage of the individuals. Trained and validated on the VoxCeleb2 dataset, with further testing on three additional datasets, our model demonstrates superior performance to existing state-of-the-art methods, maintaining robustness across different video qualities, compression levels and manipulation types. Additionally, it operates efficiently in time-sensitive scenarios, significantly outperforming existing methods in inference speed. By relying solely on pristine, unmanipulated data for training, our approach enhances adaptability to new and sophisticated manipulations, setting a new benchmark for video deepfake detection technologies. This study not only advances the framework for detecting deepfakes but also underscores its potential for practical deployment in areas critical for digital forensics and media integrity.

16 July 2023 in Computer Methods and Programs in Biomedicine
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Journal Article
Open access
Diogo PessoaDiogo Pessoa
Diogo Pessoa
BRBruno Machado Rocha
Bruno Machado Rocha
CSClaas Strodthoff
Claas Strodthoff
MGMaria Gomes
Maria Gomes
GRGuilherme Rodrigues
Guilherme Rodrigues
RPRui Pedro Paiva
Rui Pedro Paiva
Respiratory diseases are among the most significant causes of morbidity and mortality worldwide, causing substantial strain on society and health systems. Over the last few decades, there has been increasing interest in the automatic analysis of respiratory sounds and electrical impedance tomography (EIT). Nevertheless, no publicly available databases with both respiratory sound and EIT data are available. In this work, we have assembled the first open-access bimodal database focusing on the differential diagnosis of respiratory diseases (BRACETS: Bimodal Repository of Auscultation Coupled with Electrical Impedance Thoracic Signals). It includes simultaneous recordings of single and multi-channel respiratory sounds and EIT. Furthermore, we have proposed several machine learning-based baseline systems for automatically classifying respiratory diseases in six distinct evaluation tasks using respiratory sound and EIT (A1, A2, A3, B1, B2, B3). These tasks included classifying respiratory diseases at sample and subject levels. The performance of the classification models was evaluated using a 5-fold cross-validation scheme (with subject isolation between folds). The resulting database consists of 1097 respiratory sounds and 795 EIT recordings acquired from 78 adult subjects in two countries (Portugal and Greece). In the task of automatically classifying respiratory diseases, the baseline classification models have achieved the following average balanced accuracy: Task A1 - 77.9±13.1%; Task A2 - 51.6±9.7%; Task A3 - 38.6±13.1%; Task B1 - 90.0±22.4%; Task B2 - 61.4±11.8%; Task B3 - 50.8±10.6%. The creation of this database and its public release will aid the research community in developing automated methodologies to assess and monitor respiratory function, and it might serve as a benchmark in the field of digital medicine for managing respiratory diseases. Moreover, it could pave the way for creating multi-modal robust approaches for that same purpose.