Dimitris Kalatzis

Dr. Dimitris Kalatzis

orcid

Research Focus & Metrics

Academic Career Length

5Years (2022-Present)

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

Representative Publications

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23 February 2022 in Cancers
Verified
Journal Article
Open access
PDF file
Maria Anthi KouriMaria Anthi Kouri
Maria Anthi Kouri
Ellas SpyratouEllas Spyratou
Ellas Spyratou
MKMaria Karnachoriti
Maria Karnachoriti
DKDimitris Kalatzis
Dimitris Kalatzis
NDNikolaos Danias
Nikolaos Danias
Efstathios P. EfstathopoulosEfstathios P. Efstathopoulos
Efstathios P. Efstathopoulos
Accurate in situ diagnosis and optimal surgical removal of a malignancy constitute key elements in reducing cancer-related morbidity and mortality. In surgical oncology, the accurate discrimination between healthy and cancerous tissues is critical for the postoperative care of the patient. Conventional imaging techniques have attempted to serve as adjuvant tools for in situ biopsy and surgery guidance. However, no single imaging modality has been proven sufficient in terms of specificity, sensitivity, multiplexing capacity, spatial and temporal resolution. Moreover, most techniques are unable to provide information regarding the molecular tissue composition. In this review, we highlight the potential of Raman spectroscopy as a spectroscopic technique with high detection sensitivity and spatial resolution for distinguishing healthy from malignant margins in microscopic scale and in real time. A Raman spectrum constitutes an intrinsic “molecular finger-print” of the tissue and any biochemical alteration related to inflammatory or cancerous tissue state is reflected on its Raman spectral fingerprint. Nowadays, advanced Raman systems coupled with modern instrumentation devices and machine learning methods are entering the clinical arena as adjunct tools towards personalized and optimized efficacy in surgical oncology.

4 December 2025 in Electronics
Verified
Journal Article
Open access
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IGIoannis Givisis
Ioannis Givisis
DKDimitris Kalatzis
Dimitris Kalatzis
Christos E. ChristakisChristos E. Christakis
Christos E. Christakis
YKYiannis Kiouvrekis
Yiannis Kiouvrekis
This study presents a comparative evaluation of state-of-the-art Machine Learning (ML) and Explainable Artificial Intelligence (XAI) methods, specifically SHAP and LIME, for predicting electromagnetic field (EMF) strength in urban environments. Using more than 19,000 in situ EMF measurements across Catalonia, Spain, combined with high-resolution geospatial features such as building height, built-up volume, and population density, six ML algorithms were trained and assessed over 50 randomized train–test splits. The k-Nearest Neighbors (kNN) model achieved the highest predictive accuracy (RMSE = 0.623), followed by XGBoost (RMSE = 0.711) and LightGBM (RMSE = 0.717). Explainability analysis showed that SHAP consistently identified built-up volume, building height, degree of urbanization, and population density as the dominant global predictors of EMF strength, whereas LIME revealed that degree of urbanization, population density, and building height were the most influential at the local (micro-scale) level. The results demonstrate that integrating interpretable ML frameworks with enriched geospatial datasets improves both predictive performance and transparency in EMF exposure modeling, supporting data-driven urban planning and public health assessment.

27 April 2023 in Optics
Verified
Journal Article
Open access
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DKDimitris Kalatzis
Dimitris Kalatzis
Ellas SpyratouEllas Spyratou
Ellas Spyratou
MKMaria Karnachoriti
Maria Karnachoriti
Maria Anthi KouriMaria Anthi Kouri
Maria Anthi Kouri
SOSpyros Orfanoudakis
Spyros Orfanoudakis
Efstathios P. EfstathopoulosEfstathios P. Efstathopoulos
Efstathios P. Efstathopoulos
Advanced Raman spectroscopy (RS) systems have gained new interest in the field of medicine as an emerging tool for in vivo tissue discrimination. The coupling of RS with artificial intelligence (AI) algorithms has given a boost to RS to analyze spectral data in real time with high specificity and sensitivity. However, limitations are still encountered due to the large amount of clinical data which are required for the pre-training process of AI algorithms. In this study, human healthy and cancerous colon specimens were surgically resected from different sites of the ascending colon and analyzed by RS. Two transfer learning models, the one-dimensional convolutional neural network (1D-CNN) and the 1D–ResNet transfer learning (1D-ResNet) network, were developed and evaluated using a Raman open database for the pre-training process which consisted of spectra of pathogen bacteria. According to the results, both models achieved high accuracy of 88% for healthy/cancerous tissue discrimination by overcoming the limitation of the collection of a large number of spectra for the pre-training process. This gives a boost to RS as an adjuvant tool for real-time biopsy and surgery guidance.

24 November 2023 in Journal of Imaging
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Journal Article
Open access
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DKDimitris Kalatzis
Dimitris Kalatzis
Ellas SpyratouEllas Spyratou
Ellas Spyratou
MKMaria Karnachoriti
Maria Karnachoriti
Maria Anthi KouriMaria Anthi Kouri
Maria Anthi Kouri
ISIoannis Stathopoulos
Ioannis Stathopoulos
Efstathios P. EfstathopoulosEfstathios P. Efstathopoulos
Efstathios P. Efstathopoulos
Raman spectroscopy (RS) techniques are attracting attention in the medical field as a promising tool for real-time biochemical analyses. The integration of artificial intelligence (AI) algorithms with RS has greatly enhanced its ability to accurately classify spectral data in vivo. This combination has opened up new possibilities for precise and efficient analysis in medical applications. In this study, healthy and cancerous specimens from 22 patients who underwent open colorectal surgery were collected. By using these spectral data, we investigate an optimal preprocessing pipeline for statistical analysis using AI techniques. This exploration entails proposing preprocessing methods and algorithms to enhance classification outcomes. The research encompasses a thorough ablation study comparing machine learning and deep learning algorithms toward the advancement of the clinical applicability of RS. The results indicate substantial accuracy improvements using techniques like baseline correction, L2 normalization, filtering, and PCA, yielding an overall accuracy enhancement of 15.8%. In comparing various algorithms, machine learning models, such as XGBoost and Random Forest, demonstrate effectiveness in classifying both normal and abnormal tissues. Similarly, deep learning models, such as 1D-Resnet and particularly the 1D-CNN model, exhibit superior performance in classifying abnormal cases. This research contributes valuable insights into the integration of AI in medical diagnostics and expands the potential of RS methods for achieving accurate malignancy classification.

14 August 2025 in Microplastics
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Journal Article
Open access
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DKDimitris Kalatzis
Dimitris Kalatzis
AKAngeliki Katsafadou
Angeliki Katsafadou
EKEleni I. Katsarou
Eleni I. Katsarou
DCDimitrios C. Chatzopoulos
Dimitrios C. Chatzopoulos
YKYiannis Kiouvrekis
Yiannis Kiouvrekis
Accurate identification of microplastic polymers in marine environments is essential for tracing pollution sources, understanding ecological impacts, and guiding mitigation strategies. This study presents a comprehensive, explainable-AI framework that uses Raman spectroscopy to classify pristine and weathered microplastics versus biological materials. Using a curated spectral library of 78 polymer specimens—including pristine, weathered, and biological materials—we benchmark seven supervised machine learning models (Decision Trees, Random Forest, k-Nearest Neighbours, Neural Networks, LightGBM, XGBoost and Support Vector Machines) without and with Principal Component Analysis for binary classification. Although k-Nearest Neighbours and Support Vector Machines achieved the highest single metric accuracy (82.5%), k NN also recorded the highest recall both with and without PCA, thereby offering the most balanced overall performance. To enhance interpretability, we employed SHapley Additive exPlanations, which revealed chemically meaningful spectral regions (notably near 700 cm−1 and 1080 cm−1) as critical to model predictions. Notably, models trained without Principal Component Analysis provided clearer feature attributions, suggesting improved interpretability in raw spectral space. This pipeline surpasses traditional spectral matching techniques and also delivers transparent insights into classification logic. Our findings can support scalable, real-time deployment of AI-based tools for oceanic microplastic monitoring and environmental policy development.

Verified
Journal Article
Open access
PDF file
Maria Anthi KouriMaria Anthi Kouri
Maria Anthi Kouri
MKMaria Karnachoriti
Maria Karnachoriti
Ellas SpyratouEllas Spyratou
Ellas Spyratou
SOSpyros Orfanoudakis
Spyros Orfanoudakis
DKDimitris Kalatzis
Dimitris Kalatzis
MLMARIA LAMBROPOULOU
MARIA LAMBROPOULOU
Raman spectroscopy has emerged as a powerful tool in medical, biochemical, and biological research with high specificity, sensitivity, and spatial and temporal resolution. Recent advanced Raman systems, such as portable Raman systems and fiber-optic probes, provide the potential for accurate in vivo discrimination between healthy and cancerous tissues. In our study, a portable Raman probe spectrometer was tested in immunosuppressed mice for the in vivo localization of colorectal cancer malignancies from normal tissue margins. The acquired Raman spectra were preprocessed, and principal component analysis (PCA) was performed to facilitate discrimination between malignant and normal tissues and to highlight their biochemical differences using loading plots. A transfer learning model based on a one-dimensional convolutional neural network (1D-CNN) was employed for the Raman spectra data to assess the classification accuracy of Raman spectra in live animals. The 1D-CNN model yielded an 89.9% accuracy and 91.4% precision in tissue classification. Our results contribute to the field of Raman spectroscopy in cancer diagnosis, highlighting its promising role within clinical applications.