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About RationAI

Born at Masaryk University, RationAI is a multidisciplinary research group bridging the gap between advanced computer science and clinical medicine. We specialize in transforming "black box" algorithms into Explainable AI (XAI), creating a collaborative ecosystem where data scientists and medical experts can work in lockstep. By integrating automated traceability, robust visualization, and validation metrics co-designed with clinicians, we ensure that every AI-driven insight is transparent, trustworthy, and ready for the high-stakes world of biomedicine. At RationAI, we don't just build powerful models, we build the trust necessary to bring them into the lab and the clinic.

Our vision

We aren't just developing AI models, we’re teaching them to speak our language. Our focus is on creating Explainable AI (XAI) that transforms "black box" algorithms into transparent, collaborative partners for scientists and doctors.

Digital Pathology

Our main directions contains development of methods for detection of various types of cancerous tissue using cutting-edge deep learning techniques. The system is modular and allows rapid prototyping of new deep learning methods for WSI.

Explainability

We focus on develop cutting-edge AI methods and an appropriate environment that will maximally support cooperation between domain experts and computer science specialists with a focus on explaining the behavior of these AI methods (explainable AI, XAI).

Precision Interfaces

Because not everyone is a computer science expert, we are designing advanced UIs tailored for "normal people", transforming raw output of our machine learning models, to more visually understandable shape which can be used to showcase results.

The Feedback Loop

Thanks to pathologist who cooperate with us and are using our technology. We are able to continuously and iteratively refine our models and UIs, based on their direct critiques and insights.

Regulatory Excellence (IVDR)

We provide the validation evidence required for regulatory compliance, specifically the In Vitro Diagnostic Regulation (EU) 2017/746, by generating trusted data and AI method provenance.

Secure Scaling & FAIRness

To protect large-scale multimodal health data, we implement FAIRness support and develop federated machine learning methods that ensure insights remain clear while data stays decentralized and secure.

Software

Hugging Face (follow us)

Explore our other projects (GitHub)

Publications

Explaining Digital Pathology Models Via Clustering Activations.
A. Bajger, J. Obdržálek, V. Kůr, R. Nenutil, P. Holub, V. Musil, T. Brázdil
IEEE 23rd International Symposium on Biomedical Imaging, ISBI. IEEE, 2026.
https://doi.org/10.1109/ISBI61048.2026.11515782

Weakly Supervised Multicenter Nancy Index Scoring in Ulcerative Colitis Using Foundation Models
A. Kukučka, O. Fabián, V. Musil, T. Brázdil
arXiv preprint arXiv:2604.23706, 2026.
https://arxiv.org/abs/2604.23706

LSP-DETR: Efficient and Scalable Nuclei Segmentation in Whole Slide Images
M. Pekár, V. Musil, R. Nenutil, P. Holub, T. Brázdil
arXiv preprint arXiv:2601.03163, 2026.
https://arxiv.org/abs/2601.03163

Older publications

From Slides to AI-Ready Maps: Standardized Multi-Layer Tissue Maps as Metadata for Artificial Intelligence in Digital Pathology
G. Fiala, M. Plass, R. Harb, P. Regitnig, K. Skok, W. Al Zoughbi, C. Zerner, P. Torke, M. Kargl, H. Müller, T. Brázdil, M. Gallo, J. Kubín, R. Stoklasa, R. Nenutil, N. Zerbe, A. Holzinger, P. Holub
Artificial Intelligence in Medicine, vol. 174. Elsevier Science BV, 2026. ISSN 0933-3657.
https://doi.org/10.1016/j.artmed.2026.103368

Model for Ki-67 Proliferation Index Prediction, Trained End-to-End on Routine Diagnostic Data
A. Kukučka, J. Obdržálek, V. Musil, R. Nenutil, P. Holub, T. Brázdil
medRxiv, preprint 2025.06.26.25330333, 2025.
https://doi.org/10.1101/2025.06.26.25330333

Beyond Occlusion: In Search for Near Real-Time Explainability of CNN-Based Prostate Cancer Classification
M. Krebs, J. Obdržálek, V. Musil and T. Brázdil
IEEE 22nd International Symposium on Biomedical Imaging, ISBI. IEEE, 2025
https://doi.org/10.1109/ISBI60581.2025.10980802

LLEXICORP: End-user Explainability of Convolutional Neural Networks
V. Kůr, A. Bajger, A. Kukučka, M. Hradil, V. Musil, T. Brázdil
arXiv preprint arXiv:2511.02720, 2025.
https://arxiv.org/abs/2511.02720

Privacy Risks of Whole-Slide Image Sharing in Digital Pathology
P. Holub, H. Müller, T. Bíl, L. Pireddu, M. Plass, F. Prasser, I. Schlünder, K. Zatloukal, R. Nenutil, T. Brázdil
Nature Communications, vol. 14, article 2577. Nature Portfolio, 2023. ISSN 2041-1723.
https://doi.org/10.1038/s41467-023-37991-y

Shedding Light on the Black Box of a Neural Network Used to Detect Prostate Cancer in Whole Slide Images by Occlusion-Based Explainability
M. Gallo, V. Krajňanský, R. Nenutil, P. Holub, T. Brázdil
New Biotechnology, vol. 78, pp. 52–67. Elsevier, 2023. ISSN 1871-6784.
https://doi.org/10.1016/j.nbt.2023.09.008

xOpat: eXplainable Open Pathology Analysis Tool
J. Horák, K. Furmanová, B. Kozlíková, T. Brázdil, P. Holub, M. Kačenga, M. Gallo, R. Nenutil, J. Byška, V. Rusňák
Computer Graphics Forum, vol. 42, no. 3, pp. 63–73. Wiley, 2023. ISSN 0167-7055.
https://doi.org/10.1111/cgf.14812

Automated Annotations of Epithelial Cells and Stroma in Hematoxylin–Eosin-Stained Whole-Slide Images Using Cytokeratin Re-Staining
T. Brázdil, M. Gallo, R. Nenutil, A. Kubanda, M. Toufar, P. Holub
The Journal of Pathology: Clinical Research, vol. 8, no. 2, pp. 129–142. Wiley, 2022. ISSN 2056-4538.
https://doi.org/10.1002/cjp2.249

Projects

The people behind RationAI

Founders

https://www.muni.cz/en/people/4074-tomas-brazdil

doc. RNDr. Tomáš Brázdil, Ph.D., MBA

https://www.muni.cz/en/people/3248-petr-holub

doc. RNDr. Petr Holub, Ph.D.

https://www.muni.cz/en/people/33391-rudolf-nenutil

MUDr. Rudolf Nenutil, CSc.

Leaders

https://www.muni.cz/en/people/172454-karel-stepka

Mgr. Karel Štěpka, Ph.D.

https://www.muni.cz/en/people/1552-jan-obdrzalek

doc. Mgr. Jan Obdržálek, PhD.

https://www.muni.cz/en/people/3545-lukas-hejtmanek

RNDr. Lukáš Hejtmánek, Ph.D.

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Mgr. Jiří Horák

We cooperate with following institutions

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