Felix Karl Michael Wagner

PhD in Computer Vision & Medical AI

Advancing AI through federated learning, parameter-efficient fine-tuning, domain adaptation, and privacy-preserving medical imaging systems at the University of Oxford.

About Me

I'm a final-year PhD student at the Department of Engineering Science, University of Oxford, supervised by Professor Konstantinos Kamnitsas. My research sits at the intersection of Computer Vision, Medical Imaging, and Privacy-Preserving AI, with the goal of making AI models more robust, adaptable, and usable in real-world healthcare settings.

Before starting my PhD, I completed both my bachelor’s and master’s degrees in Computer Science at TU Wien, where I explored the combination of symbolic and subsymbolic AI in knowledge graphs. Alongside academia, I gained practical experience as a freelance software engineer and various internships, giving me a solid foundation in building and deploying real systems.

Research Focus

I am passionate about building robust AI systems that can be applied effectively in real-world medical environments. My research has focused on the following areas:

🧠

Medical Imaging AI

Brain MRI segmentation and analysis

πŸ”’

Federated Learning

Privacy-preserving collaborative ML

πŸ”„

Domain Adaptation

Handling distribution shifts

⚑

Foundation Models

Vision-Language model fine-tuning

πŸ“

3D Segmentation

Volumetric medical image analysis

πŸŽ›οΈ

Parameter-Efficient Fine-Tuning

Lightweight model adaptation techniques

🎯 Current Impact

  • 4 papers accepted in 2025 at top-tier venues (CVPR 2025, WACV 2025, AAAI 2025)
  • Honourable Mention as Outstanding Reviewer at MICCAI 2024
  • Novel federated learning frameworks enabling cross-institutional AI collaboration, released as open-source on GitHub to advance reproducible research

News

[06/2025]
DIsoN pre-print on arXiv! πŸŽ‰ Novel decentralized OOD detection framework!
[02/2025]
FΒ³OCUS accepted to CVPR 2025! πŸŽ‰ Federated fine-tuning of vision-language models with optimal layer updating.
[12/2024]
Two papers accepted to AAAI 2025! πŸŽ‰ Multimodal FL & FedPIA on foundation model finetuning.
[10/2024]
FedUniBrain accepted to WACV 2025 as Oral presentation! πŸš€ Multi-disease federated learning for brain MRI.
[10/2024]
Honored as Outstanding Reviewer at MICCAI 2024! πŸ“š
[05/2024]
Co-authored paper on joint learning from MRI databases accepted to MIDL 2024 as Oral! 🎀 Led by Wentian Xu.
[11/2023]
StarAlign presented at MLMI workshop (MICCAI 2023)! ⭐ Post-deployment adaptation via federated learning.
[09/2023]
Started PhD in Computer Vision at University of Oxford! πŸŽ“ Supervised by Prof. Konstantinos Kamnitsas.
[07/2023]
Completed MSc in Computer Science at TU Wien with distinction! πŸ† Thesis on symbolic-subsymbolic AI integration.

Selected Publications

DIsoN figure

DIsoN: Decentralized Isolation Networks for Out-of-Distribution Detection in Medical Imaging

Felix Wagner, Pramit Saha, Harry Anthony, J. Alison Noble, Konstantinos Kamnitsas

Pre-print: Under Review

We introduce DIsoN, a novel decentralized framework for out-of-distribution detection. By comparing test samples with training data without data exchange, DIsoN improves reliability without compromising privacy.

OOD Detection Medical Imaging Decentralized Uncertainty Privacy
focus figure

FΒ³OCUS--Federated Finetuning of Vision-Language Foundation Models with Optimal Client Layer Updating Strategy via Multi-objective Meta-Heuristics

Pramit Saha, Felix Wagner, Divyanshu Mishra, Can Peng, Anshul Thakur, David Clifton, Konstantinos Kamnitsas, J. Alison Noble

IEEE / CVF Computer Vision and Pattern Recognition Conference (CVPR) 2025 Spotlight

A novel layer updating strategy for parameter-efficient finetuning of Vision-Language Foundation Models in resource constrained federated settings. FΒ³OCUS optimizes client-specific layer importance and inter-client layer diversity using multi-objective meta-heuristics.

Federated Learning Foundation Models Vision-Language Parameter-Efficient Fine-Tuning Multi-Modal Meta-Heuristics
FedUniBrain paper figure

Feasibility of Federated Learning from Client Databases with Different Brain Diseases and MRI Modalities

Felix Wagner, Wentian Xu, Pramit Saha, Ziyun Liang, Daniel Whitehouse, David Menon, Virginia Newcombe, Natalia Voets, J. Alison Noble, Konstantinos Kamnitsas

IEEE/CVF Winter Conference on Applications of Computer Vision (WACV) 2025 Oral

We introduce FedUniBrain, demonstrating for the first time that a single federated model can segment multiple brain lesion types from databases with different MRI modalities, all without data exchange between institutions.

Federated Learning Medical Imaging Brain MRI Multi-Task Multi-Modal 3D Segmentation
Post-Deployment Adaptation paper figure

Post-Deployment Adaptation with Access to Source Data via Federated Learning and Source-Target Remote Gradient Alignment

Felix Wagner, Zeju Li, Pramit Saha, Konstantinos Kamnitsas

Machine Learning in Medical Imaging (MLMI 2023) workshop at MICCAI 2023 Oral

We enable deployed models to adapt to new target distributions by accessing training data via federated learning. Our novel gradient alignment algorithm preserves privacy while enabling effective domain adaptation.

Domain Adaptation Federated Learning Gradient Alignment Test-Time Adaptation Medical AI

Why This Matters

In an era where AI is transforming healthcare, my research focuses on making AI in healthcare more safe, private, and reliable across diverse medical institutions. The goal is to enable broader access to advanced AI while protecting patient data and ensuring trust in real-world use.