Current Organizations / Institutes

The organizations/institutes from the scholar's latest article

Previous Organizations / Institutes

The organizations / institutes from the scholar's other articles in the past ten years


Adrian Krenzer has a total of 73 co-authors. Here are the top co-authors by number of shared publications:

  • Frank Puppe

    11 shared publications
  • Wolfram G. Zoller

    Department of Internal Medicine and Gastroenterology, Katharinenhospital, Stuttgart, Germany

    7 shared publications
  • Alexander Hann

    Interventional and Experimental Endoscopy (InExEn), Department of Internal Medicine II, University Hospital Würzburg, Würzburg, Germany

    5 shared publications
  • Daniel Fitting

    Interventional and Experimental Endoscopy (InExEn), Department of Internal Medicine II, University Hospital Würzburg, Würzburg, Germany

    5 shared publications
  • Joel Troya

    University Hospital Würzburg

    4 shared publications
  • Alexander Hann

    Interventional and Experimental Endoscopy (InExEn), Department of Internal Medicine II, University Hospital Würzburg, Würzburg, Germany

    3 shared publications

Latest Publications

  • Open Access

    Weakly supervised anatomical feature learning for cross-dataset ejection fraction estimation from echocardiography videos

    by Adrian Krenzer, Viktoria Wieser, Tobias Friedetzki

    Background: Ejection fraction (EF) is a central measure of cardiac function, but echocardiographic EF assessment remains reader-dependent and sensitive to acquisition quality. Deep learning can automate EF estimation, yet performance measured on a single development dataset may not transfer to data acquired under different imaging and annotation conventions. We investigated whether anatomically constrained weakly supervised learning improves cross-dataset EF estimation. Methods: We propose CAFEx, a contrastive-augmented feature extraction pipeline that combines left ventricular segmentation, echocardiography-specific augmentation, mask-derived anatomical features, and temporal EF regression. The model was trained on EchoNet-Dynamic using video-level EF labels with limited dense annotations for the anatomical component. External evaluation was performed on CAMUS after image harmonization and recalculation of an apical-four-chamber monoplane EF endpoint. Performance was compared with reproduced segmentation-based, direct video-regression, graph-based, transformer-based, and feature-extraction baselines using Dice score, mean absolute error, and coefficient of determination. Results: In the harmonized train-on-EchoNet/test-on-CAMUS benchmark, anatomically constrained models degraded less than direct video-regression baselines. CAFEx achieved 90.73% Dice on CAMUS and improved CAMUS EF prediction over the strongest reproduced feature-extraction baseline, increasing $$R^2$$ from 0.38 to 0.54 and reducing mean absolute EF error from 7.89 to 6.70 percentage points. Poor-quality videos and extreme EF values remained challenging. Conclusions: Weakly supervised EF estimation can benefit from an anatomical bottleneck learned with limited dense annotation. The findings support controlled external validation under explicit image and target harmonization, while further prospective validation, calibration, and quality-control mechanisms are needed before clinical deployment.

  • iMedSTAM: Interactive Segmentation and Tracking Anything in 3D Medical Images and Videos

    by Tobias Friedetzki, Lorenz Haberzettl, Ricarda Buttmann, Frank Puppe, Adrian Krenzer

  • Open Access

    Assessment of nailed connections in existing timber trusses

    by Lars Völlmecke, Adrian Krenzer, Werner Seim

  • Open Access

    Argumentation effect of a chatbot for ethical discussions about autonomous AI scenarios

    by Christian Hauptmann, Adrian Krenzer, Justin Völkel, Frank Puppe

    This paper explores the potential of a German-language chatbot to engage users in argumentative dialogues on ethically sensitive topics. Utilizing an argumentative knowledge graph, the chatbot is equipped to engage in discussions on the ethical implications of autonomous AI systems in hypothetical future scenarios in the fields of medicine, law, and self-driving cars. In a study with 178 student participants, we investigated the chatbot’s argumentation effect—its ability to offer new perspectives, gain user acceptance, and broaden users’ viewpoints on complex issues. The results indicated a substantial argumentation effect, with 13–21% of participants shifting their opinions to more moderate stances after interacting with the chatbot. This shift demonstrates the system’s effectiveness in fostering informed discourse and increasing users’ understanding of AI ethics. While the chatbot was well-received, with users acknowledging the quality of its arguments, we identified opportunities for improvement in its argument recognition capabilities. Despite this, our results indicate the chatbot’s potential as an educational tool in engaging users with the ethical dimensions of AI technology and promoting informed discourse.


  • Open Access

    Argumentation Effect of a Chatbot for Ethical Discussions about Autonomous AI Scenarios

    by Christian Hauptmann, Adrian Krenzer, Justin Völkel, Frank Puppe

    This study presents a German-language AI chatbot adept at fostering argumentative dialogues across various topics. A core component is the Argumentative Knowledge Graph that powers argument understanding and generation. We showcase the Argumentation Effect of our chatbot in a comprehensive user study. This effect is characterized by the chatbot's successful ability to reshape users' attitudes towards ethically challenging topics, such as autonomous AI systems acting as medicine doctors, by imparting novel perspectives and insights. This led to a substantial gain in user knowledge and acceptance, underscoring the transformative role dialogue systems can play in promoting more informed discussions on complex ethical matters. In tandem with this, we introduced a preliminary methodology for advancing the chatbot's Argument Recognition Unit (ARU). By harnessing real-world user arguments and generated samples from an advanced language model, we achieved significant improvements in the confidence and accuracy of argument prediction. In summary, our research demonstrates how an AI chatbot can instigate a powerful Argumentation Effect, reshaping attitudes, widening knowledge, and facilitating informed discourse on ethically charged topics. This is further amplified by improved argument recognition capabilities, opening promising avenues for more effective, and thus more engaging, user-chatbot dialogues.

  • Open Access

    Direct comparison of multiple computer-aided polyp detection systems

    by Joel Troya, Boban Sudarevic, Adrian Krenzer, Michael Banck, Markus Brand, Benjamin M. Walter, Frank Puppe, Wolfram G. Zoller, Alexander Meining, Alexander Hann

    Background and study aims Artificial intelligence (AI)-based systems for computer-aided detection (CADe) of polyps receive regular updates and occasionally offer customizable detection thresholds, both of which impact their performance, but little is known about these effects. This study aimed to compare the performance of different CADe systems on the same benchmark dataset. Methods 101 colonoscopy videos were used as benchmark. Each video frame with a visible polyp was manually annotated with bounding boxes, resulting in 129 705 polyp images. The videos were then analyzed by three different CADe systems, representing five conditions: two versions of GI Genius, Endo-AID with detection Types A and B, and EndoMind, a freely available system. Evaluation included an analysis of sensitivity and false-positive rate, among other metrics. Results Endo-AID detection Type A, the earlier version of GI Genius, and EndoMind detected all 93 polyps. Both the later version of GI Genius and Endo-AID Type B missed 1 polyp. The mean per-frame sensitivities were 50.63 % and 67.85 %, respectively, for the earlier and later versions of GI Genius, 65.60 % and 52.95 %, respectively, for Endo-AID Types A and B, and 60.22 % for EndoMind. Conclusions This study compares the performance of different CADe systems, different updates, and different configuration modes. This might help clinicians to select the most appropriate system for their specific needs.


  • Open Access

    Automated classification of polyps using deep learning architectures and few-shot learning

    by Adrian Krenzer, Stefan Heil, Daniel Fitting, Safa Matti, Wolfram G. Zoller, Alexander Hann, Frank Puppe

    Background: Colorectal cancer is a leading cause of cancer-related deaths worldwide. The best method to prevent CRC is a colonoscopy. However, not all colon polyps have the risk of becoming cancerous. Therefore, polyps are classified using different classification systems. After the classification, further treatment and procedures are based on the classification of the polyp. Nevertheless, classification is not easy. Therefore, we suggest two novel automated classifications system assisting gastroenterologists in classifying polyps based on the NICE and Paris classification. Methods: We build two classification systems. One is classifying polyps based on their shape (Paris). The other classifies polyps based on their texture and surface patterns (NICE). A two-step process for the Paris classification is introduced: First, detecting and cropping the polyp on the image, and secondly, classifying the polyp based on the cropped area with a transformer network. For the NICE classification, we design a few-shot learning algorithm based on the Deep Metric Learning approach. The algorithm creates an embedding space for polyps, which allows classification from a few examples to account for the data scarcity of NICE annotated images in our database. Results: For the Paris classification, we achieve an accuracy of 89.35 %, surpassing all papers in the literature and establishing a new state-of-the-art and baseline accuracy for other publications on a public data set. For the NICE classification, we achieve a competitive accuracy of 81.13 % and demonstrate thereby the viability of the few-shot learning paradigm in polyp classification in data-scarce environments. Additionally, we show different ablations of the algorithms. Finally, we further elaborate on the explainability of the system by showing heat maps of the neural network explaining neural activations. Conclusion: Overall we introduce two polyp classification systems to assist gastroenterologists. We achieve state-of-the-art performance in the Paris classification and demonstrate the viability of the few-shot learning paradigm in the NICE classification, addressing the prevalent data scarcity issues faced in medical machine learning.