The medical data science group carries out research at the intersection of machine learning and medicine with the ultimate goal of improving diagnosis and treatment outcome to the benefit of the care and wellbeing of patients. As medical and health data is heterogenous and multimodal, our research deals with the advancement of machine learning models and methodologies to address the specific challenges of the medical domain. Specifically, we work in the areas of multimodal data integration, structure detection, and trustworthy (or transparent) models. The challenge lies not only in developing fast, robust and reliable systems but also in systems that are easy to interpret and usable in clinical practice.

### Wie KI helfen kann, angeborene Herzfehler zu erkennen

Julia Vogt writes on netzwoche.ch about how artificial intelligence can help to recognize heart problems in newborns using Echocardiogram videos.

### Pediatric personalized research network Switzerland (SwissPedHealth) – a Joint Pediatric National Data Stream (NDS) accepted for funding

In 2021, SPHN and PHRT jointly launched the call for “National Data Streams” (NDS). After a two-step evaluation procedure, 4 NDS projects have been…

### ETH News: Portrait Article of Dr. Alexander Marx

In this portrait article, Alexander Marx talks about his research at the intersection of Medical Data Science and Causality.

#### Ricards Marcinkevics, Ece Özkan Elsen, Julia E. VogtDebiasing Deep Chest X-Ray Classifiers using Intra- and Post-processing MethodsThe Seventh Machine Learning for Healthcare Conference, MLHC 2022

Abstract

Deep neural networks for image-based screening and computer-aided diagnosis have achieved expert-level performance on various medical imaging modalities, including chest radiographs. Recently, several works have indicated that these state-of-the-art classifiers can be biased with respect to sensitive patient attributes, such as race or gender, leading to growing concerns about demographic disparities and discrimination resulting from algorithmic and model-based decision-making in healthcare. Fair machine learning has focused on mitigating such biases against disadvantaged or marginalised groups, mainly concentrating on tabular data or natural images. This work presents two novel intra-processing techniques based on fine-tuning and pruning an already-trained neural network. These methods are simple yet effective and can be readily applied post hoc in a setting where the protected attribute is unknown during the model development and test time. In addition, we compare several intra- and post-processing approaches applied to debiasing deep chest X-ray classifiers. To the best of our knowledge, this is one of the first efforts studying debiasing methods on chest radiographs. Our results suggest that the considered approaches successfully mitigate biases in fully connected and convolutional neural networks offering stable performance under various settings. The discussed methods can help achieve group fairness of deep medical image classifiers when deploying them in domains with different fairness considerations and constraints.

Authors

Ricards Marcinkevics, Ece Özkan Elsen, Julia E. Vogt

Submitted

The Seventh Machine Learning for Healthcare Conference, MLHC 2022

Date

05.08.2022

#### Ugne Klimiene, Ricards Marcinkevics, Patricia Reis Wolfertstetter, Ece Özkan Elsen, Alyssia Paschke, David Niederberger, Sven Wellmann, Christian Knorr, Julia E VogtMultiview Concept Bottleneck Models Applied to Diagnosing Pediatric AppendicitisOral spotlight at the 2nd Workshop on Interpretable Machine Learning in Healthcare (IMLH), ICML 2022

Abstract

Arguably, interpretability is one of the guiding principles behind the development of machine-learning-based healthcare decision support tools and computer-aided diagnosis systems. There has been a renewed interest in interpretable classification based on high-level concepts, including, among other model classes, the re-exploration of concept bottleneck models. By their nature, medical diagnosis, patient management, and monitoring require the assessment of multiple views and modalities to form a holistic representation of the patient's state. For instance, in ultrasound imaging, a region of interest might be registered from multiple views that are informative about different sets of clinically relevant features. Motivated by this, we extend the classical concept bottleneck model to the multiview classification setting by representation fusion across the views. We apply our multiview concept bottleneck model to the dataset of ultrasound images acquired from a cohort of pediatric patients with suspected appendicitis to predict the disease. The results suggest that auxiliary supervision from the concepts and aggregation across multiple views help develop more accurate and interpretable classifiers.

Authors

Ugne Klimiene, Ricards Marcinkevics, Patricia Reis Wolfertstetter, Ece Özkan Elsen, Alyssia Paschke, David Niederberger, Sven Wellmann, Christian Knorr, Julia E Vogt

Submitted

Oral spotlight at the 2nd Workshop on Interpretable Machine Learning in Healthcare (IMLH), ICML 2022

Date

23.07.2022

#### Ricards Marcinkevics, Pamuditha Silva, Anna-Katharina Hankele, Katharina Csik, Svenja Godbersen, Algera Goga, Lynn Hasenöhrl, Pascale Hirschi, Hasan Kabakci, Mary P LaPierre, Johanna Mayrhofer, Alexandra Title, Xuan Shu, Nouell Baiioud, Sandra Bernal, Laura Dassisti, Mara D Saenz-de-Juano, Meret Schmidhauser, Giulia Silvestrelli, Simon Z Ulbrich, Thea J Ulbrich, Tamara Wyss, Daniel J Stekhoven, Faisal S Al-Quaddoomi, Shuqing Yu, Mascha Binder, Christoph Schultheiss, Claudia Zindel, Christoph Kolling, Jörg Goldhahn, Bahram Kasmapour, Polina Zjablovskaja, Frank Hardung, Anne Richter, Stefan Miltenyi, Luca Piccoli, Sandra Ciesek, Julia E Vogt, Federica Sallusto, Markus Stoffel, Susanne E UlbrichSite-specific Antibody and T Cell Immune Response to Particular Components of SARS-CoV-2The 1st Workshop on Healthcare AI and COVID-19 at ICML 2022

Abstract

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces both B and T cell responses which jointly contribute to effective neutralization and clearance of the virus. Multiple compartments of circulating immune memory to SARS-CoV-2 are not fully understood. We analyzed humoral and T cell immune responses in young convalescent adults with previous asymptomatic SARS-CoV-2 infections or mildly symptomatic COVID-19 disease. We concomitantly measured antibodies in the blood and analyzed SARS-CoV-2-reactive T cell reaction in response to overlapping peptide pools of four viral proteins in peripheral blood mononuclear cells (PBMC). Using statistical and machine learning models, we investigated whether T cell reactivity predicted antibody status. Individuals with previous SARS-CoV-2 infection differed in T cell responses from non-infected individuals. Subjects with previous SARS-CoV-2 infection exhibited CD4+ T cell responses against S1-, N-proteins and CoV-Mix (containing N, M and S protein-derived peptides) that were dominant over CD8+ T cells. At the same time, signals against the M protein were less pronounced. Double positive IL2+/CD154+ and IFN+/TNF+ CD4+ T cells showed the strongest association with antibody titers. T-cell reactivity to CoV-Mix-, S1-, and N-antigens were most strongly associated with humoral immune response, specifically with a compound antibody titer consisting of RBD, S1, S2, and NP. The T cell phenotype of SARS-CoV-2 infected individuals was stable for four months, thereby exceeding antibody decay rates. Our findings demonstrate that mild COVID-19 infections can elicit robust SARS-CoV-2 T-cell reactive immunity against specific components of SARS-CoV-2.

Authors

Ricards Marcinkevics, Pamuditha Silva, Anna-Katharina Hankele, Katharina Csik, Svenja Godbersen, Algera Goga, Lynn Hasenöhrl, Pascale Hirschi, Hasan Kabakci, Mary P LaPierre, Johanna Mayrhofer, Alexandra Title, Xuan Shu, Nouell Baiioud, Sandra Bernal, Laura Dassisti, Mara D Saenz-de-Juano, Meret Schmidhauser, Giulia Silvestrelli, Simon Z Ulbrich, Thea J Ulbrich, Tamara Wyss, Daniel J Stekhoven, Faisal S Al-Quaddoomi, Shuqing Yu, Mascha Binder, Christoph Schultheiss, Claudia Zindel, Christoph Kolling, Jörg Goldhahn, Bahram Kasmapour, Polina Zjablovskaja, Frank Hardung, Anne Richter, Stefan Miltenyi, Luca Piccoli, Sandra Ciesek, Julia E Vogt, Federica Sallusto, Markus Stoffel, Susanne E Ulbrich

Submitted

The 1st Workshop on Healthcare AI and COVID-19 at ICML 2022

Date

22.07.2022

#### Georgia Avarikioti, Alain Ryser, Yuyi Wang, Roger WattenhoferHigh dimensional clustering with r-nets.Proceedings of the AAAI Conference on Artificial Intelligence (Vol. 33, No. 01, pp. 3207-3214).

Abstract

Clustering, a fundamental task in data science and machine learning, groups a set of objects in such a way that objects in the same cluster are closer to each other than to those in other clusters. In this paper, we consider a well-known structure, so-called $r$-nets, which rigorously captures the properties of clustering. We devise algorithms that improve the run-time of approximating $r$-nets in high-dimensional spaces with $\ell_1$ and $\ell_2$ metrics from $\tilde{O}(dn^{2-\Theta(\sqrt{\epsilon})})$ to $\tilde{O}(dn + n^{2-\alpha})$, where $\alpha = \Omega({\epsilon^{1/3}}/{\log(1/\epsilon)})$. These algorithms are also used to improve a framework that provides approximate solutions to other high dimensional distance problems. Using this framework, several important related problems can also be solved efficiently, e.g., $(1+\epsilon)$-approximate $k$th-nearest neighbor distance, $(4+\epsilon)$-approximate Min-Max clustering, $(4+\epsilon)$-approximate $k$-center clustering. In addition, we build an algorithm that $(1+\epsilon)$-approximates greedy permutations in time $\tilde{O}((dn + n^{2-\alpha}) \cdot \log{\Phi})$ where $\Phi$ is the spread of the input. This algorithm is used to $(2+\epsilon)$-approximate $k$-center with the same time complexity.

Authors

Georgia Avarikioti, Alain Ryser, Yuyi Wang, Roger Wattenhofer

Submitted

Proceedings of the AAAI Conference on Artificial Intelligence (Vol. 33, No. 01, pp. 3207-3214).

Date

05.07.2022

#### Alexander Marx, Jonas FischerEstimating Mutual Information via Geodesic kNNProceedings of the SIAM International Conference on Data Mining, SDM 2022

Abstract

Estimating mutual information (MI) between two continuous random variables X and Y allows to capture non-linear dependencies between them, non-parametrically. As such, MI estimation lies at the core of many data science applications. Yet, robustly estimating MI for high-dimensional X and Y is still an open research question. In this paper, we formulate this problem through the lens of manifold learning. That is, we leverage the common assumption that the information of X and Y is captured by a low-dimensional manifold embedded in the observed high-dimensional space and transfer it to MI estimation. As an extension to state-of-the-art kNN estimators, we propose to determine the k-nearest neighbors via geodesic distances on this manifold rather than from the ambient space, which allows us to estimate MI even in the high-dimensional setting. An empirical evaluation of our method, G-KSG, against the state-of-the-art shows that it yields good estimations of MI in classical benchmark and manifold tasks, even for high dimensional datasets, which none of the existing methods can provide.

Authors

Alexander Marx, Jonas Fischer

Submitted

Proceedings of the SIAM International Conference on Data Mining, SDM 2022

Date

30.04.2022