Visualization of Knowledge Graphs for Explainable Artificial Intelligence

Filipa Serrano, Catia Pesquita

LASIGE, Faculdade de Ciências, Universidade de Lisboa

Motivation

Artificial intelligence (AI) and Machine Learning (ML) have been achieving great results in the biomedical domain. There are valuable deep learning approaches with promising results, but they are “black-box” - their models are uninterpretable by humans. Their lack of explainability severely limits their trustability, specially in sensitive fields, where errors in predictions can have very damaging outcomes. So, there is a growing interest in the field of explainable AI (XAI).


Semantic Explanations emerge as a strategy for explainable AI applications. They use Ontologies and Knowledge Graphs (KG), which model data and represent it in a connected structure. KG and their semantic context can be used for explainable AI in several different ways, such as to encode context, to better organize features, or to provide a semantic layer to explanations.


Our goal is to investigate how visualizations can support XAI for drug therapy recommendations in personalized oncology in the context of the KATY project.



Filter relevant paths in the KG that connect a patient to their predicted drug Design a visualization approach to increase understanding of explanations for AI predictions



Design a visualization approach to increase understanding of explanations for AI predictions

Data




This project is integrated in the european project- Knowledge At the Tip of Your fingers: Clinical Knowledge for Humanity (KATY).

Clinical and biological data, regarding each cancer patient, is being collected by investigators to produce biomedical datasets. This data can then be used by Artificial Intelligence models to make clinical predictions.

The biomedical datasets will also be integrated into a KG that also contains 28 biomedical ontologies that fully cover the domain of the study, and this KG is used to generate the semantic explanations for the AI predictions.

Pipeline


Simulating clinical predictions of personalized drugs for patients based on data from The Cancer Genome Atlas, since the real AI predictions are not available yet.

Generating all the paths that connect a patient to their predicted drug is not feasible, since there is a large amount of information represented in the KG. The challenge is to create SPARQL queries that will reduce the search space, while capturing important paths that provide high quality explanations. This step will include some iterations, by evaluating the resulting paths and rewriting the queries.

After having some candidate explanations, there will be another step of filtering only the best ones, since clinicians cannot afford to analyze multiple different explanations, due to time constraints, as well as the loss in interpretability if multiple explanations are presented.

These explanations can then be evaluated in two ways: Directly, by a domain expert that compares the explanation with bibliographic references. Using a visualization tool, developed for this purpose, for small scale user studies with medical professionals.

Results

  • WebVOWL [1] was chosen as the base visualization tool since it is very complete, and it is open source. It uses a Visual Notation for OWL Ontologies (VOWL), which defines a set of graphical rules that allow a visual representation of KG.


  • For this project, VOWL was extended to support the representation of individuals (represented by ovals) and their relations.


  • The representation of individuals is essential in personalized medicine to distinguish and represent individual patients. The extension of this notation will hopefully be useful for other applications as well.

Authors

Filipa Serrano

LASIGE, Faculdade de Ciências

Catia Pesquita

LASIGE, Faculdade de Ciências

Funding

This work was supported by FCT through the LASIGE Research Unit (UIDB/00408/2020 and UIDP/00408/2020) and by the KATY project which has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 101017453.