Case2Flow: Bridging Patient Cases and Guideline Flowcharts through Multimodal Retrieval

Jiale Wei, Yufan Chen, Alexander Jaus, Zdravko Marinov, Julian Friedrich, Simon Reiß, Jens Kleesiek, Rainer Stiefelhagen


Abstract
Medical guidelines encode rich, evidence-based decision logic, yet the specific decision artifact a clinician needs is hard to locate within a guideline, let alone across guidelines covering plausible diseases and treatments. While guideline passages have supported end-to-end question answering, flowcharts remain largely underused in decision support despite their ability to encode actionable clinical pathways. We therefore introduce Case2Flow, a task designed to retrieve the most relevant guideline flowchart for a given patient case from a collection of guideline documents. To support it, we construct FlowAtlas, a curated corpus of 202 flowcharts extracted from 2,080 medical guidelines, together with a pipeline that synthesises 1,911 aligned case-flowchart pairs. Our evaluation of multimodal retrieval methods reveals systematic failure modes, including overreliance on keywords and spurious token-patch matches induced by uninformative background regions in flowcharts. Motivated by this, we propose CRISP, a training-free scoring method that sharpens late-interaction retrieval by suppressing uninformative patches, discounting ambiguous token matches, and incorporating bidirectional query-image alignment. CRISP improves Recall@1 by up to 18.71 percentage points, while a blinded physician assessment on published case narratives provides preliminary feasibility evidence beyond synthetic queries.
Anthology ID:
2026.emnlp-main.2240
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
50976–50992
Language:
URL:
https://aclanthology.org/2026.emnlp-main.2240/
DOI:
Bibkey:
Cite (ACL):
Jiale Wei, Yufan Chen, Alexander Jaus, Zdravko Marinov, Julian Friedrich, Simon Reiß, Jens Kleesiek, and Rainer Stiefelhagen. 2026. Case2Flow: Bridging Patient Cases and Guideline Flowcharts through Multimodal Retrieval. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 50976–50992, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Case2Flow: Bridging Patient Cases and Guideline Flowcharts through Multimodal Retrieval (Wei et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.2240.pdf