MC-CXR: A Multi-Context Chest X-ray Benchmark for Context-Induced Disruption in Vision-Language Models

Junhyeok Lee, Songsoo Kim, Kyu Sung Choi


Abstract
Vision–language models (VLMs) are increasingly used in clinical pipelines where a chest X-ray is interpreted alongside retrieved reports, preliminary notes, or prior imaging. Existing benchmarks measure whether models answer correctly in isolation, but not whether they preserve a correct image-only decision when plausible context conflicts with the image. We introduce Multi-Context Chest X-ray (MC-CXR), a benchmark of 240 cases expanded into 2,522 instances that isolates context-induced disruption through paired perturbation. Each case fixes the current image and target finding while presenting matched reliable and misleading context across text and prior CXR, with visual overlays where available. MC-CXR defines three task families and two paired metrics, the switch-to-wrong rate and the context-aligned error rate. We evaluate ten VLMs spanning open-source general, medical-domain, and closed-source systems. Image-only accuracy is necessary but insufficient. Mean switch rates range from 45.6–78.1% across misleading textual sources and 35.7–61.7% across misleading visual sources. Among switched predictions, 74.6% align with the misleading label for text versus 17.6% for visual context, a 57.0-point gap (95% CI 50.9–62.8). This text–visual asymmetry is observed under the standardized direct-answer protocol. The dataset is available on PhysioNet.
Anthology ID:
2026.findings-emnlp.1681
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
35896–35910
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.1681/
DOI:
10.18653/2026.findings-emnlp.1681
Bibkey:
Cite (ACL):
Junhyeok Lee, Songsoo Kim, and Kyu Sung Choi. 2026. MC-CXR: A Multi-Context Chest X-ray Benchmark for Context-Induced Disruption in Vision-Language Models. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 35896–35910, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
MC-CXR: A Multi-Context Chest X-ray Benchmark for Context-Induced Disruption in Vision-Language Models (Lee et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.1681.pdf