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Main Authors: Du, Bodong, Liu, Bowen, Yu, Yang, Ding, Xinpeng, Wu, Zhiheng, Wang, Shuning, Nie, Shuo, Liu, Naiming, Chen, Qifeng, Song, Yangqiu, Li, Xiaomeng
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2605.06537
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author Du, Bodong
Liu, Bowen
Yu, Yang
Ding, Xinpeng
Wu, Zhiheng
Wang, Shuning
Nie, Shuo
Liu, Naiming
Chen, Qifeng
Song, Yangqiu
Li, Xiaomeng
author_facet Du, Bodong
Liu, Bowen
Yu, Yang
Ding, Xinpeng
Wu, Zhiheng
Wang, Shuning
Nie, Shuo
Liu, Naiming
Chen, Qifeng
Song, Yangqiu
Li, Xiaomeng
contents Medical multimodal large language models (MLLMs) have advanced image understanding and short-video analysis, but real clinical review often requires full-procedure video understanding. Unlike general long videos, medical procedures contain highly redundant anatomical views, while decisive evidence is temporally sparse, spatially subtle, and context dependent. Existing benchmarks often assume this evidence has already been localized through images, short clips, or pre-segmented videos, leaving the retrieval-before-reasoning problem under-tested. We introduce MedHorizon, an in-the-wild benchmark for long-context medical video understanding. MedHorizon preserves 759 hours of full-length clinical procedures and provides 1,253 evidence-grounded multiple-choice questionsthat jointly evaluate sparse evidence understanding and multi-hop clinical reasoning. Its evidence is extremely sparse, with only 0.166% evidence frames on average, requiring models to search noisy procedural streams before interpreting and aggregating findings. We evaluate representative general-domain, medical-domain, and long-video MLLMs. The best model reaches only 41.1% accuracy, showing that current systems remain far from robust full-procedure understanding. Further analysis yields four key findings: performance does not scale reliably with more frames, evidence retrieval and clinical interpretation remain primary bottlenecks; these bottlenecks are rooted in weak procedural reasoning and attention drift under redundancy, and generic sampling methods only partially balances local detail with global coverage. MedHorizon provides a rigorous testbed for MLLMs that retrieve sparse evidence and reason over complete clinical workflows.
format Preprint
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publishDate 2026
record_format arxiv
spellingShingle MedHorizon: Towards Long-context Medical Video Understanding in the Wild
Du, Bodong
Liu, Bowen
Yu, Yang
Ding, Xinpeng
Wu, Zhiheng
Wang, Shuning
Nie, Shuo
Liu, Naiming
Chen, Qifeng
Song, Yangqiu
Li, Xiaomeng
Computer Vision and Pattern Recognition
Medical multimodal large language models (MLLMs) have advanced image understanding and short-video analysis, but real clinical review often requires full-procedure video understanding. Unlike general long videos, medical procedures contain highly redundant anatomical views, while decisive evidence is temporally sparse, spatially subtle, and context dependent. Existing benchmarks often assume this evidence has already been localized through images, short clips, or pre-segmented videos, leaving the retrieval-before-reasoning problem under-tested. We introduce MedHorizon, an in-the-wild benchmark for long-context medical video understanding. MedHorizon preserves 759 hours of full-length clinical procedures and provides 1,253 evidence-grounded multiple-choice questionsthat jointly evaluate sparse evidence understanding and multi-hop clinical reasoning. Its evidence is extremely sparse, with only 0.166% evidence frames on average, requiring models to search noisy procedural streams before interpreting and aggregating findings. We evaluate representative general-domain, medical-domain, and long-video MLLMs. The best model reaches only 41.1% accuracy, showing that current systems remain far from robust full-procedure understanding. Further analysis yields four key findings: performance does not scale reliably with more frames, evidence retrieval and clinical interpretation remain primary bottlenecks; these bottlenecks are rooted in weak procedural reasoning and attention drift under redundancy, and generic sampling methods only partially balances local detail with global coverage. MedHorizon provides a rigorous testbed for MLLMs that retrieve sparse evidence and reason over complete clinical workflows.
title MedHorizon: Towards Long-context Medical Video Understanding in the Wild
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2605.06537