Think Twice to See More: Iterative Visual Reasoning in Medical VLMs

Fuente: arXiv
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Autores principales: Chen, Kaitao, Rui, Shaohao, Jiang, Yankai, Wu, Jiamin, Zheng, Qihao, Song, Chunfeng, Wang, Xiaosong, Zhou, Mu, Liu, Mianxin
Formato: Preprint
Publicado: 2025
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author Chen, Kaitao
Rui, Shaohao
Jiang, Yankai
Wu, Jiamin
Zheng, Qihao
Song, Chunfeng
Wang, Xiaosong
Zhou, Mu
Liu, Mianxin
author_facet Chen, Kaitao
Rui, Shaohao
Jiang, Yankai
Wu, Jiamin
Zheng, Qihao
Song, Chunfeng
Wang, Xiaosong
Zhou, Mu
Liu, Mianxin
contents Medical vision-language models (VLMs) excel at image-text understanding but typically rely on a single-pass reasoning that neglects localized visual cues. In clinical practice, however, human experts iteratively scan, focus, and refine the regions of interest before reaching a final diagnosis. To narrow this machine-human perception gap, we introduce ViTAR, a novel VLM framework that emulates the iterative reasoning process of human experts through a cognitive chain of "think-act-rethink-answer". ViTAR treats medical images as interactive objects, enabling models to engage multi-step visual reasoning. To support this approach, we curate a high-quality instruction dataset comprising 1K interactive examples that encode expert-like diagnostic behaviors. In addition, a 16K visual question answering training data has been curated towards fine-grained visual diagnosis. We introduce a two-stage training strategy that begins with supervised fine-tuning to guide cognitive trajectories, followed by the reinforcement learning to optimize decision-making. Extensive evaluations demonstrate that ViTAR outperforms strong state-of-the-art models. Visual attention analysis reveals that from the "think" to "rethink" rounds, ViTAR increasingly anchors visual grounding to clinically critical regions and maintains high attention allocation to visual tokens during reasoning, providing mechanistic insight into its improved performance. These findings demonstrate that embedding expert-style iterative thinking chains into VLMs enhances both performance and trustworthiness of medical AI.
format Preprint
id arxiv_https___arxiv_org_abs_2510_10052
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Think Twice to See More: Iterative Visual Reasoning in Medical VLMs
Chen, Kaitao
Rui, Shaohao
Jiang, Yankai
Wu, Jiamin
Zheng, Qihao
Song, Chunfeng
Wang, Xiaosong
Zhou, Mu
Liu, Mianxin
Computer Vision and Pattern Recognition
Artificial Intelligence
Medical vision-language models (VLMs) excel at image-text understanding but typically rely on a single-pass reasoning that neglects localized visual cues. In clinical practice, however, human experts iteratively scan, focus, and refine the regions of interest before reaching a final diagnosis. To narrow this machine-human perception gap, we introduce ViTAR, a novel VLM framework that emulates the iterative reasoning process of human experts through a cognitive chain of "think-act-rethink-answer". ViTAR treats medical images as interactive objects, enabling models to engage multi-step visual reasoning. To support this approach, we curate a high-quality instruction dataset comprising 1K interactive examples that encode expert-like diagnostic behaviors. In addition, a 16K visual question answering training data has been curated towards fine-grained visual diagnosis. We introduce a two-stage training strategy that begins with supervised fine-tuning to guide cognitive trajectories, followed by the reinforcement learning to optimize decision-making. Extensive evaluations demonstrate that ViTAR outperforms strong state-of-the-art models. Visual attention analysis reveals that from the "think" to "rethink" rounds, ViTAR increasingly anchors visual grounding to clinically critical regions and maintains high attention allocation to visual tokens during reasoning, providing mechanistic insight into its improved performance. These findings demonstrate that embedding expert-style iterative thinking chains into VLMs enhances both performance and trustworthiness of medical AI.
title Think Twice to See More: Iterative Visual Reasoning in Medical VLMs
topic Computer Vision and Pattern Recognition
Artificial Intelligence
url https://arxiv.org/abs/2510.10052