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home / papers / 2026 / LVLM-Aware Multimodal Retrieval for RAG-Based Medical Diagnosis with General-Purpose Models

LVLM-Aware Multimodal Retrieval for RAG-Based Medical Diagnosis with General-Purpose Models

Paper · 2026 · Nir Mazor and Tom Hope

Summary

Retrieval-augmented large vision-language models (LVLMs) can help interpret clinical images. However, retrievers trained separately from the generator often supply evidence that steers the model toward a wrong diagnosis. The authors propose CLARE (Clinical LVLM-Aware Retrieval), which tunes a multimodal retriever so that the image–caption or image–report pairs it returns actually help the LVLM answer correctly. These pairs come from PubMed literature and hospital records. Training has two stages. First, the reader LVLM is fine-tuned on prompts built from a frozen retriever's results. Then the reader is frozen, and a dual-head retriever is aligned to it with a KL-divergence objective. Only general-purpose backbones and small training sets are used. On medical classification and VQA benchmarks, CLARE approaches heavily pre-trained medical models and beats standard multimodal RAG. The paper also introduces "inconsistent retrieval predictions": queries where different retrieved images lead to conflicting answers. These cases are hard even for models without retrieval, and CLARE improves them noticeably. The work suggests that cheap, generator-aware retrieval tuning could replace costly domain pre-training.

Key points

  • Backbones are general-purpose only: Pixtral and Qwen2-VL as readers and jina-clip as the retriever, compared against the medical LVLM Med-Flamingo. Fine-tuning used as few as 546 samples.
  • Evaluation covers Breast, Derma, Retina, VinDr, BRSET, VQA-RAD, SLAKE and PathVQA. Modalities include ultrasound, fundus, X-ray, CT, dermatoscopy and histopathology.
  • GPT-5.2 judged head-to-head relevance on a 10% subset. Retriever fine-tuning raised mean candidate relevance by 0.17 for both readers.
  • In robustness tests, random retrieval still beat the reader-only baseline. With the query image removed, CLARE exceeded random guessing by +0.32 accuracy and +0.28 F1.
  • An oracle analysis showed that useful candidates are often retrieved but lost among less helpful ones. Using o3 as a reranker did not close this gap and generally underperformed CLARE's logit fusion.

Our summary of the paper, in our own words — not its text. The work belongs to its authors; read it at the links above.

 Institutions

 Fields, topics and concepts

Cite

Cite as Nir Mazor and Tom Hope. 2026. LVLM-Aware Multimodal Retrieval for RAG-Based Medical Diagnosis with General-Purpose Models. Findings of the Association for Computational Linguistics: ACL 2026.

The paper itself, not this page. BibTeX from the library's record of the work. DOI 10.18653/v1/2026.findings-acl.512

@inproceedings{mazor2026lvlm,
  title = {{LVLM-Aware Multimodal Retrieval for RAG-Based Medical Diagnosis with General-Purpose Models}},
  author = {Nir Mazor and Tom Hope},
  booktitle = {Findings of the Association for Computational Linguistics: ACL 2026},
  year = {2026},
  doi = {10.18653/v1/2026.findings-acl.512},
  url = {https://doi.org/10.18653/v1/2026.findings-acl.512}
}

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