Beyond a Single Frame: Multi-Frame Spatially Grounded Reasoning Across Volumetric MRI

Fuente: arXiv
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Main Authors: Moukheiber, Lama, Yeung, Caleb M., Xue, Haotian, Helbling, Alec, Zhao, Zelin, Chen, Yongxin
Format: Preprint
Published: 2026
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author Moukheiber, Lama
Yeung, Caleb M.
Xue, Haotian
Helbling, Alec
Zhao, Zelin
Chen, Yongxin
author_facet Moukheiber, Lama
Yeung, Caleb M.
Xue, Haotian
Helbling, Alec
Zhao, Zelin
Chen, Yongxin
contents Spatial reasoning and visual grounding are core capabilities for vision-language models (VLMs), yet most medical VLMs produce predictions without transparent reasoning or spatial evidence. Existing benchmarks also evaluate VLMs on isolated 2D images, overlooking the volumetric nature of clinical imaging, where findings can span multiple frames or appear on only a few slices. We introduce Spatially Grounded MRI Visual Question Answering (SGMRI-VQA), a 41,307-pair benchmark for multi-frame, spatially grounded reasoning on volumetric MRI. Built from expert radiologist annotations in the fastMRI+ dataset across brain and knee studies, each QA pair includes a clinician-aligned chain-of-thought trace with frame-indexed bounding box coordinates. Tasks are organized hierarchically across detection, localization, counting/classification, and captioning, requiring models to jointly reason about what is present, where it is, and across which frames it extends. We benchmark 10 VLMs and show that supervised fine-tuning of Qwen3-VL-8B with bounding box supervision consistently improves grounding performance over strong zero-shot baselines, indicating that targeted spatial supervision is an effective path toward grounded clinical reasoning.
format Preprint
id arxiv_https___arxiv_org_abs_2604_15808
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Beyond a Single Frame: Multi-Frame Spatially Grounded Reasoning Across Volumetric MRI
Moukheiber, Lama
Yeung, Caleb M.
Xue, Haotian
Helbling, Alec
Zhao, Zelin
Chen, Yongxin
Computer Vision and Pattern Recognition
Artificial Intelligence
Spatial reasoning and visual grounding are core capabilities for vision-language models (VLMs), yet most medical VLMs produce predictions without transparent reasoning or spatial evidence. Existing benchmarks also evaluate VLMs on isolated 2D images, overlooking the volumetric nature of clinical imaging, where findings can span multiple frames or appear on only a few slices. We introduce Spatially Grounded MRI Visual Question Answering (SGMRI-VQA), a 41,307-pair benchmark for multi-frame, spatially grounded reasoning on volumetric MRI. Built from expert radiologist annotations in the fastMRI+ dataset across brain and knee studies, each QA pair includes a clinician-aligned chain-of-thought trace with frame-indexed bounding box coordinates. Tasks are organized hierarchically across detection, localization, counting/classification, and captioning, requiring models to jointly reason about what is present, where it is, and across which frames it extends. We benchmark 10 VLMs and show that supervised fine-tuning of Qwen3-VL-8B with bounding box supervision consistently improves grounding performance over strong zero-shot baselines, indicating that targeted spatial supervision is an effective path toward grounded clinical reasoning.
title Beyond a Single Frame: Multi-Frame Spatially Grounded Reasoning Across Volumetric MRI
topic Computer Vision and Pattern Recognition
Artificial Intelligence
url https://arxiv.org/abs/2604.15808