cs.CVOct 12, 2026

FOCUS: A Subspecialty Foundation Model for Intraoperative Central Nervous System Pathology

Authors: Xing Liu, Yifan Guo, Hongtai Lv, Lei Lou, Yuyi Tan, Jiang Du, Xijia Zhang, Ming Zhang, +13 more

Organizations: Department of Neuropathology, Beijing Neurosurgical Institute, Capital Medical University, No. 119 South Fourth Ring West Road, Fengtai District, Beijing,100070, P.R.China. · CAS Key Laboratory of Molecular Imaging, Institute of Automation, Chinese Academy of Sciences, No. 95 Zhongguancun East Road, Haidian District, Beijing, 100190, P.R. China. · School of Artificial Intelligence, University of Chinese Academy of Sciences, No. 1 Yanqihu East Road, Huairou District, Beijing, 101408, P.R. China. · Department of Pathology, The First Hospital of Hebei Medical University, No. 89 Donggang Road, Shijiazhuang City, Hebei Province, 050031, P.R. China. · Department of Neurosurgery, The First Hospital of Hebei Medical University, No. 89 Donggang Road, Shijiazhuang City, Hebei Province, 050031, P.R. China. · School of Advanced Interdisciplinary Sciences, University of Chinese Academy of Sciences, No. 1 Yanqihu East Road, Huairou District, Beijing, 101408, P.R. China. · Guangdong Provincial People’s Hospital, No. 106 Zhongshan 2nd Road, Guangzhou, Guangdong Province, 510180, P.R. China. · Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, School of Engineering Medicine, Beihang University, No. 37 Xueyuan Road, Haidian District, Beijing 100191, P.R. China.

Abstract

Intraoperative frozen-section diagnosis of central nervous system (CNS) lesions guides surgical decisions but is challenged by artefacts, diagnostic complexity and time constraints. Most pathology foundation models have limited exposure to CNS frozen tissue. Here we present FOCUS, a subspecialty foundation model pretrained on 27,930 frozen-sections enriched for CNS tissue. FOCUS led 11 internal diagnostic and 12 biomarker-prediction tasks, with mean AUCs of 0.969 and 0.877, respectively, retaining leading performance in temporal and external cohorts. To provide more comprehensive diagnostic information, we further organized ten diagnostic tasks into a WHO-aligned diagnostic hierarchy and separately evaluated FOCUS for lymphoma detection, a critical task for intraoperative surgical decision-making. In reader assessments by six neuropathologists, FOCUS assistance enabled junior readers to approach or exceed unassisted senior readers in hierarchical diagnosis and raised junior readers' lymphoma sensitivity from 81.6% to 94.7%. FOCUS could improve diagnostic accuracy and granularity, inform lymphoma-related resection decisions and provide provisional molecular information. Such capabilities highlight the potential of FOCUS to provide robust, clinically actionable support for intraoperative CNS pathology.

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