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arXiv 2605.09025cs.CVcs.LG

MedFL-Stress: 一种系统性的联邦脑肿瘤分割在跨医院MRI外观偏移下的鲁棒性评估

MedFL-Stress: A Systematic Robustness Evaluation of Federated Brain Tumor Segmentation under Cross-Hospital MRI Appearance Shift

University of Gujrat, Pakistan(瓜尔杰特大学,巴基斯坦)

Kiran Naseer, Naveed Anwer Butt

AI总结:

本文提出MedFL-Stress框架,通过模拟四个医院的MRI外观偏移,评估FedAvg、FedProx和FedBN在不同医院的鲁棒性,发现FedBN在提升最差医院性能方面表现更优。

摘要:

联邦学习使医院能够在不共享患者数据的情况下协同训练分割模型。然而,当前评估协议仅报告平均性能,掩盖了单个医院的失败情况。在临床部署中,一个在某医院持续失败的模型是真正的安全风险,良好的平均分数可能完全掩盖这一问题。我们引入MedFL-Stress,一种受控压力测试框架,暴露这种失败模式。使用BraTS 2020的2D轴向切片,跨四个模拟医院客户端分布,应用梯度MRI外观偏移(伽马对比、尺度偏移和噪声加模糊),反映真实多站点部署中的扫描仪和采集差异。评估了三个联邦基线:FedAvg、FedProx和FedBN。最差医院Dice和医院间差异作为主要指标,而非补充观察。FedAvg获得最高的全局平均Dice(0.8159),但掩盖了其最佳和最差医院之间的0.0850差距。FedBN通过41%(0.0850到0.0503)缩小了这一差距,同时在平均准确性上牺牲不到一半的Dice点(0.8159到0.8109),最差医院的Dice值直接提升3.5点(0.7309到0.7656)。这些发现表明,以鲁棒性为导向的评估协议对于可靠的联邦医疗影像部署至关重要。

英文摘要:

Federated learning enables hospitals to collaboratively train segmentation models without sharing patient data. However, current evaluation protocols report only average performance across clients, masking failures at individual sites. In clinical deployment, a model that fails consistently at one hospital is a real safety risk that a good mean score can hide entirely. We introduce MedFL-Stress, a controlled stress-testing framework that exposes exactly this failure mode. Using 2D axial slices from BraTS 2020 distributed across four simulated hospital clients, we apply graded MRI appearance shifts (gamma contrast, scale-shift, and noise-plus-blur) reflecting scanner and acquisition variability in real multi-site deployments. Three federated baselines are evaluated: FedAvg, FedProx, and FedBN. Worst-hospital Dice and inter-hospital disparity are treated as primary metrics, not supplementary observations. FedAvg achieves the highest global mean Dice (0.8159) but conceals a 0.0850 gap between its best and worst-performing hospital. FedBN closes that gap by 41% (0.0850 to 0.0503) while sacrificing less than half a Dice point in mean accuracy (0.8159 to 0.8109), and the weakest hospital gains 3.5 Dice points outright (0.7309 to 0.7656). These findings demonstrate that robustness-oriented evaluation protocols are essential for reliable federated medical imaging deployment.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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