用沙普利值分析医学影像分割模型的可解释性,提升临床信任度。
Clinical Interpretability of Deep Learning Segmentation Through Shapley-Derived Agreement and Uncertainty Metrics
- 通过沙普利值量化不同MRI对比度对模型决策的贡献
- 高分病例(Dice>0.6)与临床排序一致性更高
- 排名方差大表明模型不稳定,适合评估模型可靠性
分割是识别器官、组织或病灶等解剖感兴趣区域的基础任务,广泛应用于医学影像辅助诊断。尽管深度学习在医学图像分割中表现优异,但其可解释性仍制约着临床采纳。本文采用对比度级沙普利值,系统扰动输入以评估特征重要性,相比梯度法更贴近临床判断。基于BraTS 2024数据集,对四种MRI对比度和四种模型架构生成沙普利值排名。提出两个指标:模型与‘临床医生’影像排序的一致性,以及跨验证折叠的沙普利值排名方差。性能较高病例(Dice > 0.6)一致性显著增强;沙普利值排名方差越大,模型性能越差(U-Net: r = -0.581)。这些指标为模型可靠性提供了可临床理解的代理指标。
原文摘要 · Abstract (English)
Segmentation is the identification of anatomical regions of interest, such as organs, tissue, and lesions, serving as a fundamental task in computer-aided diagnosis in medical imaging. Although deep learning models have achieved remarkable performance in medical image segmentation, the need for explainability remains critical for ensuring their acceptance and integration in clinical practice, despite the growing research attention in this area. Our approach explored the use of contrast-level Shapley values, a systematic perturbation of model inputs to assess feature importance. While other studies have investigated gradient-based techniques through identifying influential regions in imaging inputs, Shapley values offer a broader, clinically aligned approach, explaining how model performance is fairly attributed to certain imaging contrasts over others. Using the BraTS 2024 dataset, we generated rankings for Shapley values for four MRI contrasts across four model architectures. Two metrics were proposed from the Shapley ranking: agreement between model and ``clinician" imaging ranking, and uncertainty quantified through Shapley ranking variance across cross-validation folds. Higher-performing cases (Dice \textgreater0.6) showed significantly greater agreement with clinical rankings. Increased Shapley ranking variance correlated with decreased performance (U-Net: $r=-0.581$). These metrics provide clinically interpretable proxies for model reliability, helping clinicians better understand state-of-the-art segmentation models.
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