通过双空间不确定性增强医学异常检测,提升模型对病灶的识别能力。
Revisiting Deep Ensemble Uncertainty for Enhanced Medical Anomaly Detection
- 引入特征空间多样性约束机制,避免模型间过度相似
- 结合输入与输出空间不确定性,显著提升异常区域定位精度
- 适用于各类医学影像异常检测任务,尤其适合小样本场景
医学异常检测在病理识别与定位中至关重要。现有方法通常依赖深度集成中的不确定性估计,假设集成模型在正常样本上应达成一致,而在未见异常上产生分歧。然而,这些方法可能在异常上分歧不足或在正常样本上一致性减弱。为此,我们提出D2UE:一种用于医学异常检测的多样化双空间不确定性估计框架。为有效平衡一致与分歧,我们设计了冗余感知排斥(RAR),采用对各向同性缩放和正交变换保持不变的相似性核,显式促进学习器在特征空间中的多样性。此外,为强化异常区域表征,我们提出双空间不确定性(DSU),利用集成在输入空间和输出空间的不确定性。在输入空间中,先计算重构误差相对于输入图像的梯度,再将其与重构输出融合以估计输入不确定性,从而在输出空间分歧较小时仍能有效区分异常。我们在五个不同骨干网络的医学基准上进行了全面评估,实验结果表明该方法优于现有最先进方法,且框架内各组件均具有效性。代码已开源。
原文摘要 · Abstract (English)
Medical anomaly detection (AD) is crucial in pathological identification and localization. Current methods typically rely on uncertainty estimation in deep ensembles to detect anomalies, assuming that ensemble learners should agree on normal samples while exhibiting disagreement on unseen anomalies in the output space. However, these methods may suffer from inadequate disagreement on anomalies or diminished agreement on normal samples. To tackle these issues, we propose D2UE, a Diversified Dual-space Uncertainty Estimation framework for medical anomaly detection. To effectively balance agreement and disagreement for anomaly detection, we propose Redundancy-Aware Repulsion (RAR), which uses a similarity kernel that remains invariant to both isotropic scaling and orthogonal transformations, explicitly promoting diversity in learners' feature space. Moreover, to accentuate anomalous regions, we develop Dual-Space Uncertainty (DSU), which utilizes the ensemble's uncertainty in input and output spaces. In input space, we first calculate gradients of reconstruction error with respect to input images. The gradients are then integrated with reconstruction outputs to estimate uncertainty for inputs, enabling effective anomaly discrimination even when output space disagreement is minimal. We conduct a comprehensive evaluation of five medical benchmarks with different backbones. Experimental results demonstrate the superiority of our method to state-of-the-art methods and the effectiveness of each component in our framework. Our code is available at https://github.com/Rubiscol/D2UE.
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