arXiv:2409.07757cs.CV2024-09被引 2

针对医学数据少且不断新增类别,提出不确定度引导的增量学习方法。

From Uncertainty to Clarity: Uncertainty-Guided Class-Incremental Learning for Limited Biomedical Samples via Semantic Expansion

  • 用累积熵预测不确定样本,存入记忆库供后续回顾。
  • 通过语义增强使特征分布更紧凑,提升对新类别的泛化能力。
  • 在两个数据集上准确率领先现有方法最高达53.54%,适合小样本医学场景。

真实临床环境中,数据分布随时间演变,持续出现新病种但样本量有限。因此,类增量学习至关重要——模型需在不遗忘旧病识别的前提下学习新类别知识。然而传统深度神经网络在适应新数据时易严重遗忘旧知识,除非从头训练,这带来巨大时间和计算开销。此外,不同疾病的样本量高度不平衡,新病种通常实例极少,导致分类偏差。为此,我们首次提出适用于有限医学样本的类增量学习方法。首先,提出新颖的累积熵预测模块,用于衡量样本不确定性,将最不确定的样本存入记忆库作为模型后期回溯的原型。其次,理论上证明了该模块在度量不确定性上的有效性。进一步,设计细粒度语义扩展模块,通过多种增强手段使特征空间内分布更紧凑,为新类别泛化创造充分空间。同时采用余弦分类器缓解数据不平衡带来的分类偏差。在两个数据集上的四个不平衡数据分布下,本方法性能最优,准确率相比现有最佳方法最高提升53.54%。

原文摘要 · Abstract (English)

In real-world clinical settings, data distributions evolve over time, with a continuous influx of new, limited disease cases. Therefore, class incremental learning is of great significance, i.e., deep learning models are required to learn new class knowledge while maintaining accurate recognition of previous diseases. However, traditional deep neural networks often suffer from severe forgetting of prior knowledge when adapting to new data unless trained from scratch, which undesirably costs much time and computational burden. Additionally, the sample sizes for different diseases can be highly imbalanced, with newly emerging diseases typically having much fewer instances, consequently causing the classification bias. To tackle these challenges, we are the first to propose a class-incremental learning method under limited samples in the biomedical field. First, we propose a novel cumulative entropy prediction module to measure the uncertainty of the samples, of which the most uncertain samples are stored in a memory bank as exemplars for the model's later review. Furthermore, we theoretically demonstrate its effectiveness in measuring uncertainty. Second, we developed a fine-grained semantic expansion module through various augmentations, leading to more compact distributions within the feature space and creating sufficient room for generalization to new classes. Besides, a cosine classifier is utilized to mitigate classification bias caused by imbalanced datasets. Across four imbalanced data distributions over two datasets, our method achieves optimal performance, surpassing state-of-the-art methods by as much as 53.54% in accuracy.

增量学习医学影像小样本语义增强

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