Shanghai Key Lab of Digital Media Processing and Transmission, Shanghai Jiao Tong University, China; MoE Key Lab of Artificial Intelligence, AI Institute, Shanghai Jiao Tong University, China.
Department of Mathematics and Lab for Educational Big Data and Policymaking, Shanghai Normal University, China.
Med Image Anal. 2023 Oct;89:102845. doi: 10.1016/j.media.2023.102845. Epub 2023 May 24.
Self-supervised representation learning (SSL) has achieved remarkable success in its application to natural images while falling behind in performance when applied to whole-slide pathological images (WSIs). This is because the inherent characteristics of WSIs in terms of gigapixel resolution and multiple objects in training patches are fundamentally different from natural images. Directly transferring the state-of-the-art (SOTA) SSL methods designed for natural images to WSIs will inevitably compromise their performance. We present a novel scheme SGCL: Spatial Guided Contrastive Learning, to fully explore the inherent properties of WSIs, leveraging the spatial proximity and multi-object priors for stable self-supervision. Beyond the self-invariance of instance discrimination, we expand and propagate the spatial proximity for the intra-invariance from the same WSI and inter-invariance from different WSIs, as well as propose the spatial-guided multi-cropping for inner-invariance within patches. To adaptively explore such spatial information without supervision, we propose a new loss function and conduct a theoretical analysis to validate it. This novel scheme of SGCL is able to achieve additional improvements over the SOTA pre-training methods on diverse downstream tasks across multiple datasets. Extensive ablation studies have been carried out and visualizations of these results have been presented to aid understanding of the proposed SGCL scheme. As open science, all codes and pre-trained models are available at https://github.com/HHHedo/SGCL.
自监督表示学习 (SSL) 在应用于自然图像方面取得了显著的成功,而在应用于全切片病理图像 (WSI) 时性能却落后。这是因为 WSI 在千兆像素分辨率和训练补丁中的多个对象方面的固有特征与自然图像根本不同。直接将针对自然图像设计的最先进 (SOTA) SSL 方法应用于 WSI,不可避免地会影响其性能。我们提出了一种新的方案 SGCL:空间引导对比学习,以充分利用 WSI 的固有特性,利用空间接近性和多目标先验进行稳定的自监督。除了实例判别自不变性之外,我们还扩展并传播了来自同一 WSI 的内部不变性和来自不同 WSI 的内部不变性的空间接近性,以及提出了用于补丁内内部不变性的空间引导多裁剪。为了自适应地探索这种空间信息而无需监督,我们提出了一种新的损失函数,并进行了理论分析来验证它。与多个数据集上的 SOTA 预训练方法相比,这种新的 SGCL 方案能够在各种下游任务中实现额外的改进。已经进行了广泛的消融研究,并呈现了这些结果的可视化,以帮助理解所提出的 SGCL 方案。作为开放科学,所有代码和预训练模型都可在 https://github.com/HHHedo/SGCL 上获得。
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