arXiv:2512.21769cs.CVcs.LG2025-12

通过结构平衡优化,提升3D掩码自编码器的拓扑建模能力。

BertsWin: Resolving Topological Sparsity in 3D Masked Autoencoders via Component-Balanced Structural Optimization

  • 用Swin窗口实现全三维令牌掩码,保留空间拓扑结构。
  • 相比标准ViT-MAE,语义收敛速度提升5.8倍,训练轮次减少15倍。
  • 适用于3D医学图像重建,尤其适合颞下颌关节等高精度场景。

自监督学习与视觉变压器在2D医学影像中表现优异,但在3D体数据上面临挑战。标准掩码自编码器(MAE)难以捕捉三维空间关系,尤其当预训练时75%的令牌被丢弃。本文提出BertsWin,一种融合BERT式完整令牌掩码与Swin Transformer窗口的混合架构,增强3D自监督预训练中的空间上下文学习。不同于传统MAE仅处理可见区域,BertsWin采用完整的3D令牌网格(含掩码与可见),保持空间拓扑完整性;同时使用单层局部Swin窗口降低ViT的二次复杂度。引入结构优先损失函数,并在锥形束CT的颞下颌关节数据上评估。后续评估包含3D CT扫描的TMJ分割任务。结果表明,通过维持完整的三维拓扑,BertsWin相较于标准ViT-MAE基线,内在加速语义收敛达5.8倍。结合提出的GradientConductor优化器,整个BertsWin框架将达到先进重建保真度所需的训练轮次从660降至44,减少15倍。分析显示,该架构在保持理论计算量(FLOP)与稀疏ViT基线相当的前提下,凭借更快收敛实现总计算资源显著降低。

原文摘要 · Abstract (English)

The application of self-supervised learning (SSL) and Vision Transformers (ViTs) approaches demonstrates promising results in the field of 2D medical imaging, but the use of these methods on 3D volumetric images is fraught with difficulties. Standard Masked Autoencoders (MAE), which are state-of-the-art solution for 2D, have a hard time capturing three-dimensional spatial relationships, especially when 75% of tokens are discarded during pre-training. We propose BertsWin, a hybrid architecture combining full BERT-style token masking using Swin Transformer windows, to enhance spatial context learning in 3D during SSL pre-training. Unlike the classic MAE, which processes only visible areas, BertsWin introduces a complete 3D grid of tokens (masked and visible), preserving the spatial topology. And to smooth out the quadratic complexity of ViT, single-level local Swin windows are used. We introduce a structural priority loss function and evaluate the results of cone beam computed tomography of the temporomandibular joints. The subsequent assessment includes TMJ segmentation on 3D CT scans. We demonstrate that the BertsWin architecture, by maintaining a complete three-dimensional spatial topology, inherently accelerates semantic convergence by a factor of 5.8x compared to standard ViT-MAE baselines. Furthermore, when coupled with our proposed GradientConductor optimizer, the full BertsWin framework achieves a 15-fold reduction in training epochs (44 vs 660) required to reach state-of-the-art reconstruction fidelity. Analysis reveals that BertsWin achieves this acceleration without the computational penalty typically associated with dense volumetric processing. At canonical input resolutions, the architecture maintains theoretical FLOP parity with sparse ViT baselines, resulting in a significant net reduction in total computational resources due to faster convergence.

3D重建自监督学习医学影像Transformer

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