TCDA-Net: geometry-conditioned differential attention using riesz-inspired multi-scale features for brain tumour classification
摘要
Deep neural networks for medical imaging often lack explicit encoding of intrinsic geometric structure, limiting their sensitivity to tumour boundaries and local intensity variations. This work proposes a geomeTry-conditioned differential attention (TCDA) mechanism for multi-class brain tumour classification from MRI. Unlike conventional attention mechanisms that operate directly on raw feature maps, TCDA constructs attention inputs from structured geometric representations computed from per-channel L2-normalised backbone features via Riesz-transform-inspired multi-scale representations (σ = 1, 2, 4) in the Gaussian scale-space. In this representation, phase captures structural transitions, while amplitude encodes local intensity variations, and both are fused through learnable scale weights. A two-head, channel-wise differential attention formulation is introduced, enabling element-wise modulation of feature channels rather than scalar attention responses. Attention is further conditioned using orientation-aware temperature scaling derived from pooled orientation statistics of the geometric representation, along with a topology-motivated gating signal based on phase zero-crossing density. A residual bypass and stochastic depth (p = 0.1) are incorporated to stabilise optimisation and prevent over-reliance on geometric cues. Experiments on a public brain tumour MRI dataset, together with cross-dataset evaluation on an independent cohort, demonstrate that TCDA consistently improves classification performance across multiple CNN backbones while maintaining robust generalisation. The results indicate that geometry-conditioned differential attention is particularly effective for architectures that benefit from enhanced structural and intensity-aware feature modelling. The code can be reproduced and is available at the following link - https://github.com/Madhav1422/TCDA-Net/tree/main .