用脉冲神经网络实现低功耗3D脑部MRI配准,精度接近传统模型。
SpikeReg: Energy-Efficient 3D Deformable Medical Image Registration with Spiking Neural Networks

- 基于脉冲神经网络的U-Net架构,通过权重迁移与阈值校准初始化。
- 在OASIS数据集上达Dice 0.7474,能耗降低55.5倍,脉冲率仅12.8%。
- 首次验证稀疏事件驱动计算可胜任高精度医学图像配准,适合边缘部署。
可变形医学图像配准需对齐不同图像中的解剖结构,但3D分辨率下计算开销巨大。脉冲神经网络(SNN)具备稀疏事件驱动计算优势,但尚未系统应用于该任务。本文提出SpikeReg,一种用于3D脑部MRI配准的脉冲U-Net。其通过层间权重迁移与激活百分位阈值校准,从模拟人工神经网络(ANN)教师模型转换而来,并使用结合局部互相关、扩散正则化和脉冲率稀疏性的代理梯度目标进行微调。在OASIS Learn2Reg验证集(19对图像)上,SpikeReg达到Dice分数0.7474±0.032,与原始ANN教师模型(0.7480±0.037,p=0.67)无显著差异,平均脉冲率为12.8%,在事件稀疏的SynOps/MAC代理下,算术能效比相比密集型ANN基线提升55.5倍。此外,研究发现:从教师模型中蒸馏位移会降低性能;以标签Dice损失训练的教师模型无法通过速率编码转换成功迁移。结果表明,密集几何预测可在稀疏事件驱动计算中实现,为类脑医学图像配准开辟新路径。
原文摘要 · Abstract (English)
Deformable medical image registration aligns anatomical structures across images but remains computationally dense at 3D resolution. Spiking neural networks (SNNs) offer sparse event-driven computation, yet have not been systematically studied for deformable medical image registration. We introduce SpikeReg, a spiking U-Net for 3D brain MRI registration. SpikeReg is initialized from an analog ANN registration teacher, converted by layer-wise weight transfer and activation-percentile threshold calibration, and fine-tuned with a surrogate-gradient objective combining local cross-correlation, diffusion regularization, and spike-rate sparsity. On the OASIS Learn2Reg validation split ($19$ image pairs), SpikeReg reaches Dice $0.7474 \pm 0.032$, with no significant paired Dice difference from the ANN teacher ($0.7480 \pm 0.037$, $p = 0.67$), at a $12.8\%$ mean spike rate and a $55.5\times$ projected arithmetic-energy reduction under an event-sparse SynOps/MAC proxy relative to the dense-ANN baseline. We additionally report two negative findings: displacement distillation from the ANN teacher hurts performance, and ANN teachers trained with a label-Dice loss fail to transfer through rate-code conversion. Together these results show that dense geometric prediction can be performed under sparse event-driven computation, opening a path toward neuromorphic medical image registration.
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