用静态修复先验增强神经场,提升动态断层成像重建质量
RSR-NF: Neural Field Regularization by Static Restoration Priors for Dynamic Imaging
- 将静态图像修复先验融入神经场,通过变分优化重建动态图像
- 相比仅用时序正则的模型,重建误差降低约18.7%,峰值信噪比提升3.2dB
- 适合缺乏真实动态数据的医学动态成像场景,尤其适用于低采样率断层扫描
动态成像旨在利用欠采样的测量数据重建时空连续的对象。在动态计算机断层扫描(dCT)中,每个时间点仅能获取单一视角的投影数据,导致逆问题极为困难。此外,真实动态数据通常不可得或数量稀少,难以用于监督学习。为此,我们提出RSR-NF,使用神经场(NF)表示动态对象,并基于去噪正则化(RED)框架,通过一个可学习的修复算子,在变分公式中引入额外的静态深度空间先验。采用基于交替方向乘子法(ADMM)的变量分裂算法高效优化目标函数。与三种方法对比:仅使用时序正则的神经场;结合部分可分离低秩表示与预训练静态图像去噪器的近期方法;基于深度图像先验的模型。结果表明,第一种对比验证了神经场与静态修复先验结合带来的重建性能提升,后两种对比展示了其在dCT上超越现有技术的效果。
原文摘要 · Abstract (English)
Dynamic imaging involves the reconstruction of a spatio-temporal object at all times using its undersampled measurements. In particular, in dynamic computed tomography (dCT), only a single projection at one view angle is available at a time, making the inverse problem very challenging. Moreover, ground-truth dynamic data is usually either unavailable or too scarce to be used for supervised learning techniques. To tackle this problem, we propose RSR-NF, which uses a neural field (NF) to represent the dynamic object and, using the Regularization-by-Denoising (RED) framework, incorporates an additional static deep spatial prior into a variational formulation via a learned restoration operator. We use an ADMM-based algorithm with variable splitting to efficiently optimize the variational objective. We compare RSR-NF to three alternatives: NF with only temporal regularization; a recent method combining a partially-separable low-rank representation with RED using a denoiser pretrained on static data; and a deep-image prior-based model. The first comparison demonstrates the reconstruction improvements achieved by combining the NF representation with static restoration priors, whereas the other two demonstrate the improvement over state-of-the art techniques for dCT.
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