提出多图像扩散推理方法,实现高精度异向MRI超分辨率重建。
Likelihood-Separable Diffusion Inference for Multi-Image MRI Super-Resolution
- 利用似然可分离性,分解多视角低分辨数据梯度,无需联合建模
- 在4×/8×/16×异向退化下,显著优于单图超分,达当前最优
- 适用于常规2D多切片扫描,恢复近各向同性解剖结构
扩散模型是当前成像逆问题的最先进方法。其强大的生成能力可逼近先验分布采样,结合已知似然函数,可在不重训练模型的前提下实现后验采样。尽管近期方法提升了后验采样精度,但多数集中于单图逆问题。对于磁共振成像(MRI),常获取多个沿不同轴向的低分辨率互补测量。本文将主流扩散基单图逆问题求解器推广至多图像超分辨率(MISR)MRI。我们证明,基于似然的修正(DPS)可实现跨独立采集测量的精确梯度可分离,从而在不构建联合算子、不修改扩散模型、不增加网络计算量的前提下实现MISR。推导了DPS、DMAP、DPPS及基于扩散的PnP/ADMM的MISR版本,并在4×/8×/16×异向退化下取得显著提升。结果达到异向MRI体积超分辨率的最先进水平,关键在于可从常规2D多切片采集中重建接近各向同性的解剖结构,而这些数据在正交视图中原本高度退化。
原文摘要 · Abstract (English)
Diffusion models are the current state-of-the-art for solving inverse problems in imaging. Their impressive generative capability allows them to approximate sampling from a prior distribution, which alongside a known likelihood function permits posterior sampling without retraining the model. While recent methods have made strides in advancing the accuracy of posterior sampling, the majority focuses on single-image inverse problems. However, for modalities such as magnetic resonance imaging (MRI), it is common to acquire multiple complementary measurements, each low-resolution along a different axis. In this work, we generalize common diffusion-based inverse single-image problem solvers for multi-image super-resolution (MISR) MRI. We show that the DPS likelihood correction allows an exactly-separable gradient decomposition across independently acquired measurements, enabling MISR without constructing a joint operator, modifying the diffusion model, or increasing network function evaluations. We derive MISR versions of DPS, DMAP, DPPS, and diffusion-based PnP/ADMM, and demonstrate substantial gains over SISR across $4\times/8\times/16\times$ anisotropic degradations. Our results achieve state-of-the-art super-resolution of anisotropic MRI volumes and, critically, enable reconstruction of near-isotropic anatomy from routine 2D multi-slice acquisitions, which are otherwise highly degraded in orthogonal views.
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