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arXiv 2603.21806cs.CV

变换器引导的主动MRI采集中的解剖标记不确定性

Anatomical Token Uncertainty for Transformer-Guided Active MRI Acquisition

Tel Aviv University(特拉维夫大学);University of Cambridge(剑桥大学)

Lev Ayzenberg, Shady Abu-Hussein, Raja Giryes, Hayit Greenspan

AI总结:

本文提出了一种利用预训练医学图像标记器和潜在变换器的主动采样框架,通过量化视觉标记字典表示解剖结构,利用潜在空间的概率分布进行不确定性测量,指导主动采样过程。

摘要:

MRI的完整数据采集本质上是缓慢的,这限制了临床吞吐量并增加了患者不适。压缩感知MRI(CS-MRI)试图通过从欠采样的k空间数据中重建图像来加速采集,需要最优的采样轨迹和高保真的重建模型。在本文中,我们提出了一种新的主动采样框架,利用预训练医学图像标记器和潜在变换器的固有离散结构。通过量化视觉标记字典表示解剖结构,模型在潜在空间上提供了一个明确的概率分布。我们利用该分布推导出通过标记熵的原理性不确定性度量,以指导主动采样过程。我们引入了两种策略来利用这种潜在不确定性:(1)潜在熵选择(LES),将块级标记熵投影到k空间域以识别信息丰富的采样线;(2)基于梯度的熵优化(GEO),通过k空间梯度的总潜在熵损失识别最大不确定性减少区域。我们在fastMRI单coil膝关节和大脑数据集上评估了我们的框架,在×8和×16的加速率下。我们的结果表明,我们的主动策略在感知度量和基于特征的距离上优于最先进的基线。我们的代码可在https://github.com/levayz/TRUST-MRI上获得。

英文摘要:

Full data acquisition in MRI is inherently slow, which limits clinical throughput and increases patient discomfort. Compressed Sensing MRI (CS-MRI) seeks to accelerate acquisition by reconstructing images from under-sampled k-space data, requiring both an optimal sampling trajectory and a high-fidelity reconstruction model. In this work, we propose a novel active sampling framework that leverages the inherent discrete structure of a pretrained medical image tokenizer and a latent transformer. By representing anatomy through a dictionary of quantized visual tokens, the model provides a well-defined probability distribution over the latent space. We utilize this distribution to derive a principled uncertainty measure via token entropy, which guides the active sampling process. We introduce two strategies to exploit this latent uncertainty: (1) Latent Entropy Selection (LES), projecting patch-wise token entropy into the $k$-space domain to identify informative sampling lines, and (2) Gradient-based Entropy Optimization (GEO), which identifies regions of maximum uncertainty reduction via the $k$-space gradient of a total latent entropy loss. We evaluate our framework on the fastMRI singlecoil Knee and Brain datasets at $\times 8$ and $\times 16$ acceleration. Our results demonstrate that our active policies outperform state-of-the-art baselines in perceptual metrics, and feature-based distances. Our code is available at https://github.com/levayz/TRUST-MRI.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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