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arXiv 2101.08196eess.IV
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不完全数据的变分流形学习:在多层动态MRI中的应用

Variational manifold learning from incomplete data: application to multislice dynamic MRI

Qing Zou, Abdul Haseeb Ahmed, Prashant Nagpal, Sarv Priya, Rolf Schulte, Mathews Jacob

摘要:

当前基于深度学习的流形学习算法(如变分自动编码器(VAE))需要完全采样的数据来学习真实世界数据集的概率密度。一旦学会,密度可以用于各种任务,包括数据插补。然而,完全采样的数据往往是不可用的各种问题,包括在这项工作中考虑的动态和高分辨率的MRI数据的恢复。为了克服这个问题,我们引入了一种新的变分方法来学习欠采样数据的流形。VAE使用由潜在向量提供的解码器,这些潜在向量是从使用编码器从完全采样图像估计的条件密度中提取的。由于完全采样的图像在我们的设置中不可用,我们通过参数模型来近似潜向量的条件密度,该参数模型的参数是使用反向传播从欠采样测量中估计的。我们使用的框架联合对齐和恢复多层自由呼吸和非门控心脏MRI数据从高度欠采样的测量。大多数当前的自门控和流形心脏MRI方法考虑从每个切片独立恢复图像;这些方法不能利用数据集中的切片间冗余,并且需要复杂的后处理或手动方法来对齐来自不同切片的图像。相比之下,所提出的方案是能够对齐多切片数据,并利用冗余。实验结果表明,该方案的实用性,在动态成像对齐和重建。

英文摘要:

Current deep learning-based manifold learning algorithms such as the variational autoencoder (VAE) require fully sampled data to learn the probability density of real-world datasets. Once learned, the density can be used for a variety of tasks, including data imputation. However, fully sampled data is often unavailable in a variety of problems, including the recovery of dynamic and high-resolution MRI data considered in this work. To overcome this problem, we introduce a novel variational approach to learn a manifold from undersampled data. The VAE uses a decoder fed by latent vectors, drawn from a conditional density estimated from the fully sampled images using an encoder. Since fully sampled images are not available in our setting, we approximate the conditional density of the latent vectors by a parametric model whose parameters are estimated from the undersampled measurements using back-propagation. We use the framework for the joint alignment and recovery of multislice free breathing and ungated cardiac MRI data from highly undersampled measurements. Most of the current self-gating and manifold cardiac MRI approaches consider the independent recovery of images from each slice; these methods are not capable of exploiting the inter-slice redundancies in the datasets and require sophisticated post-processing or manual approaches to align the images from different slices. By contrast, the proposed scheme is able to align the multislice data and exploit the redundancies. Experimental results demonstrate the utility of the proposed scheme in dynamic imaging alignment and reconstructions.

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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