Abstract

Magnetic resonance imaging (MRI) method based on deep learning needs large-quantity and high-quality patient-based datasets for pre-training. However, this is a challenge to the clinical applications because it is difficult to obtain a sufficient quantity of patient-based MR datasets due to the limitation of equipment and patient privacy concerns. In this paper, we propose a novel undersampled MRI reconstruction method based on deep learning. This method does not require any pre-training procedures and does not depend on training datasets. The proposed method is inspired by the traditional deep image prior (DIP) framework, and integrates the structure prior and support prior of the target MR image to improve the efficiency of learning. Based on the similarity between the reference image and the target image, the high-resolution reference image obtained in advance is used as the network input, thereby incorporating the structural prior information into network. By taking the coefficient index set of the reference image with large amplitude in the wavelet domain as the known support of the target image, the regularization constraint term is constructed, and the network training is transformed into the optimization process of network parameters. Experimental results show that the proposed method can obtain more accurate reconstructions from undersampled <i>k</i>-space data, and has obvious advantages in preserving tissue features and detailed texture.

Highlights

  • T 为目标图像的已知支撑集, T c 代表 已知支撑集 T 的补集

  • 2) (School of Information Engineering, Minzu University of China, Beijing 10081, China) 3) (School of Physics and Telecommunication Engineering, Yulin Normal University, Yulin 537000, China)

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Summary

LeakyReLU u

P 图 2 参考图像和目标图像的结构相似性及小波域支撑分布: 同一病人的脑部扫描 MR 图像 (a) 和 (b), 对应的小波系数分布 (c) 和 (d). Structural similarity between the reference and target images and support distributions in the wavelet domain: Brain MR I images (a) and (b) from the same patient, and the corresponding wavelet coefficient distributions (c) and (d). T 为目标图像的已知支撑集, T c 代表 已知支撑集 T 的补集. 本文基于 DIP, 提出如式 (1) 所示的目标函 数, 将深度神经网络的训练转化为网络参数的最优 化求解, 通过反复迭代地优化求解获得最优网络参 数. 其中, F 是傅里叶变换, y 是欠采样模板 U 下对应 空间位置处的测量数据, U 代表 U 的补集. 如式 (3) 所示的 k 空间数据矫正算子保证了重建结果与 扫描获取的 k 空间测量数据的完全一致性, 使得重 建误差仅集中于未采样的 k 空间数据. 本文方法采用 U-net 网络架构, 与 DIP 方法 [24] 采用的网络架构相同. 为确保公平对比, 所有方法都使用与零填充重 e 建相应的 k 空间测量数据作为输入, 且本文方法和 r 传统 DIP 方法采用相同的网络架构.

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