基于多级残差U-Net的稀疏SPECT图像重建  

Sparse-view SPECT Image Reconstruction Based on Multilevel-residual U-Net

作　　者：叶文权 李斯 凌捷[1] Ye Wen-quan;Li Si;Ling Jie(School of Computer Science and Technology,Guangdong University of Technology,Guangzhou 510006,China)

机构地区：[1]广东工业大学计算机学院,广东广州510006

出　　处：《广东工业大学学报》2023年第1期61-67,共7页Journal of Guangdong University of Technology

基　　金：国家自然科学基金资助项目(11771464);广东省自然科学基金资助项目(2021A1515012290);中山大学广东省计算科学重点实验室开放基金资助项目(2021007)。

摘　　要：低剂量单光子发射型断层扫描(Single-Photon Emission Computed Tomography,SPECT)能够减少放射性示踪剂对人体的辐射损害,因此其临床应用变得愈发重要。SPECT扫描可通过投影角度稀疏采样实现低剂量成像;若直接对稀疏采样投影数据进行迭代重建,投影角度的缺失将导致重建图像中出现严重的射线伪影。现今主流的临床方法普遍在图像重建优化模型中引入特定的正则项以抑制射线伪影,然而该类方法不具有通用性,并且正则项过度依赖于经验选取。本文提出一种新颖的神经网络结构以学习稀疏采样投影数据与全角度采样投影数据之间的映射关系;通过所提网络结构合成缺失角度的投影数据,来提升重建图像的质量。数值实验表明,相较于传统迭代重建方法,论文重建方法所得图像的结构相似性(Structural Similarity,SSIM)提高了59%,标准均方误差(Normalized Mean-SquareError,NMSE)降低了67%,峰值信噪比(Peak Signal-to-Noise Ratio,PSNR)提高了2.48 dB。因此,所提方法能较好地改善稀疏采样投影数据成像后的图像质量。Low-dose single-photon emission computed tomography(SPECT)imaging can reduce the radiation damage to human bodies caused by radioactive tracers,and hence it is becoming more and more important in clinical practice.In a SPECT system,low-dose imaging can be achieved by acquiring projection data of sparseview.The sparse-view projection data,if directly reconstructed by conventional iterative reconstruction methods,will inevitably lead to severe ray artifacts in the image domain.Existing clinical reconstruction methods usually introduce specific regularization to the optimization model to suppress ray artifacts.However,this type of methods may not adapt to projection data with various dosage,and the form of regularization heavily depends on prior knowledge.A novel neural network architecture is proposed to learn the mapping from the sparse-view projection data to the full-view projection data.The projection data of missing view angle is synthesized by the proposed neural network to improve the quality of reconstructed images.Numerical experiments show that,compared with the traditional iterative reconstruction method,the SSIM of the reconstructed image is increased by 59%,the NMSE is reduced by 67%,and the PSNR is increased by 2.48 dB.Therefore,the proposed method can better improve the image quality of sparse-view projection data.

关 键 词：神经网络 SPECT重建 残差学习 U-Net 

分 类 号：TP391[自动化与计算机技术—计算机应用技术]