基于群稀疏理论的乳腺动态对比度增强核磁共振图像联合重建  

Joint reconstruction of breast dynamic contrastenhanced magnetic resonance images with group sparsity method

作　　者：王冠皓 徐军[1] 

机构地区：[1]南京信息工程大学信息与控制学院,南京210044

出　　处：《计算机应用》2014年第11期3304-3308,共5页journal of Computer Applications

基　　金：国家自然科学基金资助项目(61273259);江苏省"六大人才高峰"高层次人才项目(2013-XXRJ-019);江苏省自然科学资助项目(BK20141482)

摘　　要：乳腺在注射造影剂钆喷酸葡胺(Gd-DTPA)后,乳腺核磁共振(MR)图像中恶性肿瘤区域比正常或者良性区域呈现出更加快速和更强的灰度变化,因此动态对比度增强核磁共振成像(DCE-MRI)成为了医生检测和诊断乳腺恶性肿瘤的重要工具。但是DCE-MR图像的快速获取目前仍然是一个难题,为了快速高效地获取这样的DCE-MR图像,根据群稀疏思想和压缩感知(CS)理论,提出了一种结合变密度随机采样的共轭梯度下降方法。该方法首先使用变密度随机采样的方式从图像的局部k-空间(傅立叶系数)数据中获取采样信息,再将传统的基于l1范数的共轭梯度下降算法扩展到l2,1范数以使得改进的共轭梯度下降算法可以对多幅DCE-MR图像同时进行联合重建。实验结果表明:采样率小于40%时,改进的联合重建方法比多测量向量(MMV)算法在重建时间上减少了约30%;变密度随机采样比均匀随机采样在重建准确率上提高了约70%。Dynamic Contrast-Enhanced Magnetic Resonance Imaging（ DCE-MRI） demonstrates that malignant tumors generally show faster and higher levels of enhancement than they are seen in benign or normal tissue, after an intravenous injection of the contrast agent Gd-DTPA, DCE-MRI has played important roles in diagnosis and detecting malignant tumor.However, it is still a challenge on the fast reconstruction of DCE-MR images. Based on the idea of group sparse and the theory of Compressed Sensing（ CS）, a conjugate gradient algorithm combined with variable density random sampling method was employed to get samples from the local k-spaces（ Fourier coefficient） sampling data. Then traditional l1 norm conjugate gradient descent algorithm was extended to l2,1norm to jointly reconstruct multiple DCE-MR images simultaneously. Compared with conventional Multi-Measurement Vector（ MMV） algorithm, the proposed approach yields a faster and more accurate reconstruction result. The experimental results show that when the sampling rate is less than 40%, the joint reconstruction time based on conjugate gradient algorithm almost decreased by 30% compared with the MMV algorithm. In addition, compared with the uniform random sampling, the variable density random sampling method improves the accuracy rate about 70%.

关 键 词：动态对比度增强核磁共振成像 压缩感知 共轭梯度 变密度随机采样 群稀疏 

分 类 号：TN919.8[电子电信—通信与信息系统] TP181[电子电信—信息与通信工程]