Cai N.,Guangdong University of Technology |
Wang S.,Guangdong University of Technology |
Wang S.,CAS Shenzhen Institute of Biomedical and Health Engineering |
Wang S.,Shenzhen Key Laboratory for MRI |
And 3 more authors.
Computational and Mathematical Methods in Medicine | Year: 2013
Compressed sensing (CS) has produced promising results on dynamic cardiac MR imaging by exploiting the sparsity in image series. In this paper, we propose a new method to improve the CS reconstruction for dynamic cardiac MRI based on the theory of structured sparse representation. The proposed method user the PCA subdictionaries for adaptive sparse representation and suppresses the sparse coding noise to obtain good reconstructions. An accelerated iterative shrinkage algorithm is used to solve the optimization problem and achieve a fast convergence rate. Experimental results demonstrate that the proposed method improves the reconstruction quality of dynamic cardiac cine MRI over the state-of-the-art CS method. © 2013 Nian Cai et al.
Cai N.,Guangdong University of Technology |
Xie W.,CAS Shenzhen Institute of Biomedical and Health Engineering |
Xie W.,Shenzhen Key Laboratory for MRI |
Su Z.,Guangdong University of Technology |
And 6 more authors.
Computational and Mathematical Methods in Medicine | Year: 2016
Recently, the sparsity which is implicit in MR images has been successfully exploited for fast MR imaging with incomplete acquisitions. In this paper, two novel algorithms are proposed to solve the sparse parallel MR imaging problem, which consists of l 1 regularization and fidelity terms. The two algorithms combine forward-backward operator splitting and Barzilai-Borwein schemes. Theoretically, the presented algorithms overcome the nondifferentiable property in l 1 regularization term. Meanwhile, they are able to treat a general matrix operator that may not be diagonalized by fast Fourier transform and to ensure that a well-conditioned optimization system of equations is simply solved. In addition, we build connections between the proposed algorithms and the state-of-the-art existing methods and prove their convergence with a constant stepsize in Appendix. Numerical results and comparisons with the advanced methods demonstrate the efficiency of proposed algorithms. © 2016 Nian Cai et al.
Wang F.,Peking University |
Wang F.,Xinxiang Medical University |
Shi Y.,Peking University |
Lu L.,Peking University |
And 12 more authors.
PLoS ONE | Year: 2012
Neurotrophic factors, such as glial cell line-derived neurotrophic factor (GDNF), are promising therapeutic agents for neurodegenerative diseases. However, the application of GDNF to treat these diseases effectively is limited because the blood-brain barrier (BBB) prevents the local delivery of macromolecular therapeutic agents from entering the central nervous system (CNS). Focused ultrasound combined with microbubbles (MBs) using appropriate parameters has been previously demonstrated to be able to open the BBB locally and noninvasively. This study investigated the targeted delivery of GDNF MBs through the BBB by magnetic resonance imaging (MRI)-guided focused ultrasound. Evans Blue extravasation and histological examination were used to determine the optimum focused ultrasound parameters. Enzyme-linked immunosorbent assay was performed to verify the effects of GDNF bound on MBs using a biotin-avidin bridging chemistry method to promote GDNF delivery into the brain. The results showed that GDNF can be delivered locally and noninvasively into the CNS through the BBB using MRI-guided focused ultrasound combined with MBs under optimum parameters. MBs that bind GDNF combined with MRI-guided focused ultrasound may be an effective way of delivering neurotrophic factors directly into the CNS. The method described herein provides a potential means of treating patients with CNS diseases. © 2012 Wang et al.
Zhu Y.,CAS Shenzhen Institute of Biomedical and Health Engineering |
Zhu Y.,Shenzhen Key Laboratory for MRI |
Zhang Q.,Interventional Imaging |
Liu Q.,CAS Shenzhen Institute of Biomedical and Health Engineering |
And 10 more authors.
Magnetic Resonance in Medicine | Year: 2015
Purpose: Long scanning time greatly hinders the widespread application of spin-lattice relaxation in rotating frame (T1ρ) in clinics. In this study, a novel method is proposed to reconstruct the T1ρ-weighted images from undersampled k-space data and hence accelerate the acquisition of T1ρ imaging.Methods: The proposed approach (PANDA-T1ρ) combined the benefit of PCA and dictionary learning when reconstructing image from undersampled data. Specifically, the PCA transform was first used to sparsify the image series along the parameter direction and then the sparsified images were reconstructed by means of dictionary learning and finally solved the images. A variation of PANDA-T1ρ was also developed for the heavy noise case. Numerical simulation and in vivo experiments were carried out with the accelerating factor from 2 to 4 to verify the performance of PANDA-T1ρ.Results: The reconstructed T1ρ maps using the PANDA-T1ρ method were found to be comparable to the reference at all verified acceleration factors. Moreover, the variation exhibited better performance than the original version when the k-space data were contaminated by heavy noise.Conclusion: PANDA-T1ρ can significantly reduce the scanning time of T1ρ by integrating PCA and dictionary learning and provides better parameter estimation than the state-of-Art methods for a fixed acceleration factor. © 2014 Wiley Periodicals, Inc.
Luo C.,Chongqing University of Technology |
Luo C.,CAS Shenzhen Institutes of Advanced Technology |
Luo C.,Shenzhen Key Laboratory for MRI |
Hu X.,CAS Shenzhen Institutes of Advanced Technology |
And 12 more authors.
Asia-Pacific Microwave Conference Proceedings, APMC | Year: 2016
In order to obtain high resolution image of vessel wall of carotid artery, an 8-channel carotid coil is fabricated for 3T magnetic resonance imaging in this study. The phantom experiments and in-vivo studies are implemented in order to validate the performance of the fabricated 8-channel carotid coil. The high resolution images are obtained with the fabricated 8-channel carotid coil in clinical examination for in vivo experiment, showing its potential for the clinical diagnosis. © 2015 IEEE.
Zhang Q.,Zhejiang University |
Zhang Q.,CAS Shenzhen Institute of Biomedical and Health Engineering |
Zhang Q.,Shenzhen Key Laboratory for MRI
Proceedings - 2014 7th International Conference on BioMedical Engineering and Informatics, BMEI 2014 | Year: 2014
A fast algorithm is proposed to choose the optimal port-combination for the next generation non-phased array coil. This kind of coil is so promising and scalable that it would mimic any known phased array coil at the cost of a combinatorial optimization problem. The raw data of signal and noise are respectively collected using a Siemens Trio 3T scanner according to the Kellman-McVeigh method. The B1 maps are acquired by the double-angle method. The object is to find the optimal port-combination which results in a high flip angle-to-SAR (specific absorption rate) ratio and SNR in the central region of coronal FOV. The number of feasible solutions to this combinatorial optimization problem raises fast with respect to the port number. Based on the positive definiteness of the noise covariance matrices, the updated Cholesky factorization is employed to accelerate the computation of SNR scaled images in the Roemer's optimal reconstruction. Numerical results show that this algorithm is much faster than the direct-inverse algorithm. © 2014 IEEE.
Zhang Q.F.,Zhejiang University |
Zhang Q.F.,CAS Shenzhen Institute of Biomedical and Health Engineering |
Zhang Q.F.,Xingaoyi magnetism company |
Yang X.,CAS Shenzhen Institute of Biomedical and Health Engineering |
And 3 more authors.
Applied Mechanics and Materials | Year: 2014
The performance of the multicoil shimming is much better than that of the spherical harmonic coils in many aspects. The diameters and locations of the multicoil are optimized for the B0 shimming of the third order spherical harmonic field. And then every independent coil is decomposed into two series coils to take full advantage of a limited number of shim current supplies. The performance is improved by 16.7% when quantified by the surface root mean square. © (2014) Trans Tech Publications, Switzerland.
Peng X.,CAS Shenzhen Institute of Biomedical and Health Engineering |
Peng X.,The Interdisciplinary Center |
Peng X.,Shenzhen Key Laboratory for MRI |
Liu X.,CAS Shenzhen Institute of Biomedical and Health Engineering |
And 7 more authors.
Medical Engineering and Physics | Year: 2014
T2 mapping is a powerful noninvasive technique providing quantitative biological information of the inherent tissue properties. However, its clinical usage is limited due to the relative long scanning time. This paper proposed a novel model-based method to address this problem. Typically, we directly estimated the relaxation values from undersampled k-space data by exploiting the sparse property of proton density and T2 map in a penalized maximum likelihood formulation. An alternating minimization approach was presented to estimate the relaxation maps separately. Both numerical phantom and in vivo experiment dataset were used to demonstrate the performance of the proposed method. We showed that the proposed method outperformed the state-of-the-art techniques in terms of detail preservation and artifact suppression with various reduction factors and in both moderate and heavy noise circumstances. The superior reconstruction performance validated its promising potential in fast T2 mapping applications. © 2014 IPEM.