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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. Source

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. Source

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. Source

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. Source

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. Source

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