Wu-fan Chen

Southern Medical University, Shengcheng, Guangdong, China

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Publications (27)4.67 Total impact

  • Lei Zhang · Ming-Hui Zhang · Zhen-Tai Lu · Qian-Jin Feng · Wu-Fan Chen ·
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    ABSTRACT: Objective: We propose a multi-weighted probabilistic atlas to obtain accurate, robust, and reliable segmentation. The local similarity measure is used as the weight to compute the probabilistic atlas, and the distance field is used as the weight to incorporate the locality information of the atlas; the self-similarity is used as the weight to incorporate the local information of target image to refine the probabilistic atlas. Experimental results with brain MRI images showed that the proposed algorithm outperforms the common brain image segmentation methods and achieved a median Dice coefficient of 87.1% on the left hippocampus and 87.6% on the right.
    Nan fang yi ke da xue xue bao = Journal of Southern Medical University 08/2015; 35(8):1143-1148.
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    ABSTRACT: We propose a cross-correlation method for automatic extraction of the pennation angle (PA) of the gastrocnemius (GM) muscle from ultrasound radiofrequency (RF) signals. The ultrasound RF signals of the GM muscles in tension condition from normal subjects and the simulated ultrasound signals were collected. After the starting point of tracking, a fascicle was selected in the reconstructed GM ultrasound image from the RF signals, and the fascicle and deep aponeurosis could be automatically tracked using the cross-correlation algorithm. The lines of the fascicle and deep aponeurosis were then drawn and the PA was calculated. The reproducibility of the proposed method and its consistency with the manual measurement method were tested. The angles of the simulated fascicles were precisely extracted automatically. The difference between the experimental measurement and the theoretical values was less than 1°. The PA measured automatically and manually was 20.48°∓0.47° and 21.49°∓1.79°, respectively. The coefficient of variation (CV) of the two methods was less than 3% and the root-mean square error (RMSE) was less than 1°. Bland-Altman plot showed a good agreement between the proposed automatic method and the manual method. The proposed cross-correlation automatic measurement method can detect the orientation of the fascicle and deep aponeurosis and measure the PA based on ultrasound RF signals with serious speckle noise.
    Nan fang yi ke da xue xue bao = Journal of Southern Medical University 08/2015; 35(8):1116-1121.

  • Chinese Journal of Computers 05/2014; 36(5):1076-1085. DOI:10.3724/SP.J.1016.2013.01076
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    ABSTRACT: Articular cartilage is a solid-fluid biphasic material covering the bony ends of articulating joints. Hydration of articular cartilage is important to joint lubrication and weight-wearing. The aims of this study are to measure the altered hydration behaviour of the proteoglycan-degraded articular cartilage using high-frequency ultrasound and then to investigate the effect of proteoglycan (PG) degradation on cartilage hydration. Twelve porcine patellae with smooth cartilage surface were prepared and evenly divided into two groups: normal group without any enzyme treatment and trypsin group treated with 0.25% trypsin solution for 4h to digest PG in the tissue. After 40-minute exposure to air at room temperature, the specimens were immerged into the physiological saline solution. The dehydration induced hydration behaviour of the specimen was monitored by the high-frequency (25 MHz) ultrasound pulser/receiver (P/R) system. Dynamic strain and equilibrium strain were extracted to quantitatively evaluate the hydration behaviour of the dehydrated cartilage tissues. The hydration progress of the dehydrated cartilage tissue was observed in M-mode ultrasound image indicating that the hydration behaviour of the PG-degraded specimens decreased. The percentage value of the equilibrium strain (1.84 +/- 0.21 %) of the PG-degraded cartilage significantly (p < 0.01) decreased in comparison with healthy cartilage (3.46 +/- 0.49 %). The histological sections demonstrated that almost PG content in the entire cartilage layer was digested by trypsin. Using high-frequency ultrasound, this study found a reduction in the hydration behaviour of the PG-degraded cartilage. The results indicated that the degradation of PG decreased the hydration capability of the dehydrated tissue. This study may provide useful information for further study on changes in the biomechanical property of articular cartilage in osteoarthritis.
    BMC Musculoskeletal Disorders 10/2013; 14(1):289. DOI:10.1186/1471-2474-14-289 · 1.72 Impact Factor
  • Juan Zhang · Zhen-Tai Lu · Vadim Pigrish · Qian-Jin Feng · Wu-Fan Chen ·
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    ABSTRACT: In this paper, we propose a novel intensity-based similarity measure for medical image registration. Traditional intensity-based methods are sensitive to intensity distortions, contrast agent and noise. Although residual complexity can solve this problem in certain situations, relative modification of the parameter can generate dramatically different results. By introducing a specifically designed exponential weighting function to the residual term in residual complexity, the proposed similarity measure performed well due to automatically weighting the residual image between the reference image and the warped floating image. We utilized local variance of the reference image to model the exponential weighting function. The proposed technique was applied to brain magnetic resonance images, dynamic contrast enhanced magnetic resonance images (DCE-MRI) of breasts and contrast enhanced 3D CT liver images. The experimental results clearly indicated that the proposed approach has achieved more accurate and robust performance than mutual information, residual complexity and Jensen-Tsallis.
    Computers in Biology and Medicine 10/2013; 43(10):1484-96. DOI:10.1016/j.compbiomed.2013.07.017 · 1.24 Impact Factor
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    ABSTRACT: To propose a new method for automatic segmentation of manually determined knee articular cartilage into 9 subregions for T2 measurement. The middle line and normal line were automatically obtained based on the outline of articular cartilage manually drawn by experienced radiologists. The region of articular cartilage was then equidistantly divided into 3 layers along the direct0ion of the normal line, and each layer was further equidistantly divided into 3 segments along the direction of the middle line. Finally the mean T2 value of each subregion was calculated. Bland-Altman analysis was used to evaluate the agreement between the proposed and manual subregion segmentation methods. The 95% limits of agreement of manual and automatic methods ranged from -3.04 to 3.20 ms, demonstrating a narrow 95% limits of agreement (less than half of the minimum average). The coefficient of variation between the manual and proposed subregion methods was 4.04%. The proposed subregion segmentation method shows a good agreement with the manual segmentation method and minimizes potential subjectivity of the manual method.
    Nan fang yi ke da xue xue bao = Journal of Southern Medical University 06/2013; 33(6):874-877.
  • Ning Wang · Wu-fan Chen · Qian-jin Feng ·
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    ABSTRACT: Vessel enhancing diffusion (VED) algorithm follows a multiscale approach to enhance vessels using a nonlinear anisotropic diffusion scheme. This method performs better than most of the existing techniques in visualizing vessels with varying radii and in enhancing vessel appearance. But typical medical images have high resolution and grayscale, selection of multiscale and computation of nonlinear anisotropic diffusion partial differential equation have a large computational burden, the algorithm has a low execution rate thus is are not suitable for its applications in practice. This paper proposed an angiogram images enhancement method based on GPU. By taking use of the independence of image pixel and concurrence of partial differential equation, the vessel enhancing diffusion algorithm was parallel implemented on compute unified device architecture (CUDA). Experimental results show that this method not only maintains the same good performance of vessel enhancement but also greatly reduces the computing time with the speed ratio of more than twenty seven times.
    01/2013: pages 868-871;
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    Hai-jun Niu · Qing Wang · Yue-xiang Wang · De-yu Li · Yu-bo Fan · Wu-fan Chen ·
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    ABSTRACT: Early diagnosis of osteoarthritis (OA) is essential for preventing further cartilage destruction and decreasing severe complications. The aims of this study are to explore the relationship between OA pathological grades and quantitative acoustic parameters and to provide more objective criteria for ultrasonic microscopic evaluation of the OA cartilage. Articular cartilage samples were prepared from rabbit knees and scanned using ultrasound biomicroscopy (UBM). Three quantitative parameters, including the roughness index of the cartilage surface (URI), the reflection coefficients from the cartilage surface (R) and from the cartilage-bone interface (Rbone) were extracted. The osteoarthritis grades of these cartilage samples were qualitatively assessed by histology according to the grading standards of International Osteoarthritis Institute (OARSI). The relationship between these quantitative parameters and the osteoarthritis grades was explored. The results showed that URI increased with the OA grade. URI of the normal cartilage samples was significantly lower than the one of the OA cartilage samples. There was no significant difference in URI between the grade 1 cartilage samples and the grade 2 cartilage samples. The reflection coefficient of the cartilage surface reduced significantly with the development of OA (p < 0.05), while the reflection coefficient of the cartilage-bone interface increased with the increase of grade. High frequency ultrasound measurements can reflect the changes in the surface roughness index and the ultrasound reflection coefficients of the cartilage samples with different OA grades. This study may provide useful information for the quantitative ultrasonic diagnosis of early OA.
    BMC Musculoskeletal Disorders 03/2012; 13:34. DOI:10.1186/1471-2474-13-34 · 1.72 Impact Factor
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    ABSTRACT: OBJECTIVE: Concerns have been raised over x-ray radiation dose associated with repeated computed tomography (CT) scans for tumor surveillance and radiotherapy planning. In this paper, we present a low-dose CT image reconstruction method for improving low-dose CT image quality. The method proposed exploited rich redundancy information from previous normal-dose scan image for optimizing the non-local weights construction in the original non-local means (NLM)-based low-dose image reconstruction. The objective 3D low-dose volume and the previous 3D normal-dose volume were first registered to reduce the anatomic structural dissimilarity between the two datasets, and the optimized non-local weights were constructed based on the registered normal-dose volume. To increase the efficiency of this method, GPU was utilized to accelerate the implementation. The experimental results showed that this method obviously improved the image quality, as compared with the original NLM method, by suppressing the noise-induced artifacts and preserving the edge information.
    Nan fang yi ke da xue xue bao = Journal of Southern Medical University 12/2011; 31(12):1974-80.
  • Jie Peng · Qi-fei Xu · Yan-qiu Feng · Qing-wen Lv · Wu-fan Chen ·
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    ABSTRACT: OBJECTIVE: To increase the resolution and signal-to-noise ratio (SNR) of magnetic resonance (MR) images, an adaptively regularized super-resolution reconstruction algorithm was proposed and applied to acquire high resolution MR images from 4 subpixel-shifted low resolution images on the same anatomical slice. The new regularization parameter, which allowed the cost function of the new algorithm to be locally convex within the definition region, was introduced by the piori information to enhance detail restoration of the image with a high frequency. The experiment results proved that the proposed algorithm was superior to other counterparts in achieving the reconstruction of low-resolution MR images.
    Nan fang yi ke da xue xue bao = Journal of Southern Medical University 10/2011; 31(10):1705-8.
  • Xin Huang · Wu-Fan Chen · Yan-Qiu Feng ·
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    ABSTRACT: Partial Fourier acquisition and parallel imaging are two effective fast imaging techniques. Both techniques permit decreased acquisition times by reducing the amount of phased encoding needed. The benefits of the combined technique compared with the individual techniques are large reduced imaging time. Unfortunately, during the partial Fourier reconstruction processing, restoration of missing uncollected k-space data rely on corrupt Hermitian conjugate symmetry. This leads to minor phase variations and noise introduced, which in turn corrupt in SENSE process. In this paper, a constrained reconstruction algorithm is presented to remove artifact in images. We apply robust Annealing M (AM) Estimator scheme to suppress the corrupt data points and make solutions insensitive to the influence caused by outliers. Experimental results show that proposed method can effectively eliminate aliasing artifacts to enhance quality of reconstruction and imaging speed.
    Chinese Journal of Computers 09/2011; 34(9):1732-1738. DOI:10.3724/SP.J.1016.2011.01732
  • Shuan-qiang Li · Qian-jin Feng · Wu-fan Chen · Ya-zhong Lin ·
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    ABSTRACT: For accurate segmentation of the magnetic resonance (MR) images of meningioma, we propose a novel interactive segmentation method based on graph cuts. The high dimensional image features was extracted, and for each pixel, the probabilities of its origin, either the tumor or the background regions, were estimated by exploiting the weighted K-nearest neighborhood classifier. Based on these probabilities, a new energy function was proposed. Finally, a graph cut optimal framework was used for the solution of the energy function. The proposed method was evaluated by application in the segmentation of MR images of meningioma, and the results showed that the method significantly improved the segmentation accuracy compared with the gray level information-based graph cut method.
    Nan fang yi ke da xue xue bao = Journal of Southern Medical University 07/2011; 31(7):1164-8.
  • Mei Yu · Zhen-tai Lu · Wu-fan Chen ·
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    ABSTRACT: OBJECTIVE: This paper presents a method for global feature extraction and the application of the boostmetric distance metric method for medical image retrieval. The global feature extraction method used the low frequency subband coefficient of the wavelet decomposition based on the non-tensor product coefficient for piecewise Gaussian fitting. The local features were extracted after semi-automatic segmentation of the lesion areas in the images in the database. The experimental verification of the method using 1688 CT images of the liver containing lesions of liver cancer, liver angioma, and liver cyst confirmed that this feature extraction method improved the detection rate of the lesions with good image retrieval performance.
    Nan fang yi ke da xue xue bao = Journal of Southern Medical University 02/2011; 31(2):221-5.
  • Nan Liu · Jing Huang · Jian-hua Ma · Li-jun Lu · Qian-jin Feng · Wu-fan Chen ·
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    ABSTRACT: Based on the fact that nonlocal means (NL-means) filtered image can likely produce an acceptable priori solution, we propose a sparse angular CT projection onto convex set (POCS) reconstruction using NL-means iterative modification. The new reconstruction scheme consists of two components, POCS and NL-means filter. In each phase of the sparse angular CT iterative reconstruction, we first used POCS algorithm to meet the identity and non-negativity of projection data, and then performed NL-means filter to the image obtained by POCS method for image quality improvement. Simulation experiments showed that the proposed POCS scheme can significantly improve the quality of sparse angular CT image by suppressing the noise and removing the streak-artifacts.
    Nan fang yi ke da xue xue bao = Journal of Southern Medical University 10/2010; 30(10):2224-8.
  • Jie Peng · Qing-wen Lü · Yan-qiu Feng · Yuan-yuan Gao · Wu-fan Chen ·
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    ABSTRACT: With the utilization of diffusion tensor information of image voxels, a novel MRF (Markov Random Field) segmentation algorithm was proposed for diffusion tensor MRI (DT-MRI) images benefitted from the introduction of Frobenius norm. The comparison of the segmentation effects between the proposed algorithm and K-means segmentation algorithm for DT-MRI image was made, which showed that the new algorithm could segment the DT-MRI images more accurately than the K-means algorithm. Moreover, with the same segmentation algorithm of MRF, better outcomes were achieved in DT-MRI than in conventional MRI (T2WI) image.
    Nan fang yi ke da xue xue bao = Journal of Southern Medical University 07/2010; 30(7):1562-4, 1572.
  • Jing Huang · Jian-hua Ma · Ling-jian Chen · Yi-ming Bi · Wu-fan Chen ·
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    ABSTRACT: The medical CT scanner is rapidly evolving from the fan-beam mode to the cone-beam geometry mode. In this paper, a new cone-beam pseudo Lambda tomography was proposed based on the Noo's fan beam super-short scan formula and FDK framework. The proposed pseudo-LT algorithm, which avoids the computation of any PI line and any differential operation, has a significant practical implementation, thus leading to the images with quality improvement and reduced artifacts. The results in the simulation studies confirm the observation that the new algorithm can improve the image resolution over the traditional algorithms with noise projection data.
    Nan fang yi ke da xue xue bao = Journal of Southern Medical University 10/2009; 29(10):2094-7.
  • Jie Peng · Qi-fei Xu · Qing-wen Lv · Zhi-yuan Wang · Yan-qiu Feng · Wu-fan Chen ·
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    ABSTRACT: OBJECTIVE: A new algorithm of adaptive super-resolution (SR) reconstruction based on the regularization parameter is proposed to reconstruct a high-resolution (HR) image from the low-resolution (LR) image sequence, which takes into full account the inaccurate estimates of motion error, point spread function (PSF) and the additive Gaussian noise in the LR image sequence. We established a novel nonlinear adaptive regularization function and analyzed experimentally its convexity to obtain the adaptive step size. This novel algorithm can effectively improve the spatial resolution of the image and the rate of convergence, which is verified by the experiment on optical images.
    Nan fang yi ke da xue xue bao = Journal of Southern Medical University 05/2009; 29(4):656-8.
  • Lei Cao · Li-jun Lu · Rui-meng Yang · Wu-fan Chen ·
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    ABSTRACT: To improve the accuracy and efficiency of pulmonary nodule segmentation of thoracic CT image for computer-aided diagnostic (CAD) system, especially for those nodules adhering to the pleural or blood vessels. We proposed the automatic process of pulmonary nodule segmentation, and using region growing method based on the contrast and gradient, the pulmonary nodule images were acquired. A self-adapted morphologic segmentation algorithm was presented for the unsuccessful nodule segmentation using region growing. Experiments on clinical 2D pulmonary images showed that the solitary pulmonary nodules and those adhering to the pleural or blood vessels could all be segmented. This pulmonary nodule segmentation algorithm is feasible for automated segmentation of the thoracic CT images.
    Nan fang yi ke da xue xue bao = Journal of Southern Medical University 01/2009; 28(12):2109-12.
  • Zhen-tai Lu · Wu-fan Chen ·
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    ABSTRACT: This paper presents a new 3-D image registration method based on the principal component analysis (PCA). Compared with intensity-based registration methods using the whole volume intensity information, our approach utilizes PCA to estimate the centroid and principal axis, and completes the registration by aligning the centroid and principal axis. We evaluated the effectiveness of this approach by applying it to simulated and actual brain image data (MR, CT, PET, and SPECT). The experimental results indicate that the algorithm is effective, especially for registration of 3-D medical images.
    Nan fang yi ke da xue xue bao = Journal of Southern Medical University 10/2008; 28(9):1591-3.
  • Jian-Hua Ma · Ling-Jian Chen · Gang Yan · Wu-Fan Chen ·
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    ABSTRACT: We present an alternative approach for precise reconstruction of the images from helical cone-beam projections combining Hilbert filter and Ramp filter. Based on the Katsevich algorithm framework, the proposed algorithm combined the FDK-type algorithms and Katsevich algorithm for their respective advantages, to completely avoid the direct derivatives with respect to the coordinates on the detector plane. The experimental results validated the accuracy of the new algorithm, and this approach significantly improved the resolution of the reconstructed images with much reduced artifacts. The proposed reconstruction formula based on hybrid Hilbert-Ramp filter is an important development of Katsevich reconstruction formula, and the different forms of the Ramp filters can be designed to realize frequency modulation according to the actual clinical application.
    Nan fang yi ke da xue xue bao = Journal of Southern Medical University 07/2008; 28(6):911-4.