Bio-Medical Materials and Engineering - Volume 24, issue 1

Authors: He, Zhengyao

Article Type: Research Article

Abstract: A method is proposed to calculate the weight vector of a transducer array for ultrasound imaging to obtain a low-sidelobe transmitting beam pattern based on the near-field response vector. An optimization problem is established, and the second-order cone (SOC) algorithm is used to solve the problem to obtain the weight vector. The optimized acoustic emitted field of the transducer array is then calculated using the Field II program by applying the obtained weight vector to the array. The simulation results with a 64-element 26 MHz linear phased array show that the proposed method can be used to control the sidelobe …of the near-field transmitting beam pattern of the transducer array and achieve a low-sidelobe level. The near-field sound pressure distribution of the transducer array using the proposed method focuses much better than that using the standard delay and sum (DAS) beamforming method. The sound energy is more concentrated using the proposed method. Show more

Keywords: transducer array, acoustic emitted field, optimization, ultrasound imaging

DOI: 10.3233/BME-130921

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 1, pp. 1201-1208, 2014

Authors: Gao, Shuang | Peng, Yuhua | Guo, Huizhi | Liu, Weifeng | Gao, Tianxin | Xu, Yuanqing | Tang, Xiaoying

Article Type: Research Article

Abstract: Ultrasound as a noninvasive imaging technique is widely used to diagnose liver diseases. Texture analysis and classification of ultrasound liver images have become an important research topic across the world. In this study, GLGCM (Gray Level Gradient Co-Occurrence Matrix) was implemented for texture analysis of ultrasound liver images first, followed by the use of GLCM (Gray Level Co-occurrence Matrix) at the second stage. Twenty two features were obtained using the two methods, andseven most powerful features were selected for classification using BP (Back Propagation) neural network. Fibrosis was divided into five stages (S0–S4) in this study. The classification accuracies of …S0–S4 were 100%, 90%, 70%, 90% and 100%, respectively. Show more

Keywords: liver fibrosis, ultrasonic image, texture features analysis, texture features extraction, artificial neural network

DOI: 10.3233/BME-130922

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 1, pp. 1209-1216, 2014

Authors: Wang, Rui-hao | Zhang, Shu-xu | Zhou, Ling-hong | Zhang, Guo-qian | Yu, Hui | Lin, Xiao-dan | Lin, Shengqu

Article Type: Research Article

Abstract: The aims of this study were to evaluate the volume and dosimetric variations during IMRT for locally advanced NPC and to identify the benefits of a two-phase adaptive IMRT method. Twenty patients with locally advanced NPC having received IMRT treatment were included. Each patient had both an initial planning CT (CT-1) and a repeated CT scan (CT-2) after treatment at a dose of 40 Gy. Three IMRT planning scenarios were compared: (1) the initial plan on the CT-1 (plan-1); (2) the hybrid plan recalculated the initial plan on the CT-2 (plan-2); (3) the replan generated on the CT-2 being used …to complete the course of IMRT (plan-3). The mean gross target volume and mean volumes of the positive neck lymph nodes, high-risk clinical target volume, and the left and right parotid glands significantly decreased by 30.2%, 45.1%, 21.1%, 14.7% and 18.2%, respectively on the CT-2. Comparing plan-2 with plan-1, the dose coverage of the targets remained unchanged, whereas the dose delivered to the parotid glands and spinal cord increased significantly. These patients with locally advanced NPC might benefit from replanning because of the sparing of the parotid glands and spinal cord. Show more

Keywords: Nasopharyngeal carcinoma, intensity-modulated radiotherapy, anatomic changes, adaptive replanning

DOI: 10.3233/BME-130923

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 1, pp. 1217-1225, 2014

Authors: Zhang, Xubing | Zhang, Penglin | Hirai, Shinichi

Article Type: Research Article

Abstract: Due to the nonlinear and nonuniform local deformation of nonrigid tissues, it is difficult to match a number of feature points distributing somewhat uniform in the tissues from MR images for deformation measurement. This paper proposes TSSC (TPS-SURF-SAC-Clustering) based method of feature point matching and elimination of mismatching. First, Fast-Hessian and Harris operator are utilized to extract the feature points in the initial MR image, and the matching region is identified by TPS transformation model for every query point in the deformed image. Then the SURF descriptors and the proposed Spatial Association Correspondence (SAC) method are combined to match the …feature points. Finally, by clustering the coordinate differences between the matching points obtained by TPS-SURF-SAC and the matching points calculated by TPS model, most incorrectly matched points are eliminated. After every iterative processing of matching and mismatching elimination, the updated TPS model becomes more accurate and more correctly so that the matched points can be identified than those of last iteration. The experimental results show that the proposed SAC was efficient and that TSSC based method outperformed the single SURF or SIFT method. Show more

Keywords: Feature point, extraction, matching, deformation

DOI: 10.3233/BME-130924

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 1, pp. 1227-1237, 2014

Authors: Wang, Shanshan | Xia, Yong | Dong, Pei | Luo, Jianhua | Huang, Qiu | Feng, Dagan | Li, Yuanxiang

Article Type: Research Article

Abstract: Due to the imperfections of the radio frequency (RF) coil or object-dependent electrodynamic interactions, magnetic resonance (MR) images often suffer from a smooth and biologically meaningless bias field, which causes severe troubles for subsequent processing and quantitative analysis. To effectively restore the original signal, this paper simultaneously exploits the spatial and gradient features of the corrupted MR images for bias correction via the joint entropy regularization. With both isotropic and anisotropic total variation (TV) considered, two nonparametric bias correction algorithms have been proposed, namely IsoTVBiasC and AniTVBiasC. These two methods have been applied to simulated images under various noise levels …and bias field corruption and also tested on real MR data. The test results show that the proposed two methods can effectively remove the bias field and also present comparable performance compared to the state-of-the-art methods. Show more

Keywords: Bias correction, magnetic resonance (MR) images, joint entropy, total variation (TV)

DOI: 10.3233/BME-130925

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 1, pp. 1239-1245, 2014

Authors: Wen, Junling | Yan, Zhuangzhi | Jiang, Jiehui

Article Type: Research Article

Abstract: The lattice Boltzmann (LB) method is a mesoscopic method based on kinetic theory and statistical mechanics. The main advantage of the LB method is parallel computation, which increases the speed of calculation. In the past decade, LB methods have gradually been introduced for image processing, e.g., image segmentation. However, a major shortcoming of existing LB methods is that they can only be applied to the processing of medical images with intensity homogeneity. In practice, however, many medical images possess intensity inhomogeneity. In this study, we developed a novel LB method to integrate edge and region information for medical image segmentation. …In contrast to other segmentation methods, we added edge information as a relaxing factor and used region information as a source term. The proposed method facilitates the segmentation of medical images with intensity inhomogeneity and it still allows parallel computation. Preliminary tests of the proposed method are presented in this paper. Show more

Keywords: active contour method, lattice Boltzmann (LB) method, level set method, partial differential equation

DOI: 10.3233/BME-130926

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 1, pp. 1247-1252, 2014

Authors: Wen, Ying | He, Lianghua

Article Type: Research Article

Abstract: The aim of this study is to design a statistical segmentation technique to allow extraction of grey matter, white matter and cerebral spinal fluid volumes from diffusion tensor imaging. Four channel maps of the DTI are used as the input features, which provide more information for brain tissue segmentation compared with single channel map. An Improved Bayesian decision in the subspace spanned by the eigenvectors which are associated with the smaller eigenvalues in each class is adopted as the brain tissue segmentation criterion. Our method performed well, giving an average segmentation accuracy of about 0.88, 0.85 and 0.76 for white …matter, gray matter and cerebrospinal fluid respectively in terms of volume overlap. Show more

Keywords: Diffusion tensor imaging, image segmentation, bayesian decision

DOI: 10.3233/BME-130927

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 1, pp. 1253-1259, 2014

Authors: Wang, Weiming | Qin, Jing | Zhu, Lei | Ni, Dong | Chui, Yim-Pan | Heng, Pheng-Ann

Article Type: Research Article

Abstract: Due to the characteristic artifacts of ultrasound images, e.g., speckle noise, shadows and intensity inhomogeneity, traditional intensity-based methods usually have limited success on the segmentation of fetal abdominal contour. This paper presents a novel approach to detect and measure the abdominal contour from fetal ultrasound images in two steps. First, a local phase-based measure called multiscale feature asymmetry (MSFA) is de ned from the monogenic signal to detect the boundaries of fetal abdomen. The MSFA measure is intensity invariant and provides an absolute measurement for the signi cance of features in the image. Second, in order to detect the ellipse …that ts to the abdominal contour, the iterative randomized Hough transform is employed to exclude the interferences of the inner boundaries, after which the detected ellipse gradually converges to the outer boundaries of the abdomen. Experimental results in clinical ultrasound images demonstrate the high agreement between our approach and manual approach on the measurement of abdominal circumference (mean sign difference is 0.42% and correlation coef cient is 0.9973), which indicates that the proposed approach can be used as a reliable and accurate tool for obstetrical care and diagnosis. Show more

Keywords: Ultrasound images, fetal abdominal contour, multiscale feature asymmetry, iterative randomized Hough transform

DOI: 10.3233/BME-130928

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 1, pp. 1261-1267, 2014

Authors: Chen, Yongjun | Luo, Yuanfang | Jia, Zhixin | Jia, Demin | Chen, Juan

Article Type: Research Article

Abstract: In this work, a novel silicone rubber/nano-copper nanocomposite for use in intrauterine devices (IUDs) was developed. Moreover, the release rate of Cu2+ ions and the water absorption of the prepared nanocomposite were investigated in detail. The results indicate that the release rate of Cu2+ ions and water absorption capability of the silicone rubber/nanocopper nanocomposite increase as the nano-copper content increases. SEM analysis suggested there is a uniform dispersion of nano-copper in the silicone matrix. Further, systematic analysis indicated that the release rate of Cu2+ ions in the prepared nanocomposite-based IUD can be stabilized for months, which is …not possible in the case of traditional IUDs. Show more

Keywords: silicone rubber, nano-copper, nanocomposites, intrauterine devices

DOI: 10.3233/BME-130929

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 1, pp. 1269-1274, 2014

Authors: Sun, Yuchun | Yuan, Fusong | Li, Hong | Zhao, Yijiao | Lv, Peijun | Wang, Yong

Article Type: Research Article

Abstract: This study was to design a method to quantitatively evaluate three-dimensional (3D) reconstruction accuracy of spatial relationship of dental models based on a 7-axis contact 3D measuring system, and to evaluate the accuracy of a common regional registration method for edentulous jaw relation reconstruction. 3D surface data of edentulous dental casts with 10 positioning cylinders and wax occlusion rims of five patients were obtained using a dental scanner. The jaw relation was reconstructed using the common regional registration in the Geomagic software. Measurements were obtained for line length, vertical distance and horizontal distance between centric points from two sources with …upper jaw model base plane as a reference plane. The statistical description of measurement data was done. $\bar{x}\pm s$ of line length, vertical distance and horizontal distance between the center points of each data set were 0.107±0.354, 0.076±0.576 and 0.108±0.530 mm, respectively. Data was analyzed using the paired samples t-test and one-way analysis of variance. Paired t-test results of each patient and one-way analysis of variance for the five patients showed no significant differences (P>0.05). Using the Faro Edge system and standardized positioning cylinders, quantitative evaluation of the 3D reconstruction accuracy of edentulous jaw relation was workable. And results of common regional registration method met clinical requirements. Show more

Keywords: Edentulous jaw, jaw relation, three-dimensional scanning, three-dimensional reconstruction

DOI: 10.3233/BME-130930

Citation: Bio-Medical Materials and Engineering, vol. 24, no. 1, pp. 1275-1287, 2014