National Regional Key Technology Engineering Laboratory for Medical Ultrasound

Shenzhen, China

National Regional Key Technology Engineering Laboratory for Medical Ultrasound

Shenzhen, China

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Yang S.,National Regional Key Technology Engineering Laboratory for Medical Ultrasound | Yang S.,Shenzhen University | Du P.,National Regional Key Technology Engineering Laboratory for Medical Ultrasound | Du P.,Shenzhen University | And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

Terahertz (THz) spectroscopy is sensitive to probe several aspects of biological systems. In THz frequency, electrically controllable Drude-like intraband absorption makes graphene a promising platform for building graphene-based optoelectronic devices such as THz biosensor. In this work, BSA protein thin films were spin-coated and incubated on single-layer graphene. IR lasers with different power were used as the pump light to stimulate the sandwich-like sample respectively. The graphene monolayer complex conductivity was calculated using the transmission method. The novel optical properties of single-layer graphene and BSA protein on graphene in the THz range will be discussed in this paper. © 2016 SPIE.


Zhang L.,Shenzhen University | Zhang L.,University of Iowa | Zhang L.,National Regional Key Technology Engineering Laboratory for Medical Ultrasound | Zhang L.,Guangdong Key Laboratory of Biomedical Information Detection | And 12 more authors.
Computerized Medical Imaging and Graphics | Year: 2014

Automation-assisted reading (AAR) techniques have the potential to reduce errors and increase productivity in cervical cancer screening. The sensitivity of AAR relies heavily on automated segmentation of abnormal cervical cells, which is handled poorly by current segmentation algorithms. In this paper, a global and local scheme based on graph cut approach is proposed to segment cervical cells in images with a mix of healthy and abnormal cells. For cytoplasm segmentation, the multi-way graph cut is performed globally on the a* channel enhanced image, which can be effective when the image histogram presents a non-bimodal distribution. For segmentation of nuclei, especially when they are abnormal, we propose to use graph cut adaptively and locally, which allows the combination of intensity, texture, boundary and region information. Two concave points-based approaches are integrated to split the touching-nuclei. As part of an ongoing clinical trial, preliminary validation results obtained from 21 cervical cell images with non-ideal imaging condition and pathology show that our segmentation method achieved 93% accuracy for cytoplasm, and 88.4% F-measure for abnormal nuclei, outperforming state of the art methods in terms of accuracy. Our method has the potential to improve the sensitivity of AAR in screening for cervical cancer. © 2014 Elsevier Ltd.


Zhang L.,Shenzhen University | Zhang L.,National Regional Key Technology Engineering Laboratory for Medical Ultrasound | Zhang L.,Guangdong Key Laboratory of Biomedical Information Detection and Ultrasound Imaging | Kong H.,Massachusetts Institute of Technology | And 9 more authors.
Bio-Medical Materials and Engineering | Year: 2014

This paper proposes a method to segment the cytoplasm in cervical cell images using graph cut-based algorithm. First, the A* channel in CIE LAB color space is extracted for contrast enhancement. Then, in order to effectively extract cytoplasm boundaries when image histograms present non-bimodal distribution, Otsu multiple thresholding is performed on the contrast enhanced image to generate initial segments, based on which the segments are refined by the multi-way graph cut method. We use 21 cervical cell images with non-ideal imaging condition to evaluate cytoplasm segmentation performance. The proposed method achieved a 93% accuracy which outperformed state-of-the-art works. © 2014 - IOS Press and the authors. All rights reserved.


Zhang L.,Shenzhen University | Zhang L.,National Regional Key Technology Engineering Laboratory for Medical Ultrasound | Zhang L.,Guangdong Key Laboratory of Biomedical Information Detection and Ultrasound Imaging | Kong H.,Massachusetts Institute of Technology | And 11 more authors.
Cytometry Part A | Year: 2014

Current automation-assisted technologies for screening cervical cancer mainly rely on automated liquid-based cytology slides with proprietary stain. This is not a cost-efficient approach to be utilized in developing countries. In this article, we propose the first automation-assisted system to screen cervical cancer in manual liquid-based cytology (MLBC) slides with hematoxylin and eosin (H&E) stain, which is inexpensive and more applicable in developing countries. This system consists of three main modules: image acquisition, cell segmentation, and cell classification. First, an autofocusing scheme is proposed to find the global maximum of the focus curve by iteratively comparing image qualities of specific locations. On the autofocused images, the multiway graph cut (GC) is performed globally on the a* channel enhanced image to obtain cytoplasm segmentation. The nuclei, especially abnormal nuclei, are robustly segmented by using GC adaptively and locally. Two concave-based approaches are integrated to split the touching nuclei. To classify the segmented cells, features are selected and preprocessed to improve the sensitivity, and contextual and cytoplasm information are introduced to improve the specificity. Experiments on 26 consecutive image stacks demonstrated that the dynamic autofocusing accuracy was 2.06 μm. On 21 cervical cell images with nonideal imaging condition and pathology, our segmentation method achieved a 93% accuracy for cytoplasm, and a 87.3% F-measure for nuclei, both outperformed state of the art works in terms of accuracy. Additional clinical trials showed that both the sensitivity (88.1%) and the specificity (100%) of our system are satisfyingly high. These results proved the feasibility of automation-assisted cervical cancer screening in MLBC slides with H&E stain, which is highly desirable in community health centers and small hospitals. © 2013 International Society for Advancement of Cytometry.


Li J.,Shenzhen University | Li J.,Chinese University of Hong Kong | Zhou Y.,Shenzhen University | Zhou Y.,National Regional Key Technology Engineering Laboratory for Medical Ultrasound | And 3 more authors.
Ultrasonics | Year: 2015

Abstract Muscle force output is an essential index in rehabilitation assessment or physical exams, and could provide considerable insights for various applications such as load monitoring and muscle assessment in sports science or rehabilitation therapy. Besides direct measurement of force output using a dynamometer, electromyography has earlier been used in several studies to quantify muscle force as an indirect means. However, its spatial resolution is easily compromised as a summation of the action potentials from neighboring motor units of electrode site. To explore an alternative method to indirectly estimate the muscle force output, and with better muscle specificity, we started with an investigation on the relationship between architecture dynamics and force output of triceps surae. The muscular architecture dynamics is captured in ultrasonography sequences and estimated using a previously reported motion estimation method. Then an indicator named as the dorsoventrally averaged motion profile (DAMP) is employed. The performance of force output is represented by an instantaneous version of the rate of force development (RFD), namely I-RFD. From experimental results on ten normal subjects, there were significant correlations between the I-RFD and DAMP for triceps surae, both normalized between 0 and 1, with the sum of squares error at 0.0516±0.0224, R-square at 0.7929±0.0931 and root mean squared error at 0.0159±0.0033. The statistical significance results were less than 0.01. The present study suggested that muscle architecture dynamics extracted from ultrasonography during contraction is well correlated to the I-RFD and it can be a promising option for indirect estimation of muscle force output. © 2015 Elsevier B.V.


Sun Y.,National Regional Key Technology Engineering Laboratory for Medical Ultrasound | Sun Y.,Shenzhen University | Zhong J.,National Regional Key Technology Engineering Laboratory for Medical Ultrasound | Zhong J.,Shenzhen University | And 2 more authors.
IRMMW-THz 2015 - 40th International Conference on Infrared, Millimeter, and Terahertz Waves | Year: 2015

In this paper, we concerned with the spectrum analysis of binding interaction of recombinant heamaglutining (HA) antigen against its own antibody in terahertz frequency using principle component analysis (PCA). 21 liquid samples with different component were divided into positive and negative control groups and measured using THz-TDS in transmission geometry. The spectral pretreatment methods were adopted to make our results more explicit in this study. As a result, HA complexes are distinguished by different scores which indicate the PCA method can be used to identify the antigen-antibody binding interaction in THz frequency. © 2015 IEEE.


Zhuo Y.,National Regional Key Technology Engineering Laboratory for Medical Ultrasound | Ni D.,National Regional Key Technology Engineering Laboratory for Medical Ultrasound | Chen S.,National Regional Key Technology Engineering Laboratory for Medical Ultrasound | Lei B.,National Regional Key Technology Engineering Laboratory for Medical Ultrasound | And 2 more authors.
2015 10th International Conference on Information, Communications and Signal Processing, ICICS 2015 | Year: 2015

In this paper, a new multipurpose watermarking scheme is proposed to provide protection and authentication of medical data. To achieve both purposes, integer discrete wavelet transform (IDWT) decomposition is first performed, and then robust watermark (e.g. logo data) is embedded in the low frequency IDWT sub-band for copiright protection, while fragile watermark (e.g. The diagnosis information) is inserted in the high frequency IDWT sub-band for tampering detection. A tradeoff between conflicting watermark requirements such as robustness, capacity and imperceptibility is achieved by particle swarm optimization (PSO) training technique. Experimental results validate the effectiveness and efficiency of the proposed algorithm. The achieved fragileness and robustness confirmed that the proposed scheme has capability of rightful ownership protection and authentication simultaneously. © 2015 IEEE.


Dan G.,Shenzhen University | Dan G.,National Regional Key Technology Engineering Laboratory for Medical Ultrasound | Dan G.,Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging | Li Z.,Shenzhen University | And 3 more authors.
IFMBE Proceedings | Year: 2015

In recent decades, a new attempt at estimating respiratory rate (RR) from Photoplethysmogram (PPG) becomes an active area. It can be implemented by different algorithms among of which wavelet based methods are commonly used with good performances achieved. However, the study on the reason why different mother wavelets have different performances on RR estimation as well as how a suitable wavelet can be easily selected is insufficient. In this paper, a mother wavelet selection algorithm is proposed for RR estimation from PPG signal. Six popular mother wavelets, namely db10, db12, sym8, bior6.8, rbio6.8 and coif5, are compared in terms of the sum of decomposition coefficient magnitudes and the one with maximum value is chosen for RR information extraction and reconstruction. In the experiments, the proposed algorithm is compared with the related six mother wavelets working separately. Two evaluation tools, root mean squared normalized error (RMSNE) and Bland & Altman plot, are adopted. The evaluation results demonstrate the better performance of the proposed algorithm. In addition, the above finding reveals that the mother wavelet with a larger sum of coefficient magnitudes has a better performance on RR estimation from PPG signal which can be used as wavelet selection criteria in this area. © Springer International Publishing Switzerland 2015.


Li B.,Shenzhen University | Li B.,National Regional Key Technology Engineering Laboratory for Medical Ultrasound | Li B.,Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging | Xu G.,CAS Shenzhen Institutes of Advanced Technology | And 4 more authors.
Medical Physics | Year: 2015

Purpose:Wireless capsule endoscopy (WCE) opens a newdoor for the digestive tract examination and diagnosis. However, the examination of its video data is tedious. This study aims to assist a physician to interpret a WCE video by segmenting it into different anatomic parts in the digestive tract. Methods: A two level WCE video segmentation scheme is proposed to locate the boundary between the stomach, small intestine, and large intestine. In the rough level, the authors utilize color feature to draw a dissimilarity curve for a WCE video and obtain an approximate boundary. Meanwhile, training data for the fine level segmentation can be collected automatically between the two approximate boundaries of organs to overcome the difficulty of training data collection in traditional approaches. In the fine level, color histogram in the HSI color space is used to segment the stomach and small intestine. Then, color uniform local binary pattern (CULBP) algorithm is applied for discrimination of the small intestine and large intestine, which includes two patterns, namely, color norm and color angle pattern. The CULBP feature is robust to variation of illumination and discriminative for classification. In order to increase the performance of support vector machine, the authors integrate it with the Adaboost approach. Finally, the authors refine the classification results to segment a WCE video into different parts, that is, the stomach, small intestine, and large intestine. Results: The average precision and recall are 91.2% and 90.6% for the stomach/small intestine classification, 89.2% and 88.7% for the small/large intestine discrimination. Paired t-test also demonstrates a significant better performance of the proposed scheme compared to some traditional methods. The average segmentation error is 8 frames for the stomach/small intestine discrimination, and 14 frames for the small/large intestine segmentation. Conclusions: The results have demonstrated that the new video segmentation method can accurately locate the boundary between different organ regions in a WCE video. Such a segmentation result may enhance the efficiency of WCE examination. © 2015 American Association of Physicists in Medicine.


Chen X.,Shenzhen University | Chen X.,National Regional Key Technology Engineering Laboratory for Medical Ultrasound | Chen X.,Guangdong Key Laboratory for Biomedical Measurements and Ultrasound Imaging | Shen Y.,Shenzhen University | And 15 more authors.
Ultrasound in Medicine and Biology | Year: 2013

Ultrasound elastography, based on shear wave propagation, enables the quantitative and non-invasive assessment of liver mechanical properties such as stiffness and has been found to be feasible for and useful in the diagnosis of hepatic fibrosis. Most ultrasound elastographic methods use a purely elastic model to describe liver mechanical properties. However, to describe tissue that is dispersive and to obtain an accurate measure of tissue elasticity, the viscoelasticity of the tissue should be examined. The objective of this study was to investigate the shear viscoelastic characteristics, as measured by ultrasound elastography, of liver fibrosis in a rat model and to evaluate the diagnostic accuracy of viscoelasticity for staging liver fibrosis. Liver fibrosis was induced in 37 rats using carbon tetrachloride (CCl4); 6 rats served as controls. Liver viscoelasticity was measured invitro using shear waves induced by acoustic radiation force. The measured mean values of liver elasticity and viscosity ranged from 0.84 to 3.45kPa and from 1.12 to 2.06Pa·s for fibrosis stages F0-F4, respectively. Spearman correlation coefficients indicated that stage of fibrosis was well correlated with elasticity (0.88) and moderately correlated with viscosity (0.66). The areas under receiver operating characteristic curves were 0.97 (≥F2), 0.91 (≥F3) and 1.00(F4) for elasticity and 0.91 (≥F2), 0.79 (≥F3) and 0.74 (F4) for viscosity, respectively. The results confirmed that shear wave velocity was dispersive in frequency, suggesting a viscoelastic model to describe liver fibrosis. The study finds that although viscosity is not as good as elasticity for staging fibrosis, it is important to consider viscosity to make an accurate estimation of elasticity; it may also provide other mechanical insights into liver tissues. © 2013 World Federation for Ultrasound in Medicine & Biology.

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