Bio-Medical Materials and Engineering - Volume 26, issue s1

Authors: Fan, Xiaoli | Zhou, Qianxiang | Liu, Zhongqi | Xie, Fang

Article Type: Research Article

Abstract: Based on the electrical properties of biological tissues, bioimpedance measurement technology can be employed to collect physiologic and pathologic information by measuring changes in human bioimpedance. When an alternating current (AC) is applied as a detection signal to a tissue, the current field distribution, which is affected by skin effect, is related to both the bioimpedance of the tissue and the AC frequency. These relations would possibly reduce the accuracy and reliability of the measurement. In this study, an electromagnetic theory-based method, in which cylindrical conductor were divided into layers, was used to obtain current field distribution models of human …limbs. Model simulations were conducted in MATLAB. The skin effect phenomenon and its characteristics in human tissues at different frequencies were observed, thus providing essential data on skin effect, which are useful in the development of bioimpedance measurement technology. Show more

Keywords: Skin effect, bioimpedance measurement technology, current density, conductivity

DOI: 10.3233/BME-151332

Citation: Bio-Medical Materials and Engineering, vol. 26, no. s1, pp. S429-S437, 2015

Authors: Zhang, Liang | Liu, Peiguo | Dong, Xiuzhen | Zhou, Dongming | Shi, Xuetao

Article Type: Research Article

Abstract: Thus far, the measurement of dielectric properties of biological tissues has been achieved on the assumption that the biological tissues are homogeneous. In fact, most tissues should be heterogeneous because there are many small structures included in these tissues, such as blood vessel, nerve fiber and so on. When the dielectric properties of these tissues are measured by conventional sensor, the results are not the dielectric properties of tissues but the effective dielectric properties of the mixture. In this paper, the influence of the inclusion in tissues on the measurement of dielectric properties of heterogeneous biological tissues is studied and …the analysis of the effective dielectric properties of heterogeneous tissues based on the mixing rule is proposed. When the coaxial probe is used to measure the dielectric properties of tissue, the results are relative to the dielectric properties of inclusion, dielectric properties of background tissue and the effective volume fraction of inclusion. Therefore, the dielectric properties of inclusion could be calculated according to mixing rule, after the effective dielectric properties are measured and the effective volume fraction of inclusion is estimated. Show more

Keywords: Dielectric properties, heterogeneous biological tissues, mixing rule, effective volume fraction

DOI: 10.3233/BME-151333

Citation: Bio-Medical Materials and Engineering, vol. 26, no. s1, pp. S439-S445, 2015

Authors: Zhu, Jianming | Chen, Zhencheng

Article Type: Research Article

Abstract: A non-invasive blood glucose measurement sensor and the data process algorithm based on the metabolic energy conservation (MEC) method are presented in this paper. The physiological parameters of human fingertip can be measured by various sensing modalities, and blood glucose value can be evaluated with the physiological parameters by the multiple linear regression analysis. Five methods such as enter, remove, forward, backward and stepwise in multiple linear regression were compared, and the backward method had the best performance. The best correlation coefficient was 0.876 with the standard error of the estimate 0.534, and the significance was 0.012 (sig. <0.05), which …indicated the regression equation was valid. The Clarke error grid analysis was performed to compare the MEC method with the hexokinase method, using 200 data points. The correlation coefficient R was 0.867 and all of the points were located in Zone A and Zone B, which shows the MEC method provides a feasible and valid way for non-invasive blood glucose measurement. Show more

Keywords: Non-invasive blood glucose measurement, metabolic energy conservation, multiple linear regression, Clarke error gird, sensor

DOI: 10.3233/BME-151334

Citation: Bio-Medical Materials and Engineering, vol. 26, no. s1, pp. S447-S453, 2015

Authors: Pan, Wenlei | Shen, Yi | Liu, Ting | Wang, Yan

Article Type: Research Article

Abstract: Mean scatterer spacing (MSS) estimated from ultrasonic backscattering is of valuable information for tissue characterization. However, low ultrasound frequency, sound attenuation, and diffuse scattering significantly disturb the current MSS measurement methods. The aim of this study is to improve MSS measurement with Coded Excitation (CE) enhanced cepstrum estimation. The study proposes a Golay code-based cepstrum estimation and uses an equivalent Faran cylinder model of cancellous bone. By solving the elastic wave equation, ultrasonic backscattering signals were obtained through simulations. The adopted ultrasonic excitation is 0.9 MHz and is coded with 4-bit complementary sequences, which is modulated by employing a sinusoidal …signal. Also, white Gaussian noise of 60 dB, 55 dB, and 45 dB was added to the backscattering data to study the robustness of the proposed method. Simulation results show that the Golay-based method successfully improved ultrasound energy transmission into the tissue and effectively suppressed interference peaks while identifying the right peaks with permitted errors. In addition, the robustness against noise was enhanced. Show more

Keywords: Golay codes, mean scatterer spacing, cepstrum estimation, ultrasonic backscattering

DOI: 10.3233/BME-151335

Citation: Bio-Medical Materials and Engineering, vol. 26, no. s1, pp. S455-S465, 2015

Authors: Sun, Zheng | Dong, Yi | Li, Mengchan

Article Type: Research Article

Abstract: Intracoronary ultrasound (ICUS) is a widely used interventional imaging modality in clinical diagnosis and treatment of cardiac vessel diseases. Due to cyclic cardiac motion and pulsatile blood flow within the lumen, there exist changes of coronary arterial dimensions and relative motion between the imaging catheter and the lumen during continuous pullback of the catheter. The action subsequently causes cyclic changes to the image intensity of the acquired image sequence. Information on cardiac phases is implied in a non-gated ICUS image sequence. A 1-D phase signal reflecting cardiac cycles was extracted according to cyclical changes in local gray-levels in ICUS images. …The local extrema of the signal were then detected to retrieve cardiac phases and to retrospectively gate the image sequence. Results of clinically acquired in vivo image data showed that the average inter-frame dissimilarity of lower than 0.1 was achievable with our technique. In terms of computational efficiency and complexity, the proposed method was shown to be competitive when compared with the current methods. The average frame processing time was lower than 30 ms. We effectively reduced the effect of image noises, useless textures, and non-vessel region on the phase signal detection by discarding signal components caused by non-cardiac factors. Show more

Keywords: Coronary arterial vessel, intracoronary ultrasound (ICUS), motion artifact, cardiac phase, retrospective gating

DOI: 10.3233/BME-151336

Citation: Bio-Medical Materials and Engineering, vol. 26, no. s1, pp. S467-S475, 2015

Authors: Bernad, Sandor I. | Bosioc, Alin I. | Bernad, Elena S. | Craina, Marius L.

Article Type: Research Article

Abstract: Optimal graft design has been an objective of many researchers to find correlations between hemodynamics and graft failure. Compared to planar grafts, the helical graft configurations improve hemodynamic performance including the promotion of flow mixing and reduction of flow stagnation regions. In order to evaluate the advantages and disadvantages of the suggested helical type bypass graft model in comparison to a conventional bypass graft configuration, three experimental models were designed and evaluated. The character of complex vortex structures created in the area between the heel and the occluded section depends on the flow parameters (in the case of the straight …graft). We have identified two vortices in the symmetrical plane (proximal and distal to the anastomosis). In the new design of the two-turn helical graft, the stagnation point is eliminated from the anastomoses at different time intervals compared to the conventional straight bypass model The present study indicated that the magnitude of the pressure drop along a helical graft was considerably increased compared to a traditional graft which, while still physiologically advantageous, can be surpassed by an optimal geometry model. Show more

Keywords: Bypass graft, helical graft, hemodynamics, pressure drop, anastomosis

DOI: 10.3233/BME-151337

Citation: Bio-Medical Materials and Engineering, vol. 26, no. s1, pp. S477-S486, 2015

Authors: Deng, Xin | Feng, Xuhui | Li, Sen | Gao, Ya | Yu, Bingzhi | Li, Gensong

Article Type: Research Article

Abstract: Previous literatures have indicated that hypothalamic paraventricular nucleus (PVN) neurons are important for regulating the level of sympathetic and vagal nervous activity. Sympathovagal balance is closely related to heart rate variability (HRV). However, it still requires further elucidation regarding the effect of PVN on HRV by regulating sympathovagal balance. To detect the influence of the PVN on HRV, we evaluated the changes in time domain (including standard deviation of the R-R intervals (SDNN), and the root mean square of successive differences (RMSSD)) and frequency domain (including low frequency (LFnu), high frequency (HFnu) and the ratio of LF/HF) in HRV upon …appropriate electronic stimulation, and lesions on the PVN of the rat in vivo. Cardiac vagal modulation was evaluated by HFnu; sympathetic modulation was evaluated by LFnu. Sympathovagal balance was evaluated by LF/HF and SDNN. Upon electronic stimulating (less than 0.6 mA) to the PVN of rats, we found that LFnu and HFnu changed correspondingly but recovered after the stimulation. When the PVN of the rats was injured, the RR intervals were enhanced with the rats’ unilaterally or bilaterally injured PVN, especially the bilateral lesion. Meanwhile, LFnu, LF/HF and SDNN decreased gradually, accompanied with an increase of HFnu levels. So these PVN changes may indicate alterations of the sympathovagal balance. Show more

Keywords: Heart rate variability (HRV), paraventricular nucleus (PVN), Rat, electrical lesion

DOI: 10.3233/BME-151338

Citation: Bio-Medical Materials and Engineering, vol. 26, no. s1, pp. S487-S495, 2015

Authors: Du, Yi | Wang, Ling | Li, Shuyu | Zhi, Guang | Li, Deyu | Zhang, Chi

Article Type: Research Article

Abstract: The effects of gender and other contributory factors on pulse waveform are still under arguments. In view of different results caused by few considerations of possible influential factors and general agreement of gender relating to pulse waveform, this study aims to address the confounding factors interfering with the association between gender and pulse waveform characteristics. A novel method was proposed to noninvasively detect pressure pulse wave and assess the morphology of pulse wave. Forty healthy young subjects were included in the present research. Height, weight, systolic blood pressure (SBP), and diastolic blood pressure (DBP) were measured manually and body mass …index (BMI), pulse blood pressure (PP) and heart rate (HR) were calculated automatically. Student’s t test was used to analyze the gender difference and analysis of variance (ANOVA) to examine the effects of intrinsic factors. Univariate regression analysis was performed to assess the main factors on the waveform characteristics. Waveform features were found significantly different between genders. However this study indicates that the main factors for time-related and amplitude-related parameters are HR and SBP respectively. In conclusion, the impact of HR and SBP on pulse waveform features should not be underestimated, especially when analyzing the gender difference. Show more

Keywords: Pressure pulse waveform, gender, heart rate, systolic blood pressure, pulse blood pressure

DOI: 10.3233/BME-151339

Citation: Bio-Medical Materials and Engineering, vol. 26, no. s1, pp. S497-S505, 2015

Authors: Cai, Yongqing | He, Bingwei | Yang, Xiaoxiang | Yao, Jun

Article Type: Research Article

Abstract: Transparent tooth correction treatment is an esthetic alternative to traditional orthodontic treatment. Recently, attachments were introduced in transparent tooth correction treatments to improve the predictability of orthodontic movement. In order to optimize the attachment configuration, the force delivery system of attachments in orthodontic aligner treatment was analyzed. Based on mechanical principles, such as the synthesis theorem of force system, Varignon theorem, and the theorem of force translation, the force system of attachment was analyzed. How the attachments affected the orthodontic treatment was investigated. The attachments’ force system F r , …F t , M r and M t was determined. The optimum attachment for translation and controlled tipping movement was conceived. The attachments can be designed and placed appropriately to improve tooth movement. Show more

Keywords: Optimization configuration, attachments, orthodontic aligner, force system

DOI: 10.3233/BME-151340

Citation: Bio-Medical Materials and Engineering, vol. 26, no. s1, pp. S507-S517, 2015

Authors: Chen, Aijie | Feng, Xiaoli | Zhang, Yanli | Liu, Ruoyu | Shao, Longquan

Article Type: Research Article

Abstract: To investigate the stress distribution of a severely damaged maxillary anterior tooth restored with a computer-aided design/computer-aided manufacturing (CAD/CAM) glass-fiber post system. Twelve models were fabricated with different alveolar bone levels and cervical dentin wall thicknesses and studied using a two-dimensional finite element method. A force of 100 N was applied to the lingual surface of the crown at 45 degrees, and the maximum von Mises stress was calculated. A higher stress level was observed in the dentin than in the post and crown. With the reduction of dentin thickness, the maximum von Mises stress in the dentin increased slightly …to a peak at a thickness of 1.5 mm, followed by a slight decrease at a thickness of 1.0 mm. However, the relative ratio (RR) values did not show a large difference (RR > 80%). Meanwhile, a large difference in RR values was observed with a change in bone level (RR < 80%). When using a CAD/CAM glass-fiber post system, the maximal von Mises stress was significantly affected by the bone level, rather than by the dentin thickness. Moreover, this system may be applied to the treatment of a maxillary anterior tooth with a bone level of only 2/3. Show more

Keywords: computer-aided design/computer-aided manufacturing (CAD/CAM) glass-fiber, finite element analysis, post and core

DOI: 10.3233/BME-151341

Citation: Bio-Medical Materials and Engineering, vol. 26, no. s1, pp. S519-S525, 2015