فهرست مطالب

Medical Signals and Sensors - Volume:9 Issue:1, 2019
  • Volume:9 Issue:1, 2019
  • تاریخ انتشار: 1397/12/27
  • تعداد عناوین: 10
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  • Reza Rasti, Alireza Mehridehnavi *, Hossein Rabbani, Fedra Hajizadeh Pages 1-14
    Background
    Macular disorders, such as diabetic macular edema (DME) and age-related macular degeneration (AMD) are among the major ocular diseases. Having one of these diseases can lead to vision impairments or even permanent blindness in a not-so-long time span. So, the early diagnosis of these diseases are the main goals of eye researchers.
    Material and Methods
    The present study is designed in order to present a comparative study on the recent convolutional mixture of experts (CMoE) models for distinguishing normal macular OCT from DME and AMD. For this purpose, we considered three recent CMoE models called Mixture ensemble of convolutional neural networks (MECNN), Multi-scale Convolutional Mixture of Experts (MCME), and Wavelet-based Convolutional Mixture of Experts (WCME) models. For this research study, the models were evaluated on a database of three different macular OCT sets. Two first OCT sets were acquired by Heidelberg imaging systems consisting of 148 and 45 subjects respectively and set3 was constituted of 384 Bioptigen OCT acquisitions. To provide better performance insight into the CMoE ensembles, we extensively analyzed the models based on the 5-fold cross-validation method and various classification measures such as precision and average area under the ROC curve (AUC).
    Results
    Experimental evaluations showed that the MCME and WCME outperformed the ME-CNN model and presented overall precisions of 98.14% and 96.06% for aligned OCTs respectively. For non-aligned retinal OCTs, these values were 93.95% and 95.56%.
    Conclusion
    Based on the comparative analysis, although the MCME model outperformed the other CMoE models in the analysis of aligned retinal OCTs, the WCME offers a robust model for diagnosis of non-aligned retinal OCTs. This allows having a fast and robust computer aided system in macular OCT imaging which does not rely on the routine computerized processes such as denoising, segmentation of retinal layers, and also retinal layers alignment.
    Keywords: Computer-aided diagnosis system, convolutional mixture of experts, diagnosis, ensemble learning, macular diseases, optical coherence tomography
  • Armin Allahverdy, Alireza Khorrami Moghaddam, Sarah Rahbar, Sadjad Shafiekhani, Hamid Reza Mirzaie, Saeid Amanpour, Yasaman Etemadi, Jamshid Hadjati, Amir Homayoun Jafari * Pages 15-23
    Purpose
    To predict the behavior of biological systems, mathematical models of biological systems have been shown to be useful. In particular, mathematical models of tumor-immune system interactions have demonstrated promising results in prediction of different behaviors of tumor against the immune system.
    Materials and Methods
    This study aimed at the introduction of a new model of tumor-immune system interaction, which includes tumor and immune cells as well as myeloid-derived suppressor cells (MDSCs). MDSCs are immune suppressor cells that help the tumor cells to escape the immune system. The structure of this model is agent-based which makes possible to investigate each component as a separate agent. Moreover, in this model, the effect of low dose 5-fluorouracil (5-FU) on MDSCs depletion was considered.
    Results
    Based on the findings of this study, MDSCs had suppressive effect on increment of immune cell number which consequently result in tumor cells escape the immune cells. It has also been demonstrated that low-dose 5-FU could help immune system eliminate the tumor cells through MDSCs depletion.
    Conclusions
    Using this new agent-based model, multiple injection of low-dose 5-FU could eliminate MDSCs and therefore might have the potential to be considered in treatment of cancers.
    Keywords: 5-fluorouracil, agent-based model, immune-tumor interaction, myeloid-derived suppressor cell
  • Hadi Ghasemifard, Hamid Behnam *, Jahan Tavakkoli Pages 24-32
    Background
    The main goal of ultrasound therapy is to have clinical effects in the tissue without damage to the intervening and surrounding tissues. Treatments have been developed for both in vitro and in clinical applications. HIFU therapy is one of these. Non-invasive surgeries, such as HIFU, have been developed to treat tumors or to stop bleeding. In this approach, an adequate imaging method for monitoring and controlling the treatment is required.
    Methods
    In this paper, an adaptive compressive sensing representation of ultrasound RF echo signals is presented based on empirical mode decomposition (EMD). According to the different numbers of intrinsic mode functions (IMFs) produced by the EMD, the ultrasound signals is adaptively compressive sampled in the source and then adaptively reconstructed in the receiver domains. In this paper, a new application of compressive sensing based on EMD (CSEMD) in the monitoring of high-intensity focused ultrasound (HIFU) treatment is presented. Non-invasive surgeries such as HIFU have been developed for various therapeutic applications. In this technique, a suitable imaging method is necessary for monitoring of the treatment to achieve adequate treatment safety and efficacy. So far, several methods have been proposed, such as ultrasound radiofrequency (RF) signal processing techniques, and imaging methods such as X-ray, MRI, and ultrasound to monitor HIFU lesions.
    Results
    In this paper, a CS-EMD method is used to detect the HIFU thermal lesion dimensions using different types of wavelet transform. The results of the processing on the real data demonstrate the potential for this technique in image-guided HIFU therapy.
    Conclusions
    In this study, a new application of compressive sensing in the field of monitoring of the HIFU treatment is presented. To the best of our knowledge, so far no studies on compressive sensing have been carried out in the monitoring of the HIFU. Based on the results obtained, it was showed that the number of measurements and Intrinsic Mode Functions have the function of noise reduction. Moreover, it was shown that the successful reconstruction of the CS signals can be achieved using a threshold based algorithm. To this end, in this work it was shown that by selecting an appropriate number of measurements, the sparse transform, and a thresholding algorithm, we can achieve a more accurate detection of the HIFU thermal lesion size.
    Keywords: Compressive sensing, empirical mode decomposition, high-intensity focused ultrasound, radiofrequency signal, sparse representation, wavelet transform
  • Farnoosh Pahlevanzadeh, Mehdi Ebrahimian, Hosseinabadi * Pages 33-41
    Introduction
    The aim of this study was to make a bioactive bone cement based on poly (methyl methacrylate) (PMMA) with suitable mechanical properties.
    Materials and Methods
    PMMA has been modified by fabricating a composite consisting of biphasic calcium phosphate (BCP) 68 wt%, PMMA 31 wt% and graphene (Gr) 1 wt% (PMMA/BCP/Gr), 32 wt% of PMMA, and 68 wt% of BCP (PMMA/BCP) and pure PMMA by milling, mixing with monomer liquid, and casting. The modified cements were evaluated regarding mechanical properties, bioactivity, degradation rate, and biocompatibility.
    Results and Discussion
    The scanning electron microscopy (SEM) images of hydroxyapatite (HA) formed on samples surface after 28 days of immersion in simulated body fluid (SBF) demonstrated that bioactivity was obtained due to the addition of BCP, and the degradation rate of the cement was enhanced as well. Investigations of mechanical properties revealed that BCP increased the elastic modulus of PMMA more than 1.5 times, but predictably decreased elongation. The addition of 1 wt% Gr increased elongation and yield strength from 16.39% ± 1.02% and 61.67 ± 1.52 Mpa for PMMA/BCP to 35.18% ± 2.42% and 78.40 ± 2.06 Mpa for PMMA/BCP/Gr, respectively. MG63 cells survival and proliferation improved from 127.55% ± 7.03% for PMMA to 201.41% ± 10.7% for PMMA/BCP/Gr on Day 4 of culture.
    Conclusion
    According to the obtained results of mechanical and biological tests, it seems that new PMMA/BCP/Gr bone cement has a potentiality for usage in orthopedic applications.
    Keywords: Bioactivity, biphasic calcium phosphate, bone cement, graphene, poly (methyl methacrylate)
  • Anita Ebrahimpour, Seyed Salman Zakariaee, Marjaneh Hejazi * Pages 42-49
    Background
    Molecular fluorescence imaging is widely used as a noninvasive method to study the cellular and molecular mechanisms. In the optical imaging system, the sensitivity is the change of the intensity received by the detector for the changed optical characteristics (fluorescence) in each sample point. Sensitivity could be considered as a function of imaging geometry. A favor imaging system has a uniform and high-sensitivity coefficient for each point of the sample. In this study, a new parameter was proposed which the optimal angle between the source and detector could be determined based on this parameter.
    Materials and Methods
    For evaluation of the new method, a two-dimensional mesh with a radius of 20 mm and 5133 nodes was built. In each reconstruction, 0.5-mm fluorescence heterogeneity with a contrast-to-background ratio of fluorescence yield of 10 was randomly added at different points of the sample. The source and the detector were simulated in different geometric conditions. The calculations were performed using the NIRFAST and MATLAB software. The relationship between mean squared error (MSE) and sensitivity uniformity ratio (SUR) was evaluated using the correlation coefficient. Finally, based on the new index, an optimal geometrical strategy was introduced.
    Results
    There was a negative correlation coefficient (R = -0.78) with the inverse relationship between the SUR and MSE indices. The reconstructed images showed that the better image quality achieved using the optimal geometry for all scanning depths. For the conventional geometry, there is an artifact in the opposite side of the inhomogeneity at the shallow depths, which has been eliminated in the reconstructed images achieved using the optimal geometry.
    Conclusion
    The SUR is a powerful computational tool which could be used to determine the optimal angles between the source and detector for each scanning depth.
    Keywords: Fluorescent molecular tomography, geometry optimization, NIRFAST, sensitivity matrix, sensitivity uniformity ratio
  • Ali Ghanjal, Monireh Motaqi, Zahra Arab, Boshra Hatef * Pages 50-58
    Background
    Force variability is related to many kinesiological and neuromuscular properties of the body. This study was conducted to evaluate the effect of type 2 diabetes mellitus (T2DM) and sex on the several fractal and entropy indices of force changing during the repetitive isokinetic exercise of knee flexion-extension.
    Materials and Methods
    Fifty individuals were allowed to participate in the study, and they consist of 18 patients with short-term T2DM, 12 patients with long-term T2DM, and 20 gender/body mass index/ankle imposed to brachial pressure index and physical activity index-matched healthy control (HC) individuals. Torque of knee flexion-extension was recorded for each cycle of 40 isokinetic repetitions at a velocity of 150°/s. The slope across the peak of torques and nonlinear fractal and entropy features in the time series was calculated. Two-way univariate analysis of variance was used to analyze the effect of the groups and gender on the variables.
    Results
    The slope of flexor peak torques was significantly less in the long-term T2DM than the other groups. However, the fractal features such as SD1 and 2 of Poincare plot and fractal dimension katz were significantly decreased in the T2DM groups than the HC and in the women than men. Alpha detrended fluctuation analysis and empirical hurts exponent increased in women of short-term T2DM than men.
    Conclusion
    The force variability decreased in the T2DM as compared to HC and in women as compared to men. However, the randomness of force was significantly increased in women of short-term T2DM.
    Keywords: Force variability, isokinetics, nonlinearity, type 2 diabetes mellitus
  • Hiwa Mohammadi, Mohammad Rezaei, Faezeh Faghihi, Habibolah Khazaie * Pages 59-67
    Objective
    Although insomnia is a sex-dimorphic disorder, there is limited knowledge about the association between sex hormones and insomnia. In the present study, we aimed to investigate the level of hypothalamus-pituitary-gonadal (HPG) axis activity in patients with insomnia by measuring serum levels of luteinizing hormone (LH), follicle stimulating hormone (FSH), 17a-Hydroxyprogesterone, testosterone, progesterone, estradiol, dehydroepiandrosterone sulfate, and sex hormone-binding globulin.
    Materials and Methods
    Numbers of 19 patients; including 13 females (68.4%) with paradox insomnia (32-53 years; 43.2 ± 6.4) and 17 patients; including 8 females (47.1%) with psychophysiological insomnia (14-62 years; 38.4 ± 16.3) were recruited. Seventeen aged-matched normal sleeper consisted of 13 males (26-59 years; 40.7 ± 10) were also recruited as control group. Insomnia was diagnosed by a sleep clinician according to the International Classification of Sleep Disorders-Second Edition criteria and an overnight polysomnography (PSG). A volume of 5 ml of venous blood samples were collected, prepared, and stored at 8 AM under standard condition. Serum levels hormones were measured using enzyme-linked immunosorbent assay kits. Data were analyzed by Chi-square and ANCOVA. Multiple linear regression analysis was used to evaluate the associations between PSG and biochemical parameters.
    Results
    There were no significant differences in all biochemical analyses between two insomnia subgroups (paradoxical and psychophysiological insomnia) and normal sleepers. Testosterone was positively related to maximum pulse transit time (PTT). Moreover, both LH and FSH were positively associated with wake index and diastolic blood pressure.
    Conclusion
    Although there were no significant differences in all HPG's hormones between groups, both LH and FSH were positively associated with wake index and diastolic blood pressure. Moreover, testosterone was positively related to PTT.
    Keywords: Electroencephalographic signal processing, hypothalamic–Pituitary–Gonadal axis, insomnia, polysomnography
  • Farzane Raeisi, Daryoush Shahbazi, Gahrouei *, Elham Raeisi, Esfandiar Heidarian Pages 68-74
    Background
    Breast cancer (BC) remains the leading cause of death in women worldwide, despite the improvements of cancer screening and treatment methods. Recently, development of novel anticancer drugs for the improved prevention and treatment of BC is in the center of research. The anticancer effects of bromelain, as enzyme extract derived from the pineapples, contains chemicals that interfere with the growth of tumor cells. The aim of this study was to evaluate the effect of radiosensitizing of bromelain in 4T1 BC cells.
    Materials and Methods
    This investigation utilized the 3-(4,5-dimethylthiazol-2-yl)-2,5-dimethyltetrazolium bromide assay to characterize the cytotoxicity of bromelain. Colony formation assay used to confirm the ability of bromelain to sensitize BC cells to RT. Flowcytometry performed to define the contribution the apoptosis effect to bromelain mediated radiosensitization of 4T1 cells.
    Results
    Bromelain reduced growth and proliferation of 4T1 cell as a concentration-dependence manner significantly. The survival of 4T1 cancer cells was decreased after combined treatment in a number and size-dependent manner with respect to the control group (P < 0.05). Combination of bromelain with radiation does not influence 4T1 cell apoptosis.
    Conclusion
    The results suggested that bromelain can inhibit the growth and proliferation and reduce survival of 4T1 BC cells and might be used as a candidate radiosensitizer in BC patient.
    Keywords: 4T1, breast cancer, bromelain, radiosensitizing
  • Nahid Chegeni, Amir Hossein Karimi, Iraj Jabbari, Shole Arvandi Page 75
    In the article titled “Photoneutron Dose Estimation in GRID Therapy Using an Anthropomorphic Phantom: A Monte Carlo Study”, published on pages 175-83, Issue 3, Volume 8 of Journal of Medical Signals & Sensors[1], the affiliation of Nahid Chegeni1, Amir Hossein Karimi1 & Shole Arvandi3 is written incorrectly as “1Department of Medical Physics, Jundishapur University of Medical Sciences, Ahvaz, Iran, 3Department of Radiotherapy and Oncology, Jundishapur University of Medical Sciences, Ahvaz, Iran” instead of “1Department of Medical Physics, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran, 3Department of Radiotherapy and Oncology, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran”.
  • Maryam Taghizadeh Dehkordi, Saeed Sadri, Alimohamad Doosthoseini Page 76
    The review article entitled “A Review of Coronary Vessel Segmentation Algorithms” published in Journal of Medical Signals and Sensors, on pages 49-54, Issue 1, Volume 1, 2011[1], has number of unattributed sections of content with high rate of similarity. Plagiarism, unethical publication or redundant publication violates the editorial policy of Journal of Medical Signals and Sensors, which follows best practice guidelines given by the International Committee of Medical Journal Editors (ICMJE) and Committee on Publication Ethics (COPE) mentioned on the Information for Authors and as codified in the signed statements made by the authors regarding the copyright of their work. This article has been retracted as per request made by Editor-in-Chief and Editorial Board of the journal and Authors.