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Biomedical Engineering, IEEE Transactions on

Issue 10  Part 1 • Date Oct. 2011

 This issue contains several parts.Go to:  Part 2 

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Displaying Results 1 - 25 of 32
  • [Front cover]

    Publication Year: 2011 , Page(s): C1
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  • IEEE Transactions on Biomedical Engineering publication information

    Publication Year: 2011 , Page(s): C2
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  • Table of contents

    Publication Year: 2011 , Page(s): 2705 - 2706
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  • EMGTools, an Adaptive and Versatile Tool for Detailed EMG Analysis

    Publication Year: 2011 , Page(s): 2707 - 2718
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1167 KB) |  | HTML iconHTML  

    We have developed an electromyography (EMG) decomposition system called EMGTools that can extract the constituent MUAPs and firing patterns (FPs) for quantitative analysis from the EMG signal recorded at slight effort for clinical evaluation. The aim was to implement a robust system able to handle the challenges and variations in clinically recorded signals. The system extracts MUAPs recorded by concentric needle electrodes and resolves superimposed MUAPs to produce FPs. Thus, critical fixed thresholds/parameters are avoided and replaced with adaptive solutions. The decomposition algorithm consists of three stages: segmentation, clustering, and resolution of compound segments. The results are validated using three different methods, comparing mean MUAP duration with previous methods, comparing dual channel recordings, and assessing the residual signal after decomposition. The advantages and limitations of the system are discussed. View full abstract»

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  • In Vivo and Real-Time Measurement of Magnetic Nanoparticles Distribution in Animals by Scanning SQUID Biosusceptometry for Biomedicine Study

    Publication Year: 2011 , Page(s): 2719 - 2724
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (677 KB) |  | HTML iconHTML  

    Magnetic nanoparticles have been widely applied to biomagnetism, such as drug deliver, magnetic labeling, and contrast agent for in vivo image, etc. To localize the distribution of these magnetic particles in living organism is the first important issue to confirm the effects of magnetic nanoparticles and also evaluate the possible untoward effects. In this study, a scanning high Tc rf-SQUID superconducting quantum interference devices (SQUIDs) biosusceptometry, composed of static SQUID unit and scanning coil sets, is developed for biomedicine study with the advantages of easy operation and unshielded environment. The characteristics tests showed that the system had the low noise of 8 pT/Hz at 400 Hz and the high sensitivity with the minimum detectable magnetization around 4.5 × 10-3 EMU at distance of 13 mm. A magnetic nanoparticle detection test, performed by ex vivo scanning of the magnetic fluids filled capillary under swine skin for simulation of blood vessels in living bodies, confirmed that the system is feasible for dynamic tracking of magnetic nanoparticles. Based on this result, we performed further studies in rats to clarify the dynamic distribution of magnetic nanoparticle in living organism for the pharmacokinetics analysis like drug delivers, and propose the possible physiological metabolism of intravenous magnetic nanoparticles. View full abstract»

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  • Theoretical Modeling and Experimental High-Speed Imaging of Elongated Vocal Folds

    Publication Year: 2011 , Page(s): 2725 - 2731
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (712 KB) |  | HTML iconHTML  

    In this paper, the role of vocal fold elongation in governing glottal movement dynamics was theoretically and experimentally investigated. A theoretical model was first proposed to incorporate vocal fold elongation into the two-mass model. This model predicted the direct and nondirect components of the glottal time series as a function of vocal fold elongation. Furthermore, high-speed digital imaging was applied in excised larynx experiments to visualize vocal fold vibrations with variable vocal fold elongation from -10% to 50% and subglottal pressures of 18- and 24-cm H2O. Comparison between theoretical model simulations and experimental observations showed good agreement. A relative maximum was seen in the nondirect component of glottal area, suggesting that an optimal elongation could maximize the vocal fold vibratory power. However, sufficiently large vocal fold elongations caused the nondirect component to approach zero and the direct component to approach a constant. These results showed that vocal fold elongation plays an important role in governing the dynamics of glottal area movement and validated the applicability of the proposed theoretical model and high-speed imaging to investigate laryngeal activity. View full abstract»

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  • Attenuation of Eye Movements Evoked by a Vestibular Implant at the Frequency of the Baseline Pulse Rate

    Publication Year: 2011 , Page(s): 2732 - 2739
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (518 KB) |  | HTML iconHTML  

    We are developing a vestibular implant to electrically stimulate vestibular neurons in the semicircular canals in order to alleviate vertigo, which is a commonly occurring problem. However, since electrical stimulation causes synchronous (phase-locked) neural responses, such electrical stimulation might also cause inappropriate vestibuloocular eye movements, which might, in turn, cause visual blurring. We investigated the eye movements evoked in the guinea pig using electric stimulation with a constant rate of 250 pulses per second (pps), and measured 0.010° peak-to-peak eye movements on an average at 250 Hz, with an average peak velocity amplitude of 8.1°/s, which might cause visual blurring. However, after half an hour of stimulation, that component reduced to 1.6°/s (0.0020° peak-to-peak). The average time constant for this reduction was 5.0 min. After one week of constant stimulation, the 250-Hz response component was only slightly smaller, at 1.2°/s (0.0015° peak-to-peak). We conclude that although an electrical prosthesis with a resting rate of 250 pps may cause some visual blurring when first turned on, such blurring is very likely to attenuate and be imperceptible within several minutes. View full abstract»

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  • Local Exposure System for Rats Head Using a Figure-8 Loop Antenna in 1500-MHz Band

    Publication Year: 2011 , Page(s): 2740 - 2747
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1212 KB) |  | HTML iconHTML  

    Cellular phones are used in the vicinity of the human head, resulting in localized exposure to this part of the body. To simulate exposure during cellular phone use, microwave energy absorption should be focused within the head region of laboratory animals. In this paper, we developed an exposure system using a figure-8 loop antenna to permit localized exposure of a rat head to 1500-MHz microwave fields, simulating human head exposure to cellular phones. We have numerically estimated the specific absorption rate (SAR) in a rat exposed to microwave fields via our new exposure system. The high ratio of SAR averaged over the target tissue (i.e., the brain) to that averaged over the whole body suggests that the figure-8 antenna can realize greater localized exposure than the previously used exposure system. We have also confirmed the effectiveness of our proposed system experimentally. View full abstract»

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  • Life-Threatening Arrhythmia Verification in ICU Patients Using the Joint Cardiovascular Dynamical Model and a Bayesian Filter

    Publication Year: 2011 , Page(s): 2748 - 2757
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (766 KB) |  | HTML iconHTML  

    In this paper, a novel nonlinear joint dynamical model is presented, which is based on a set of coupled ordinary differential equations of motion and a Gaussian mixture model representation of pulsatile cardiovascular (CV) signals. In the proposed framework, the joint interdependences of CV signals are incorporated by assuming a unique angular frequency that controls the limit cycle of the heart rate. Moreover, the time consequence of CV signals is controlled by the same phase parameter that results in the space dimensionality reduction. These joint equations together with linear assignments to observation are further used in the Kalman filter structure for estimation and tracking. Moreover, we propose a measure of signal fidelity by monitoring the covariance matrix of the innovation signals throughout the filtering procedure. Five categories of life-threatening arrhythmias were verified by simultaneously tracking the signal fidelity and the polar representation of the CV signal estimations. We analyzed data from Physiobank multiparameter databases (MIMIC I and II). Performance evaluation results demonstrated that the sensitivity of the detection ranges over 93.50% and 100.00%. In particular, the addition of more CV signals improved the positive predictivity of the proposed method to 99.27% for the total arrhythmic types. The method was also used for false arrhythmia suppression issued by ICU monitors, with an overall false suppression rate reduced from 42.3% to 9.9%. In addition, false critical ECG arrhythmia alarm rates were found to be, on average, 42.3%, with individual rates varying between 16.7% and 86.5%. The results illustrate that the method can contribute to, and enhance the performance of clinical life-threatening arrhythmia detection. View full abstract»

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  • Optical 3-D Metric Measurements of Local Vocal Fold Deformation Characteristics in an In Vitro Setup

    Publication Year: 2011 , Page(s): 2758 - 2766
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (663 KB) |  | HTML iconHTML  

    Understanding vocal fold dynamics presents an essential part in treating voice disorders as it is the prerequisite to appropriate medical therapy. Various physical and numerical models exist for simulation purposes, all relying on simplified material parameters. To improve current approaches, data of realistic tissue behavior, i.e., in natural surroundings, have to be considered in model development. An in vitro setup was proposed for tensile tests combined with an optical method for precise, local and metrical 3-D measurements of distinctive surface points. Compared to previous 3-D reconstruction methods, the accuracy was improved tenfold. Vertically applied forces versus resulting deformation were measured for ten porcine vocal folds. Deformation characteristics of mucosa and the two-layer structure of mucosa and muscle (MM) were investigated at three distinctive locations along the vocal fold edge. The spring rates were represented by an exponential function. For equal deflections, an increasing spring rate from posterior to anterior for MM was measured. For solely mucosa, the spring rate decreased from the posterior to the middle and subsequently increased again. The MM-layer presented a stiffer deformation behavior than mucosa. For deformations higher than 1.5 mm, the spring rates for MM were more than twice as high as for mucosa. The investigations display the importance of considering both multilayers and local differences for the improvement of vocal fold models. View full abstract»

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  • Substitute Voice Production: Quantification of PE Segment Vibrations Using a Biomechanical Model

    Publication Year: 2011 , Page(s): 2767 - 2776
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1076 KB) |  | HTML iconHTML  

    After total larynx excision due to laryngeal cancer, the tracheoesophageal substitute tissue vibrations at the intersection between the pharynx and the esophagus [pharyngoesophageal segment (PE segment)] serve as voice generator. The quality of the substitute voice significantly depends on the vibratory characteristics of the PE segment. For improving voice rehabilitation, the relationship between the PE dynamics and the resulting substitute voice quality is a matter of particular interest. Precondition for a comprehensive analysis of this relationship is an objective quantification of the PE vibrations. For quantification purposes, a method is proposed, which is based on the reproduction of the tissue vibrations by means of a biomechanical model of the PE segment. An optimization procedure for an automatic determination of appropriate model parameters is suggested to adapt the model dynamics to tissue movements extracted from high-speed (HS) videos. The applicability of the optimization procedure is evaluated with ten synthetic data sets. A mean error of 8.2% for the determination of previously defined model parameters was achieved as well as an overall stability of 7.1%. The application of the model to six HS recordings presented a mean correlation of the vibration patterns of 82%. View full abstract»

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  • Detection of Small Bowel Polyps and Ulcers in Wireless Capsule Endoscopy Videos

    Publication Year: 2011 , Page(s): 2777 - 2786
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (829 KB) |  | HTML iconHTML  

    Over the last decade, wireless capsule endoscopy (WCE) technology has become a very useful tool for diagnosing diseases within the human digestive tract. Physicians using WCE can examine the digestive tract in a minimally invasive way searching for pathological abnormalities such as bleeding, polyps, ulcers, and Crohn's disease. To improve effectiveness of WCE, researchers have developed software methods to automatically detect these diseases at a high rate of success. This paper proposes a novel synergistic methodology for automatically discovering polyps (protrusions) and perforated ulcers in WCE video frames. Finally, results of the methodology are given and statistical comparisons are also presented relevant to other works. View full abstract»

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  • Induction of Electric Field in Human Bodies Moving Near MRI: An Efficient BEM Computational Procedure

    Publication Year: 2011 , Page(s): 2787 - 2793
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (567 KB) |  | HTML iconHTML  

    A computational procedure, based on the boundary element method, has been developed in order to evaluate the electric field induced in a body that moves in the static field around an MRI system. A general approach enables us to investigate rigid translational and rotational movements with any change of motion velocity. The accuracy of the computations is validated by comparison with analytical solutions for simple shaped geometries. Some examples of application of the proposed procedure in the case of motion around an MRI scanner are finally presented. View full abstract»

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  • Application of Independent Component Analysis With Adaptive Density Model to Complex-Valued fMRI Data

    Publication Year: 2011 , Page(s): 2794 - 2803
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (891 KB) |  | HTML iconHTML  

    Independent component analysis (ICA) has proven quite useful for the analysis of real world datasets such as functional resonance magnetic imaging (fMRI) data, where the underlying nature of the data is hard to model. It is particularly useful for the analysis of fMRI data in its native complex form since very little is known about the nature of phase. Phase information has been discarded in most analyses as it is particularly noisy. In this paper, we show that a complex ICA approach using a flexible nonlinearity that adapts to the source density is the more desirable one for performing ICA of complex fMRI data compared to those that use fixed nonlinearity, especially when noise level is high. By adaptively matching the underlying fMRI density model, the analysis performance can be improved in terms of both the estimation of spatial maps and the task-related time courses, especially for the estimation of phase of the time course. We also define a procedure for analysis and visualization of complex-valued fMRI results, which includes the construction of bivariate t-maps for multiple subjects and a complex-valued ICASSO scheme for evaluating the consistency of ICA algorithms. View full abstract»

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  • Determining Energy Expenditure From Treadmill Walking Using Hip-Worn Inertial Sensors: An Experimental Study

    Publication Year: 2011 , Page(s): 2804 - 2815
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1523 KB) |  | HTML iconHTML  

    We describe an experimental study to estimate energy expenditure during treadmill walking using a single hip-mounted inertial sensor (triaxial accelerometer and triaxial gyroscope). Typical physical-activity characterization using commercial monitors use proprietary counts that do not have a physically interpretable meaning. This paper emphasizes the role of probabilistic techniques in conjunction with inertial data modeling to accurately predict energy expenditure for steady-state treadmill walking. We represent the cyclic nature of walking with a Fourier transform and show how to map this representation to energy expenditure ([(V)dot]O2, mL/min) using three regression techniques. A comparative analysis of the accuracy of sensor streams in predicting energy expenditure reveals that using triaxial information leads to more accurate energy-expenditure prediction compared to only using one axis. Combining accelerometer and gyroscope information leads to improved accuracy compared to using either sensor alone. Nonlinear regression methods showed better prediction accuracy compared to linear methods but required an order of higher magnitude run time. View full abstract»

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  • Real-Time Multimodal Retinal Image Registration for a Computer-Assisted Laser Photocoagulation System

    Publication Year: 2011 , Page(s): 2816 - 2824
    Cited by:  Papers (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (679 KB) |  | HTML iconHTML  

    An algorithm for the real-time registration of a retinal video sequence captured with a scanning digital ophthal moscope (SDO) to a retinal composite image is presented. This method is designed for a computer-assisted retinal laser photocoagulation system to compensate for retinal motion and hence enhance the accuracy, speed, and patient safety of retinal laser treatments. The procedure combines intensity and feature-based registration techniques. For the registration of an individual frame, the translational frame-to-frame motion between preceding and current frame is detected by normalized cross correlation. Next, vessel points on the current video frame are identified and an initial transformation estimate is constructed from the calculated translation vector and the quadratic registration matrix of the previous frame. The vessel points are then iteratively matched to the segmented vessel centerline of the composite image to refine the initial transformation and register the video frame to the composite image. Criteria for image quality and algorithm convergence are introduced, which assess the exclusion of single frames from the registration process and enable a loss of tracking signal if necessary. The algorithm was successfully applied to ten different video sequences recorded from patients. It revealed an average accuracy of 2.47 ±2.0 pixels ( ~ 23.2 ±18.8 μm) for 2764 evaluated video frames and demonstrated that it meets the clinical requirements. View full abstract»

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  • A Novel Phase Congruency Based Algorithm for Online Data Reduction in Ambulatory EEG Systems

    Publication Year: 2011 , Page(s): 2825 - 2834
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1354 KB) |  | HTML iconHTML  

    Real signals are often corrupted by noise with a power spectrum variable over time. In applications involving these signals, it is expected that dynamically estimating and correcting for this noise would increase the amount of useful information extracted from the signal. One such application is scalp EEG monitoring in epilepsy, where electrical activity generated by cranio-facial muscles obscure the measured brainwaves. This paper presents a data-selection algorithm based on phase congruency to identify interictal spikes from background EEG; together with a novel statistical method that allows a more comprehensive trade-off based quantitative comparison of two algorithms which have been tested at a fixed threshold in the same database. Here, traditional phase congruency has been modified to incorporate a dynamic estimate of muscle activity present in the input scalp EEG signal. The proposed algorithm achieves 50% data reduction whilst detecting more than 80% of interictal spikes. This represents a significant improvement over the state-of-the-art denoising method for phase congruency. View full abstract»

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  • Maternal MCG Interference Cancellation Using Splined Independent Component Subtraction

    Publication Year: 2011 , Page(s): 2835 - 2843
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (783 KB) |  | HTML iconHTML  

    Signal distortion is commonly observed when using independent component analysis (ICA) to remove maternal cardiac interference from the fetal magnetocardiogram. This can be seen even in the most conservative case where only the independent components dominated by maternal interference are subtracted from the raw signal, a procedure we refer to as independent component subtraction (ICS). Distortion occurs when the subspaces of the fetal and maternal signals have appreciable overlap. To overcome this problem, we employed splining to remove the fetal signal from the maternal source component. The maternal source components were downsampled and then interpolated to their original sampling rate using a cubic spline. A key aspect of the splining procedure is that the maternal QRS complexes are downsampled much less than the rest of the maternal signal so that they are not distorted, despite their higher bandwidth. The splined maternal source components were projected back onto the magnetic field measurement space and then subtracted from the raw signal. The method was evaluated using data from 24 subjects. We compared the results of conventional, i.e., unsplined, ICS with our method, splined ICS, using matched filtering as a reference. Correlation and subjective assessment of the P-wave and QRS complex were used to assess the performance. Using ICS, we found that the P-wave was adversely affected in 7 of 24 (29%) subjects, all having correlations less than 0.8. Splined ICS showed negligible distortion and improved the signal fidelity to some extent in all subjects. We also demonstrated that maternal T-wave interference could be problematic when the fetal and maternal heartbeats were synchronous. In these instances, splined ICS was more effective than matched filtering. View full abstract»

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  • Adaptive Phase Extraction: Incorporating the Gabor Transform in the Matching Pursuit Algorithm

    Publication Year: 2011 , Page(s): 2844 - 2851
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (631 KB) |  | HTML iconHTML  

    Short-time Fourier transform (STFT), Gabor transform (GT), wavelet transform (WT), and the Wigner-Ville distribution (WVD) are just some examples of time-frequency analysis methods which are frequently applied in biomedical signal analysis. However, all of these methods have their individual drawbacks. The STFT, GT, and WT have a time-frequency resolution that is determined by algorithm parameters and the WVD is contaminated by cross terms. In 1993, Mallat and Zhang introduced the matching pursuit (MP) algorithm that decomposes a signal into a sum of atoms and uses a cross-term free pseudo-WVD to generate a data-adaptive power distribution in the time-frequency space. Thus, it solved some of the problems of the GT and WT but lacks phase information that is crucial e.g., for synchronization analysis. We introduce a new time-frequency analysis method that combines the MP with a pseudo-GT. Therefore, the signal is decomposed into a set of Gabor atoms. Afterward, each atom is analyzed with a Gabor analysis, where the time-domain Gaussian window of the analysis matches that of the specific atom envelope. A superposition of the single time-frequency planes gives the final result. This is the first time that a complete analysis of the complex time-frequency plane can be performed in a fully data-adaptive and frequency-selective manner. We demonstrate the capabilities of our approach on a simulation and on real-life magnetoencephalogram data. View full abstract»

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  • Measurement of Lung Hyperelastic Properties Using Inverse Finite Element Approach

    Publication Year: 2011 , Page(s): 2852 - 2859
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1075 KB) |  | HTML iconHTML  

    Hyperelastic properties of deflated lung tissue have been characterized via an inverse finite element approach. Such properties are useful in many medical diagnosis and treatment applications where tissue deformation can be modeled to account for during the procedure. Several indentation experiments were conducted on various porcine lungs' tissue specimens resected immediately from different regions and lobes after the animals were sacrificed. Three different strain energy models, namely Ogden, Yeoh, and Polynomial, were used and respective hyperelastic parameters were obtained. The parameters for each model were estimated through an optimization process where the experimental force-displacement profiles of indentation were fitted to those obtained from finite element simulations performed specifically for the samples' geometries. Results obtained in this investigation for all the three models indicate convergence with reasonably low average fitting errors ranging from 2.3% to 6.2%. Independent tests were also performed to assess the effects of samples' heterogeneities on the obtained parameters. The outcome of these tests was encouraging and confirmed small impact of tissue inhomogeneities on the estimated parameters. The reported hyperelastic properties can, accordingly, pave the way for more accurate biomechanical modeling of the lung's soft tissue in the emerging applications of minimally invasive medical intervention for lung cancer diagnosis and treatment. View full abstract»

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  • Case for Applying Subnanosecond High-Intensity, Electrical Pulses to Biological Cells

    Publication Year: 2011 , Page(s): 2860 - 2866
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (762 KB) |  | HTML iconHTML  

    In this paper, model analysis into the time-dependent transmembrane potential at the outer cell membrane is presented, for applied high-intensity electric pulses having durations in the nanosecond range or smaller. It is argued that the frequency-dependent dielectric response of cell membranes could be used to advantage for stronger bioeffects by employing shorter pulses. Our model calculations predict faster transmembrane voltages and larger electroporation densities for a given external energy with pulse durations in the subnanosecond regime. This temporal regime would be used, for example, in the electrotherapy of mixed cell ensembles having different dielectric response properties. View full abstract»

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  • Continuous Locomotion-Mode Identification for Prosthetic Legs Based on Neuromuscular–Mechanical Fusion

    Publication Year: 2011 , Page(s): 2867 - 2875
    Cited by:  Papers (24)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (656 KB) |  | HTML iconHTML  

    In this study, we developed an algorithm based on neuromuscular-mechanical fusion to continuously recognize a variety of locomotion modes performed by patients with transfemoral (TF) amputations. Electromyographic (EMG) signals recorded from gluteal and residual thigh muscles and ground reaction forces/moments measured from the prosthetic pylon were used as inputs to a phase-dependent pattern classifier for continuous locomotion-mode identification. The algorithm was evaluated using data collected from five patients with TF amputations. The results showed that neuromuscular-mechanical fusion outperformed methods that used only EMG signals or mechanical information. For continuous performance of one walking mode (i.e., static state), the interface based on neuromuscular-mechanical fusion and a support vector machine (SVM) algorithm produced 99% or higher accuracy in the stance phase and 95% accuracy in the swing phase for locomotion-mode recognition. During mode transitions, the fusion-based SVM method correctly recognized all transitions with a sufficient predication time. These promising results demonstrate the potential of the continuous locomotion-mode classifier based on neuromuscular-mechanical fusion for neural control of prosthetic legs. View full abstract»

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  • A Numerical Investigation of Breast Compression: A Computer-Aided Design Approach for Prescribing Boundary Conditions

    Publication Year: 2011 , Page(s): 2876 - 2884
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (760 KB) |  | HTML iconHTML  

    Prior to performing an MRI-guided breast biopsy, the radiologist has to locate the suspect lesion with the breast compressed between rigid plates. However, the suspect lesion is typically identified from a diagnostic MRI exam with the breast hanging freely under the force of gravity. There are several challenges associated with localizing suspect lesions including, patient positioning, the visibility of the lesion may fade after contrast injection, menstrual cycles, and lesion deformation. Researchers have developed finite element analysis (FEA) methodologies that simulate breast compression with the intent of reducing these challenges. In this paper, we constructed a patient-specific finite element (FE) breast model from diagnostic MR images. In addition, we constructed surfaces corresponding to the biopsy MR volume and used them to deform the FE breast mesh. The predicted results suggest that the FE breast model, in its uncompressed configuration, can be compressed to replicate the perimeter of the biopsy MR volume. The simulated lesion displacement was within 3 mm of its actual position. View full abstract»

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  • GGO Nodule Volume-Preserving Nonrigid Lung Registration Using GLCM Texture Analysis

    Publication Year: 2011 , Page(s): 2885 - 2894
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (682 KB) |  | HTML iconHTML  

    In lung cancer screening, benign and malignant nodules can be classified through nodule growth assessment by the registration and, then, subtraction between follow-up computed tomography scans. During the registration, the volume of nodule regions in the floating image should be preserved, whereas the volume of other regions in the floating image should be aligned to that in the reference image. However, ground glass opacity (GGO) nodules are very elusive to automatically segment due to their inhomogeneous interior. In other words, it is difficult to automatically define the volume-preserving regions of GGO nodules. In this paper, we propose an accurate and fast nonrigid registration method. It applies the volume-preserving constraint to candidate regions of GGO nodules, which are automatically detected by gray-level cooccurrence matrix (GLCM) texture analysis. Considering that GGO nodules can be characterized by their inner inhomogeneity and high intensity, we identify the candidate regions of GGO nodules based on the homogeneity values calculated by the GLCM and the intensity values. Furthermore, we accelerate our nonrigid registration by using Compute Unified Device Architecture (CUDA). In the nonrigid registration process, the computationally expensive procedures of the floating-image transformation and the cost-function calculation are accelerated by using CUDA. The experimental results demonstrated that our method almost perfectly preserves the volume of GGO nodules in the floating image as well as effectively aligns the lung between the reference and floating images. Regarding the computational performance, our CUDA-based method delivers about 20× faster registration than the conventional method. Our method can be successfully applied to a GGO nodule follow-up study and can be extended to the volume-preserving registration and subtraction of specific diseases in other organs (e.g., liver cancer). View full abstract»

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  • Rupture Status Discrimination in Intracranial Aneurysms Using the Centroid–Radii Model

    Publication Year: 2011 , Page(s): 2895 - 2903
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1066 KB) |  | HTML iconHTML  

    Intracranial aneurysms are localized, abnormal arterial dilatations with a variable risk of rupture, leading to medical conditions associated with high morbidity and mortality. Predicting their risk of rupture, especially for incidental asymptomatic aneurysms, is a challenging task. The size of the aneurysm sac is traditionally used to assess the risk, but shape analysis has emerged as a promising differentiator of rupture likelihood. The centroid-radii model (CRM) is introduced here to describe both the size and the shape of the aneurysms, and determine rupture status. The entropy of CRM is proposed as an aneurysm descriptor which is easy to compute, robust to noise and segmentation, and accurate in rupture status discrimination. Analysis is performed on 154 patient-derived saccular aneurysms. The aneurysms are further classified as sidewall and bifurcation, and the shape analysis is performed separately on the two subtypes. Using the entropy of CRM resulted in 80.3% and 70.5% classification accuracy of status rupture in sidewall and bifurcation aneurysms, respectively. When compared to the accuracy of some commonly used size and shape indexes, the entropy of the CRM proved to be a more accurate single index associated with rupture in intracranial aneurysms, for both sidewall and bifurcation subtypes. View full abstract»

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Aims & Scope

IEEE Transactions on Biomedical Engineering contains basic and applied papers dealing with biomedical engineering. Papers range from engineering development in methods and techniques with biomedical applications to experimental and clinical investigations with engineering contributions.

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Meet Our Editors

Editor-in-Chief
Bin He
Department of Biomedical Engineering