MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'IEEE Transactions on Biomedical Engineering' source. Sun, 14 Mar 2010 16:32:53 +0100 http://www.medworm.com/index.php?rid=3335034&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5419292 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335034 Mon, 01 Mar 2010 00:00:00 +0100 3335034 http://www.medworm.com/index.php?rid=3335033&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5419291 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335033 Mon, 01 Mar 2010 00:00:00 +0100 3335033 http://www.medworm.com/index.php?rid=3335032&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D4895722 In this study, we present a method to investigate the functional connectivity of prefrontal cortex (PFC) Sby applying a Gauss–Markov model to fNIRS signals. The hemodynamic changes on PFC during the performance of cognitive paradigm are measured by fNIRS for 17 healthy adults. The color-word matching Stroop task is performed to activate 16 different regions of PFC. There are three different types of stimuli in this task, which can be listed as incongruent stimulus (IS), congruent stimulus (CS), and neutral stimulus (NS), respectively. We introduce a new measure, called “information transfer metric” (ITM) for each time sample. The behavior of ITMs during IS are significantly different from the ITMs during CS and NS, which is consistent with the outcome of the previous r... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335032 Mon, 01 Mar 2010 00:00:00 +0100 3335032 http://www.medworm.com/index.php?rid=3335031&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D4895277 We present an optimal method for decoding the activity of primary motor cortex (M1) neurons in a nonhuman primate during single finger movements. The method is based on the maximum-likelihood (ML) inference, which assuming the probability of finger movements is uniform, is equivalent to the maximum a posteriori (MAP) inference. Each neuron’s activation is first quantified by the change in firing rate before and after finger movement. We then estimate the probability density function of this activation given finger movement, i.e., Pr(neuronal activation (x)$vert$ finger movements (m)). Based on the ML criterion, we choose finger movements to maximize Pr(x$vert$m). Experimentally, data were collected from 115 task-related neurons in M1 as the monkey performed flexion and extension of ... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335031 Mon, 01 Mar 2010 00:00:00 +0100 3335031 http://www.medworm.com/index.php?rid=3335030&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5282635 Skin burns below ground pads during monopolar RF ablation are increasingly prevalent, thereby hindering the development of higher power RF generators capable of creating larger tumor ablation zones in combination with multiple or new applicators. Our goal was to evaluate reduction in skin temperatures via additional ground pads in an in vivo porcine model. Three ground pads placed on the animal's abdomen were activated either simultaneously or sequentially, where activation timing was adjusted to equilibrate skin temperature below each pad. Thirteen RF ablations ($n$ $=$ 4 simultaneous at 300 W, $n$ $=$ 5 sequential at 300 W, and $n$ $=$ 4 sequential at 375 W) were performed for 12 min via two internally cooled cluster electrodes placed in the gluteus maximus of domestic swine. Tem... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335030 Mon, 01 Mar 2010 00:00:00 +0100 3335030 http://www.medworm.com/index.php?rid=3335029&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5290039 Transbronchial biopsy of peripheral lung nodules is hindered by the inability to access lesions endoluminally due to the large diameter of conventional bronchoscopes. An ultrathin scanning fiber bronchoscope has recently been developed to advance image-guided biopsy several branching generations deeper into the peripheral airways. However, navigating a potentially complex 3-D path to the region of interest presents a challenge to the bronchoscopist. An accompanying guidance system has also been developed to track the bronchoscope through the airways, and display its position and intended path on a virtual display. Intraoperative localization of the bronchoscope was achieved by combining electromagnetic tracking (EMT) and image-based tracking (IBT). An error-state Kalman filter was used to ... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335029 Mon, 01 Mar 2010 00:00:00 +0100 3335029 http://www.medworm.com/index.php?rid=3335028&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D4812080 In conclusion, the rHEA is suitable for upper limb rehabilitation therapy as it matches the desired performance. (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335028 Mon, 01 Mar 2010 00:00:00 +0100 3335028 http://www.medworm.com/index.php?rid=3335027&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D4812084 An adaptive noise canceller was used to reduce the effect of floor vibrations on ballistocardiogram (BCG) measurements from a modified electronic bathroom scale. A seismic sensor was placed next to the scale on the floor and used as the noise reference input to the noise canceller. BCG recordings were acquired from a healthy subject while another person stomped around the scale, thus causing increased floor vibrations. The noise canceller substantially eliminated the artifacts in the BCG signal due to these vibrations without distorting the morphology of the measured BCG. Additionally, recordings were obtained from another subject standing inside a parked bus while the engine was running. The artifacts due to the vibrations of the engine, and the other vehicles moving on the road next to t... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335027 Mon, 01 Mar 2010 00:00:00 +0100 3335027 http://www.medworm.com/index.php?rid=3335026&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5282636 A suspension system for the BiVACOR biventricular assist device (BiVAD) has been developed and tested. The device features two semi-open centrifugal impellers mounted on a common rotating hub. Flow balancing is achieved through the movement of the rotor in the axial direction. The rotor is suspended in the pump casings by an active magnetic suspension system in the axial direction and a passive hydrodynamic bearing in the radial direction. This paper investigates the axial movement capacity of the magnetic bearing system and the power consumption at various operating points. The force capacity of the passive hydrodynamic bearing is investigated using a viscous glycerol solution. Axial rotor movement in the range of $pm$0.15 mm is confirmed and power consumption is under 15.5 W. The journal... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335026 Mon, 01 Mar 2010 00:00:00 +0100 3335026 http://www.medworm.com/index.php?rid=3335025&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5290067 In this paper, we report a theoretical study on magnetoacoustic tomography with magnetic induction (MAT-MI). According to the description of signal generation mechanism using Green's function, the acoustic dipole model was proposed to describe acoustic source excited by the Lorentz force. Using Green's function, three kinds of reconstruction algorithms based on different models of acoustic source (potential energy, vectored acoustic pressure, and divergence of Lorenz force) are deduced and compared, and corresponding numerical simulations were conducted to compare these three kinds of reconstruction algorithms. The computer simulation results indicate that the potential energy method and vectored pressure method can directly reconstruct the Lorentz force distribution and give... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335025 Mon, 01 Mar 2010 00:00:00 +0100 3335025 http://www.medworm.com/index.php?rid=3335024&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D4956994 An algorithm aiming at robust and simultaneous registrations of a sequence of 3-D shapes was recently presented by Jacq et al. [IEEE Trans. Biomed. Eng., vol. 55, no. 5, 2008]. This algorithm has to carry out an implicit representation of their common root shape (RS). A particular emphasis was put on the median consensus shape, which is a specific type of RS. Unlike this previous study, mainly focusing on the algorithm foundations while dealing with very specific applications examples, this paper attempts to show the versatility of the RS concept through a set of three problems involving a wider scope of application. The first problem copes with the design of prosthetic cortical plates for the hip joint. It shows how an explicit reconstruction of the RS, coming with its consensus map, coul... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335024 Mon, 01 Mar 2010 00:00:00 +0100 3335024 http://www.medworm.com/index.php?rid=3335023&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5290066 Colonoscopy is an endoscopic technique that allows a physician to inspect the inside of the human colon. The appearance of the appendiceal orifice during colonoscopy indicates a complete traversal of the colon, which is an important quality indicator of the colon examination. In this paper, we present two new algorithms. The first algorithm determines whether an image shows the clearly seen appendiceal orifice. This algorithm uses our new local features based on geometric shape, illumination difference, and intensity changes along the norm direction (cross section) of an edge. The second algorithm determines whether the video is an appendix video (the video showing at least 3 s of the appendiceal orifice inspection). Such a video indicates good visualization of the appendiceal orifice. Thi... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335023 Mon, 01 Mar 2010 00:00:00 +0100 3335023 http://www.medworm.com/index.php?rid=3335022&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5306167 Computerized tomographic colonography is a minimally invasive technique for the detection of colorectal polyps and carcinoma. Computer-aided diagnosis (CAD) schemes are designed to help radiologists locating colorectal lesions in an efficient and accurate manner. Large lesions are often initially detected as multiple small objects, due to which such lesions may be missed or misclassified by CAD systems. We propose a novel method for automated detection and segmentation of all large lesions, i.e., large polyps as well as carcinoma. Our detection algorithm is incorporated in a classical CAD system. Candidate detection comprises preselection based on a local measure for protrusion and clustering based on geodesic distance. The generated clusters are further segmented and analyzed. The segment... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335022 Mon, 01 Mar 2010 00:00:00 +0100 3335022 http://www.medworm.com/index.php?rid=3335021&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5290064 This paper reports a new structural method to mathematically represent and quantify a tissue for the purpose of automated and objective cancer diagnosis and grading. Unlike the previous structural methods, which quantify a tissue considering the spatial distributions of its cell nuclei, the proposed method relies on the use of distributions of multiple tissue components for the representation. To this end, it constructs a graph on multiple tissue components and colors its edges depending on the component types of their endpoints. Subsequently, it extracts a new set of structural features from these color graphs and uses these features in the classification of tissues. Working with the images of colon tissues, our experiments demonstrate that the color-graph approach leads to 82.65% test ac... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335021 Mon, 01 Mar 2010 00:00:00 +0100 3335021 http://www.medworm.com/index.php?rid=3335020&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5272376 Ultrasound biomicroscopy (UBM) of mice can provide a testing ground for new imaging strategies. The UBM system presented in this paper facilitates the development of imaging and measurement methods with programmable design, arbitrary waveform coding, broad bandwidth (2–80 MHz), digital filtering, programmable processing, RF data acquisition, multithread/multicore real-time display, and rapid mechanical scanning (≤170 frames/s). To demonstrate the capacities of the UBM system, chirp (1.28, 2.56, and 5.12 $mu$ s durations) sequences with matched filter analysis are implemented in real time. Chirp and conventional impulse imaging (31 and 46 MHz center frequencies) of a wire phantom at fast sectorial scanning (0.7 ${^circ}$ $hbox{ms}^{-1}$ , 20 frames/s one-way image rate) are co... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335020 Mon, 01 Mar 2010 00:00:00 +0100 3335020 http://www.medworm.com/index.php?rid=3335019&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5306163 The identification of phenotypic changes in breast cancer (BC) histopathology on account of corresponding molecular changes is of significant clinical importance in predicting disease outcome. One such example is the presence of lymphocytic infiltration (LI) in histopathology, which has been correlated with nodal metastasis and distant recurrence in HER2+ BC patients. In this paper, we present a computer-aided diagnosis (CADx) scheme to automatically detect and grade the extent of LI in digitized HER2+ BC histopathology. Lymphocytes are first automatically detected by a combination of region growing and Markov random field algorithms. Using the centers of individual detected lymphocytes as vertices, three graphs (Voronoi diagram, Delaunay triangulation, and minimum spanning tree) are const... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335019 Mon, 01 Mar 2010 00:00:00 +0100 3335019 http://www.medworm.com/index.php?rid=3335018&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5282633 Continuous glucose monitoring (CGM) devices can be very useful in diabetes management. Unfortunately, their use in online applications, e.g., for hypo/hyperalert generation, is made difficult by random noise measurement. Remarkably, the SNR of CGM data varies with the sensor and with the individual. As a consequence, approaches in which filter parameters are not allowed to adapt to the current SNR are likely to be suboptimal. In this paper, we present a new online methodology to reduce noise in CGM signals by a Kalman filter (KF), whose unknown parameters are adjusted in a given individual by a stochastically based smoothing criterion exploiting data of a burn-in interval. The performance of the new KF approach is quantitatively assessed on Monte Carlo simulations and 24 real CGM datasets.... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335018 Mon, 01 Mar 2010 00:00:00 +0100 3335018 http://www.medworm.com/index.php?rid=3335017&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5272275 Our understanding of etiology of obesity and overweight is incomplete due to lack of objective and accurate methods for monitoring of ingestive behavior (MIB) in the free-living population. Our research has shown that frequency of swallowing may serve as a predictor for detecting food intake, differentiating liquids and solids, and estimating ingested mass. This paper proposes and compares two methods of acoustical swallowing detection from sounds contaminated by motion artifacts, speech, and external noise. Methods based on mel-scale Fourier spectrum, wavelet packets, and support vector machines are studied considering the effects of epoch size, level of decomposition, and lagging on classification accuracy. The methodology was tested on a large dataset (64.5 h with a total of 9966 swallo... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335017 Mon, 01 Mar 2010 00:00:00 +0100 3335017 http://www.medworm.com/index.php?rid=3335016&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5272536 This paper presents a spatiotemporal framework for estimating single-trial response latencies and amplitudes from evoked response magnetoencephalographic/electroencephalographic data. Spatial and temporal bases are employed to capture the aspects of the evoked response that are consistent across trials. Trial amplitudes are assumed independent but have the same underlying normal distribution with unknown mean and variance. The trial latency is assumed to be deterministic but unknown. We assume that the noise is spatially correlated with unknown covariance matrix. We introduce a generalized expectation–maximization algorithm called Trial Variability in Amplitude and Latency ( TriViAL) that computes the maximum likelihood (ML) estimates of the amplitudes, latencies, basis coefficients... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335016 Mon, 01 Mar 2010 00:00:00 +0100 3335016 http://www.medworm.com/index.php?rid=3335015&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D4674624 As in other complex signal processing tasks, ECG beat delineation algorithms are usually constituted of a set of processing modules, each one characterized by a certain number of parameters (filter cutoff frequencies, threshold levels, time windows, etc.). It is well recognized that the adjustment of these parameters is a complex task that is traditionally performed empirically and manually, based on the experience of the designer. In this paper, we propose a new automated and quantitative method to optimize the parameters of such complex signal processing algorithms. To solve this multiobjective optimization problem, an evolutionary algorithm (EA) is proposed. This method for parameter optimization is applied to a wavelet-transform-based ECG delineator that has previously shown interestin... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335015 Mon, 01 Mar 2010 00:00:00 +0100 3335015 http://www.medworm.com/index.php?rid=3335014&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5290084 Cochlear implants stimulate the auditory nerve with the outputs of a bank of narrow-band filters. We propose that cochlear implant users are better able to perceive speech when these frequency bands are desynchronized, as occurs in the normal cochlea. The first part of this study was a computational investigation of across-frequency delays on the stimulation patterns generated by the advanced combination encoder (ACE) sound-processing strategy. By offsetting frequency bands from each other, fewer stimuli were discarded from voiced speech by maxima selection. Background noise, however, was not affected in this way. The second part of this study was an assessment of speech perception with across-frequency delays in cochlear implant users with the ACE strategy. In the perception of sentences ... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335014 Mon, 01 Mar 2010 00:00:00 +0100 3335014 http://www.medworm.com/index.php?rid=3335013&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5289981 For assessment of specific cardiac pathologies, vectorcardiography is generally considered superior with respect to electrocardiography. Existing vectorcardiography methods operate by calculating the vectorcardiogram (VCG) as a fixed linear combination of ECG signals. These methods, with the inverse Dower matrix method the current standard, are therefore not flexible with respect to different body compositions and geometries. Hence, they cannot be applied with accuracy on patients that do not conform to the fixed standard. Typical examples of such patients are obese patients or fetuses. For the latter category, when recording the fetal ECG from the maternal abdomen the distance of the fetal heart with respect to the electrodes is unknown. Consequently, also the signal attenuation/transform... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335013 Mon, 01 Mar 2010 00:00:00 +0100 3335013 http://www.medworm.com/index.php?rid=3335012&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5268215 Optical methods are one of the painless and promising techniques that can be used for blood glucose predictions for diabetes patients. The use of thermally tunable vertical cavity surface-emitting lasers (VCSELs) as the light source to obtain blood absorption spectra, along with the multivariate technique partial least squares for analysis and glucose estimation, has been demonstrated. With further improvements by using data preprocessing and two VCSELs, we have achieved a clinically acceptable level in the physiological range in buffered solutions. The results of previous experiments conducted using white light showed that increasing the number of wavelength intervals used in the analysis improves the accuracy of prediction. The average prediction error, using absorption spectra from one ... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335012 Mon, 01 Mar 2010 00:00:00 +0100 3335012 http://www.medworm.com/index.php?rid=3335011&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5233802 In this paper, we present a quantitative study on the speech fundamental frequency (F0) of the cochlear implant-like spectrally reduced speech (SRS). The SRS was synthesized from the subband amplitude and frequency modulations (AM and FM) of original clean speech utterances selected from the TI-digits database. The SRS synthesis algorithm was derived from the frequency amplitude modulation encoding (FAME) strategy, proposed by Nie et al., 2005. The normalized mses (NMSEs), calculated between the F0 of the original clean speech and that of the SRSs, were analyzed. The NMSEs analysis of F0 revealed the greater F0 distortion in the AM-based SRS, which is the acoustic simulation of present-day cochlear implants, compared to the FAME-based SRS. This evidence supports the fact that current cochl... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335011 Mon, 01 Mar 2010 00:00:00 +0100 3335011 http://www.medworm.com/index.php?rid=3335010&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D4956993 Intramuscular electromyography (EMG) signals are usually decomposed with semiautomatic procedures that involve the interaction with an expert operator. In this paper, a Bayesian statistical model and a maximum a posteriori (MAP) estimator are used to solve the problem of multiunit EMG decomposition in a fully automatic way. The MAP estimation exploits both the likelihood of the reconstructed EMG signal and some physiological constraints, such as the discharge pattern regularity and the refractory period of muscle fibers, as prior information integrated in a Bayesian framework. A Tabu search is proposed to efficiently tackle the nondeterministic polynomial-time-hard problem of optimization w.r.t the motor unit discharge patterns. The method is fully automatic and was tested on simulated and... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335010 Mon, 01 Mar 2010 00:00:00 +0100 3335010 http://www.medworm.com/index.php?rid=3335009&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5290085 With the emerging use of snore properties for clinical purposes, there is a need to understand the characteristics of snore source flow (SF)—the acoustic source in snore production. This paper attempts to analyze and model both SF and its derivative (SFD), along with its preliminary application to the generation of synthetic snores. SFs and SFDs were extracted from natural snores via an iterative adaptive inverse filtering approach, and subsequently parameterized into various time- and amplitude-based parameters to quantify the oscillatory maneuvers of snore excitation source (ES). The SF and SFD waveforms were also, respectively, modeled using the first and second derivatives of the Gaussian probability density function. Subjective and objective measures, including paired compariso... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335009 Mon, 01 Mar 2010 00:00:00 +0100 3335009 http://www.medworm.com/index.php?rid=3335008&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5290091 This paper describes a control architecture and intent recognition approach for the real-time supervisory control of a powered lower limb prosthesis. The approach infers user intent to stand, sit, or walk, by recognizing patterns in prosthesis sensor data in real time, without the need for instrumentation of the sound-side leg. Specifically, the intent recognizer utilizes time-based features extracted from frames of prosthesis signals, which are subsequently reduced to a lower dimensionality (for computational efficiency). These data are initially used to train intent models, which classify the patterns as standing, sitting, or walking. The trained models are subsequently used to infer the user's intent in real time. In addition to describing the generalized control approach, this p... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335008 Mon, 01 Mar 2010 00:00:00 +0100 3335008 http://www.medworm.com/index.php?rid=3335007&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5272277 This study details an approach that characterizes the movements of 68 elderly subjects performing a directed routine of unsupervised physical tasks. The movement characterization is achieved through the use of a triaxial accelerometer. A number of fall-related features, extracted from the accelerometry signals, combined with a linear least squares model, maps to a clinically validated measure of falls risk with a correlation of $rho =0.81$$(p < 0.001)$. (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335007 Mon, 01 Mar 2010 00:00:00 +0100 3335007 http://www.medworm.com/index.php?rid=3335006&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5272413 In this paper, we develop a 3-D adaptive mesh refinement technique. The algorithm is constructed with an electric impedance tomography forward problem and the finite-element method in mind, but is applicable to a much wider class of problems. We use the method to evaluate the distribution of currents injected into a model of a human body through skin contact electrodes. We demonstrate that the technique leads to a significantly improved solution, particularly near the electrodes. We discuss error estimation, efficiency, and quality of the refinement algorithm and methods that allow for preserving mesh attributes in the refinement process. (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335006 Mon, 01 Mar 2010 00:00:00 +0100 3335006 http://www.medworm.com/index.php?rid=3335005&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5306166 The surface electrohysterographic (EHG) signal represents the bioelectrical activity that triggers the mechanical contraction of the uterine muscle. Previous work demonstrated the relevance of the EHG signal analysis for fetal and maternal monitoring as well as for prognosis of preterm labor. However, for the introduction in the clinical practice of diagnostic and prognostic EHG techniques, further insights are needed on the properties of the uterine electrical activation and its propagation through biological tissues. An important contribution for studying these phenomena in humans can be provided by mathematical modeling. A five-parameter analytical model of the EHG volume conductor and the cellular action potential (AP) is proposed here and tested on EHG signals recorded by a grid of 64... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335005 Mon, 01 Mar 2010 00:00:00 +0100 3335005 http://www.medworm.com/index.php?rid=3335004&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5306182 Hyperglycemia is a common metabolic problem in premature, low-birth-weight infants. Blood glucose homeostasis in this group is often disturbed by immaturity of endogenous regulatory systems and the stress of their condition in intensive care. A dynamic model capturing the fundamental dynamics of the glucose regulatory system provides a measure of insulin sensitivity ( $S_I$ ). Forecasting the most probable future $S_I$ can significantly enhance real-time glucose control by providing a clinically validated/proven level of confidence on the outcome of an intervention, and thus, increased safety against hypoglycemia. A 2-D kernel model of $S_I$ is fitted to 3567 h of identified, time-varying $S_I$ from retrospective clinical data of 25 neonatal patients with birth gestational age 23 to 28.9 ... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335004 Mon, 01 Mar 2010 00:00:00 +0100 3335004 http://www.medworm.com/index.php?rid=3335003&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5282632 Intensity-modulated radiotherapy (IMRT) is now becoming a powerful clinical technique to improve the therapeutic radio for cancer treatment. It has been demonstrated that selection of suitable beam angles is quite valuable for most of the treatment plans, especially for the complicated tumor cases and when limited number of beams is used. However, beam-angle optimization (BAO) remains a challenging inverse problem mainly due to the huge computation time. This paper introduced a DNA genetic algorithm (DNA-GA) to solve the BAO problem aiming to improve the optimization efficiency. A feasible mapping was constructed between the universal DNA-GA algorithm and the specified engineering problem of BAO. Specifically, a triplet code was used to represent a beam angle, and the angles of several bea... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335003 Mon, 01 Mar 2010 00:00:00 +0100 3335003 http://www.medworm.com/index.php?rid=3335002&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5419293 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335002 Mon, 01 Mar 2010 00:00:00 +0100 3335002 http://www.medworm.com/index.php?rid=3335001&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5419294 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335001 Mon, 01 Mar 2010 00:00:00 +0100 3335001 http://www.medworm.com/index.php?rid=3335000&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5419290%26arnumber%3D5419303 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3335000 Mon, 01 Mar 2010 00:00:00 +0100 3335000 http://www.medworm.com/index.php?rid=3216399&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5393902%26arnumber%3D5072274 A novel combination of iterative learning control (ILC) and model predictive control (MPC), referred to here as model predictive iterative learning control (MPILC), is proposed for glycemic control in type 1 diabetes mellitus. MPILC exploits two key factors: frequent glucose readings made possible by continuous glucose monitoring technology; and the repetitive nature of glucose-meal-insulin dynamics with a 24-h cycle. The proposed algorithm can learn from an individual's lifestyle, allowing the control performance to be improved from day to day. After less than 10 days, the blood glucose concentrations can be kept within a range of 90–170 mg/dL. Generally, control performance under MPILC is better than that under MPC. The proposed methodology is robust to random variations in... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3216399 Thu, 28 Jan 2010 17:19:55 +0100 3216399 http://www.medworm.com/index.php?rid=3185136&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5393902%26arnumber%3D5204189 Through an investigation of various clinical cases, heart sounds are found to be quasi-cyclostationary. Nonlinear time scaling from cycle-to-cycle is proposed to enhance cyclic stationarity, where nonlinear time scaling is approximated by a piecewise linear function. The techniques of cyclostationary signal processing are employed in this paper to reduce noise and disturbance in the cycle-frequency domain. Heart sounds can be theoretically recovered in the presence of additive, zero mean noise, and disturbance (perhaps non-Gaussian, nonstationary, or colored). The experimental tests in various conditions confirm the theoretical results. (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3185136 Tue, 19 Jan 2010 16:48:45 +0100 3185136 http://www.medworm.com/index.php?rid=3185135&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5393902%26arnumber%3D5204184 We present a new approach for automatic detection of alternating signals in large noisy spatiotemporal datasets by exploiting quantitative measures of alternans evolution, e.g., temporal persistence, and by preserving phase information. The technique specifically targets low amplitude, relatively short alternating sequences and is validated by combinatorics-derived probabilities and empirical datasets with white noise. Using high-resolution optical mapping in live cardiomyocyte networks, exhibiting calcium alternans, we reveal for the first time early fine-scale alternans, close to the noise level, which are linked to the later formation of larger regions and evolution of spatially discordant alternans. This robust method aims at quantification and better understanding of the onset of card... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3185135 Tue, 19 Jan 2010 16:48:45 +0100 3185135 http://www.medworm.com/index.php?rid=3185134&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5393902%26arnumber%3D5075606 Personalized noninvasive imaging of subject-specific cardiac electrical activity can guide and improve preventive diagnosis and treatment of cardiac arrhythmia. Compared to body surface potential (BSP) recordings and electrophysiological information reconstructed on heart surfaces, volumetric myocardial transmembrane potential (TMP) dynamics is of greater clinical importance in exhibiting arrhythmic details and arrythmogenic substrates inside the myocardium. This paper presents a physiological-model-constrained statistical framework to reconstruct volumetric TMP dynamics inside the 3-D myocardium from noninvasive BSP recordings. General knowledge of volumetric TMP activity is incorporated through the modeling of cardiac electrophysiological system, and is used to constrain TMP reconstructi... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3185134 Tue, 19 Jan 2010 16:48:45 +0100 3185134 http://www.medworm.com/index.php?rid=3185133&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5393902%26arnumber%3D5272370 The concept of kinematic synergies is proposed to address the dimensionality reduction problem in control and coordination of the human hand. This paper develops a method for extracting kinematic synergies from joint-angular-velocity profiles of hand movements. Decomposition of a limited set of synergies from numerous movements is a complex optimization problem. This paper splits the decomposition process into two stages. The first stage is to extract synergies from rapid movement tasks using singular value decomposition (SVD). A bank of template functions is then created from shifted versions of the extracted synergies. The second stage is to find weights and onset times of the synergies based on $l_1$ -minimization, whose solutions provide sparse representations of hand movements using s... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3185133 Tue, 19 Jan 2010 16:48:45 +0100 3185133 http://www.medworm.com/index.php?rid=3185132&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5393902%26arnumber%3D5268216 This paper describes a fast and fully automatic method for liver vessel segmentation on computerized tomography scan preoperative images. The basis of this method is the introduction of a 3-D geometrical moment-based detector of cylindrical shapes within the minimum-cut/maximum-flow energy minimization framework. This method represents an original way to introduce a data term as a constraint into the widely used Boykov’s graph cuts algorithm, and hence, to automate the segmentation. The method is evaluated and compared with others on a synthetic dataset. Finally, the relevancy of our method regarding the planning of a necessarily accurate percutaneous high-intensity focused ultrasound surgical operation is demonstrated with some examples. (Source: IEEE Transactions on Biomedical Eng... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3185132 Tue, 19 Jan 2010 16:48:45 +0100 3185132 http://www.medworm.com/index.php?rid=3185131&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5393902%26arnumber%3D5247102 Upright balance is believed to be maintained through active and passive mechanisms, both of which have been shown to be impacted by aging. A compensatory balance response often observed in older adults is increased co-contraction, which is generally assumed to enhance stability by increasing joint stiffness. We investigated the effect of aging on standing balance by fitting body sway data to a previously developed postural control model that includes active and passive stiffness and damping parameters. Ten young (24 $pm$ 3 years) and seven older (75 $pm$ 5 years) adults were exposed during eyes-closed stance to perturbations consisting of lateral pseudorandom floor tilts. A least-square fit of the measured body sway data to the postural control model found significantly larger active stiff... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3185131 Tue, 19 Jan 2010 16:48:45 +0100 3185131 http://www.medworm.com/index.php?rid=3185130&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5393902%26arnumber%3D5247098 A lumped parameter model of human cardiovascular–implantable rotary blood pump (iRBP) interaction has been developed based on experimental data recorded in two healthy pigs with the iRBP in situ. The model includes descriptions of the left and right heart, direct ventricular interaction through the septum and pericardium, the systemic and pulmonary circulations, as well as the iRBP. A subset of parameters was optimized in a least squares sense to faithfully reproduce the experimental measurements (pressures, flows and pump variables). Our fitted model compares favorably with our experimental measurements at a range of pump operating points. Furthermore, we have also suggested the importance of various model features, such as the curvilinearity of the end systolic pressure–vol... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3185130 Tue, 19 Jan 2010 16:48:45 +0100 3185130 http://www.medworm.com/index.php?rid=3185129&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5393902%26arnumber%3D5223670 Fractional order modeling of biological systems has received significant interest in the research community. Since the fractal geometry is characterized by a recurrent structure, the self-similar branching arrangement of the airways makes the respiratory system an ideal candidate for the application of fractional calculus theory. To demonstrate the link between the recurrence of the respiratory tree and the appearance of a fractional-order model, we develop an anatomically consistent representation of the respiratory system. This model is capable of simulating the mechanical properties of the lungs and we compare the model output with in vivo measurements of the respiratory input impedance collected in 20 healthy subjects. This paper provides further proof of the underlying fractal geometr... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3185129 Tue, 19 Jan 2010 16:48:45 +0100 3185129 http://www.medworm.com/index.php?rid=3185128&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5393902%26arnumber%3D5204200 This paper presents a nonlinear dual-reciprocity boundary element method (DRBEM) for bioheat transfer in laser-induced thermotherapy. The nonlinearity stems from the dynamic changes of tissue thermophysical and optical properties and the blood perfusion rate during laser heating. The proposed DRBEM is coupled with a modified Monte Carlo method and the Arrhenius rate equation to investigate laser light propagation, bioheat transfer, and irreversible thermal damage in tumors. The computer code is justified by comparing the DRBEM results with the finite-difference results. The photothermal processes in interstitial laser thermotherapy with single or double laser fiber scattering applicators are chosen as the demonstrative examples. The dynamic nature, together with the unique advantages of &#... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3185128 Tue, 19 Jan 2010 16:48:45 +0100 3185128 http://www.medworm.com/index.php?rid=3185127&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5393902%26arnumber%3D5075589 Successful employment of numerical techniques for the solution of forward and inverse ECG problems requires the ability to both quantify and minimize approximation errors introduced as part of the discretization process. Our objective is to develop discretization and refinement strategies involving hybrid-shaped finite elements so as to minimize approximation errors for the ECG inverse problem. We examine both the ill-posedness of the mathematical inverse problem and the ill-conditioning of the discretized system in order to propose strategies specifically designed for the ECG inverse problem. We demonstrate that previous discretization and approximation strategies may worsen the properties of the inverse problem approximation. We then demonstrate the efficacy of our strategies on both a s... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3185127 Tue, 19 Jan 2010 16:48:45 +0100 3185127 http://www.medworm.com/index.php?rid=3185126&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5393902%26arnumber%3D5072274 A novel combination of iterative learning control (ILC) and model predictive control (MPC), referred to here as model predictive iterative learning control (MPILC), is proposed for glycemic control in type 1 diabetes mellitus. MPILC exploits two key factors: frequent glucose readings made possible by continuous glucose monitoring technology; and the repetitive nature of glucose-meal-insulin dynamics with a 24-h cycle. The proposed algorithm can learn from an individual's lifestyle, allowing the control performance to be improved from day to day. After less than 10 days, the blood glucose concentrations can be kept within a range of 90–170 mg/dL. Generally, control performance under MPILC is better than that under MPC. The proposed methodology is robust to random variations in... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3185126 Tue, 19 Jan 2010 16:48:45 +0100 3185126 http://www.medworm.com/index.php?rid=3185125&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5393902%26arnumber%3D5393906 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3185125 Tue, 19 Jan 2010 16:48:45 +0100 3185125 http://www.medworm.com/index.php?rid=3185124&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5393902%26arnumber%3D5393907 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3185124 Tue, 19 Jan 2010 16:48:44 +0100 3185124 http://www.medworm.com/index.php?rid=3185123&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5393902%26arnumber%3D5393903 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3185123 Tue, 19 Jan 2010 16:48:42 +0100 3185123 http://www.medworm.com/index.php?rid=3153198&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5374006 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153198 Fri, 01 Jan 2010 00:00:00 +0100 3153198 http://www.medworm.com/index.php?rid=3153197&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5374009 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153197 Fri, 01 Jan 2010 00:00:00 +0100 3153197 http://www.medworm.com/index.php?rid=3153196&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5374011 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153196 Fri, 01 Jan 2010 00:00:00 +0100 3153196 http://www.medworm.com/index.php?rid=3153195&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5374005 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153195 Fri, 01 Jan 2010 00:00:00 +0100 3153195 http://www.medworm.com/index.php?rid=3153194&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5204186 Low-frequency transcranial ultrasound (≪1 MHz) is being investigated for a number of brain therapies, including stroke, tumor ablation, and localized opening of the blood–brain barrier. However, lower frequencies have been associated with the production of undesired standing waves and cavitation in the brain. Presently, we examine an approach to suppress standing waves during continuous-wave (CW) transcranial application. The investigation uses a small randomization in the frequency content of the signal for suppressing standing waves. The approach is studied in an ex-vivo human skull and a plastic-walled chamber, representing idealized conditions. The approach is compared to single-frequency CW operation as well as to a swept-frequency input. Acoustic field scans demonstrate... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153194 Fri, 01 Jan 2010 00:00:00 +0100 3153194 http://www.medworm.com/index.php?rid=3153193&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5247084 The present study aims to identify a new recipe for reusable tissue mimicking phantoms that allows the optical visualization of thermal lesions produced in various applications of therapeutic ultrasound where thermal mechanisms are important. The phantom was made of polyacrylamide hydrogel containing a nonionic surface-active agent (NiSAA) as a temperature-sensitive indicator. Threshold temperature above which a thermal lesion is regarded to be formed in the phantom is controlled by selecting an NiSAA. In the present study, three NiSAAs of polyoxyethylene alkyl ether series with nominal clouding points of 66 ${^circ}$C, 70 ${^circ}$C, and 80 ${^circ}$ C were chosen. Test phantoms were prepared with polyacrylamide hydrogel, corn syrup and NiSAAs [5% (w/v)]. Key acoustic properties of... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153193 Fri, 01 Jan 2010 00:00:00 +0100 3153193 http://www.medworm.com/index.php?rid=3153192&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5282638 In this paper, a computational model for localized harmonic motion (LHM) imaging-based monitoring of high-intensity focused ultrasound surgery (FUS) is presented. The LHM technique is based on a focused, time-varying ultrasound radiation force excitation, which induces local oscillatory motions at the focal region. These vibrations are tracked, using pulse-echo imaging, and then, used to estimate the mechanical properties of the sonication region. LHM is feasible for FUS monitoring because changes in the material properties during the coagulation process affect the measured displacements. The presented model includes separate models to simulate acoustic sonication fields, sonication-induced temperature elevation and mechanical motion, and pulse-echo imaging of the induced motions. These 3-... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153192 Fri, 01 Jan 2010 00:00:00 +0100 3153192 http://www.medworm.com/index.php?rid=3153191&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5184930 It has been established that while the inherent presence of bubbles increases heat generation due to scattering and absorption, inertial cavitation is responsible for elevated heating during high-intensity focused ultrasound (HIFU) application. The contribution of bubble-induced heating can be an important factor to consider, as it can be several times greater than the expected heat deposition from absorption of energy from the primary ultrasound field. The temperature and cavitation signal near the focus were measured for 5.5-s continuous-wave 1.1-MHz HIFU sonications in tissue mimicking phantoms. The measured temperature was corrected for heating predicted from the primary ultrasound absorption to isolate the temperature rise from the bubble activity. The temperature rise induced from ca... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153191 Fri, 01 Jan 2010 00:00:00 +0100 3153191 http://www.medworm.com/index.php?rid=3153190&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5223685 Glomerular capillary hemorrhage (GCH) in rat kidney provided a model for assessing in vivo gas body efficacy in diagnostic or therapeutic applications of ultrasound. Two diagnostic ultrasound machines were utilized: one monitored the harmonic B-mode contrast enhancement of the left kidney and the other exposed the right kidney for GCH production. Definity contrast agent was infused at 1, 2, 5, or 10 $mu$L/(kg·min) and infusion durations were 30, 60, 120, or 300 s. Exposure of the right kidney was at a peak rarefactional pressure amplitude of 2.3 MPa at 1.5 MHz. The circulating dose was estimated with a simple model of agent dilution and gas body loss. For 300 s infusion at 5 $mu$L/(kg·min), the left kidney image brightness increased to a plateau with an estimated 6.4 $pm$ 1.3... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153190 Fri, 01 Jan 2010 00:00:00 +0100 3153190 http://www.medworm.com/index.php?rid=3153189&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5374015 A new system is presented for generating controlled tissue heating with a clinical ultrasound scanner, and initial in vitro and in vivo results are presented that demonstrate both transient and sustained heating in the mild-hyperthermia range of 37 ${^circ}$C–42  ${^circ}$C. The system consists of a Siemens Antares ultrasound scanner, a custom dual-frequency three-row transducer array and an external temperature feedback control system. The transducer has two outer rows that operate at 1.5 MHz for tissue heating and a center row that operates at 5 MHz for B-mode imaging to guide the therapy. We compare the field maps obtained using a hydrophone against calculations of the ultrasound beam based on monochromatic and linear assumptions. Using the finite-difference ... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153189 Fri, 01 Jan 2010 00:00:00 +0100 3153189 http://www.medworm.com/index.php?rid=3153188&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5289994 The therapeutic efficacy of neurological agents is severely limited, because large compounds do not cross the blood–brain barrier (BBB). Focused ultrasound (FUS) sonication in the presence of microbubbles has been shown to temporarily open the BBB, allowing systemically administered agents into the brain. Until now, polydispersed microbubbles (1–10 $mu$m in diameter) were used, and, therefore, the bubble sizes better suited for inducing the opening remain unknown. Here, the FUS-induced BBB opening dependence on microbubble size is investigated. Bubbles at 1–2 and 4–5 $mu$m in diameter were separately size-isolated using differential centrifugation before being systemically administered in mice (n $=$ 28). The BBB opening pressure threshold was identified by vary... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153188 Fri, 01 Jan 2010 00:00:00 +0100 3153188 http://www.medworm.com/index.php?rid=3153187&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5247101 Brain treatment through the skull with high-intensity focused ultrasound can be achieved with multichannel arrays and adaptive focusing techniques such as time reversal. This method requires a reference signal to be either emitted by a real source embedded in brain tissues or computed from a virtual source, using the acoustic properties of the skull derived from computed tomography images. This noninvasive computational method focuses with precision, but suffers from modeling and repositioning errors that reduce the accessible acoustic pressure at the focus in comparison with fully experimental time reversal using an implanted hydrophone. In this paper, this simulation-based targeting has been used experimentally as a first step for focusing through an ex vivo human skull at a single locat... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153187 Fri, 01 Jan 2010 00:00:00 +0100 3153187 http://www.medworm.com/index.php?rid=3153186&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5204192 A hemispherical-focused, ultrasound phased array was designed and fabricated using 1372 cylindrical piezoelectric transducers that utilize lateral coupling for noninvasive transcranial therapy. The cylindrical transducers allowed the electrical impedance to be reduced by at least an order of magnitude, such that effective operation could be achieved without electronic matching circuits. In addition, the transducer elements generated the maximum acoustic average surface intensity of $hbox{27 W/cm}^{2}$. The array, driven at the low (306-kHz) or high frequency (840-kHz), achieved excellent focusing through an ex vivo human skull and an adequate beam steering range for clinical brain treatments. It could electronically steer the ultrasound beam over cylindrical volumes of 100-mm in diameter a... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153186 Fri, 01 Jan 2010 00:00:00 +0100 3153186 http://www.medworm.com/index.php?rid=3153185&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5170079 Therapeutic ultrasound guided by MRI is a noninvasive treatment that potentially reduces mortality, lowers medical costs, and widens accessibility of treatments for patients. Recent developments in the design and fabrication of capacitive micromachined ultrasonic transducers (CMUTs) have made them competitive with piezoelectric transducers for use in therapeutic ultrasound applications. In this paper, we present the first designs and prototypes of an eight-element, concentric-ring, CMUT array to treat upper abdominal cancers. This array was simulated and designed to focus 30–50 mm into tissue, and ablate a 2- to 3-cm-diameter tumor within 1 h. Assuming a surface acoustic output pressure of 1 MPa peak-to-peak (8.5 W/cm$^2$) at 2.5 MHz, we simulated an array that produced a focal inte... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153185 Fri, 01 Jan 2010 00:00:00 +0100 3153185 http://www.medworm.com/index.php?rid=3153184&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5290090 In this study, a simple and robust feedback-control method that relies on rapid MR thermometry to control the HIFU exposure during heating is introduced. The binary feedback algorithm adjusts the durations of the concentric ablation circles within the target volume to reach an optimal temperature. The efficacy of the binary feedback control was evaluated by performing 90 ablations in vivo and comparing the results with simulations. Feedback control of the sonications improved the reproducibility of the induced lesion size. The standard deviation of the diameter was reduced by factors of 1.9, 7.2, 5.0, and 3.4 for 4-, 8-, 12-, and 16-mm lesions, respectively. Energy efficiency was also improved, as the binary feedback method required less energy to create the desired lesion. These results s... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153184 Fri, 01 Jan 2010 00:00:00 +0100 3153184 http://www.medworm.com/index.php?rid=3153183&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5184931 This study is motivated by the need to develop noninvasive techniques for therapeutic targeting of tumors seated in organs where the therapeutic beam is partially obstructed by the ribcage, e.g., liver and kidney. We have developed an algorithm that takes advantage of the imaging capabilities of DMUAs to identify the ribs and the intercostals within the path of the therapeutic beam to produce a specified power deposition at the target while minimizing the exposure at the rib locations. This image-based refocusing algorithm takes advantage of the inherent registration between the imaging and therapeutic coordinate systems of DMUAs in the estimation of array directivity vectors at the target and rib locations. These directivity vectors are then used in solving a constrained optimization prob... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153183 Fri, 01 Jan 2010 00:00:00 +0100 3153183 http://www.medworm.com/index.php?rid=3153182&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5061635 Unresectable liver tumors are often treated with interstitial probes that modify tissue temperature, and efficacious treatment relies on image guidance for tissue targeting and assessment. Here, we report the in vivo evaluation of an interstitial applicator with a mechanically oscillating five-element dual-mode transducer. After thoroughly characterizing the transducer, tissue response to high-intensity ultrasound was numerically calculated to select parameters for experimentation in vivo. Using perfused porcine liver, B-mode sector images were formed before and after a 120-s therapy period, and M-mode imaging monitored the therapy axis during therapy. The time-averaged transducer surface intensity was 21 or 27 W/cm$^2$. Electroacoustic conversion efficiency was maximally 72 $pm$ 3%... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153182 Fri, 01 Jan 2010 00:00:00 +0100 3153182 http://www.medworm.com/index.php?rid=3153181&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5165085 High-intensity focused ultrasound (HIFU) is a therapeutic modality that can produce coagulative necrosis in biological tissue, noninvasively. This technique requires the determination of the focus of a HIFU transducer before treatment. We investigated a method to localize the focus based on the change in radio-frequency (RF) signal at HIFU intensity levels below the threshold for tissue damage. 2-D RF data were collected during the HIFU exposure at subablative intensity levels in $bm{ex vivo}$ chicken tissue. The HIFU intensity was then increased to induce necrotic lesions in tissue, visualized as hyperecho in B-mode images, and the location of hyperecho was used to represent physical lesions, as established in our prior studies. Results showed that focal RF amplitude increased immediately... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153181 Fri, 01 Jan 2010 00:00:00 +0100 3153181 http://www.medworm.com/index.php?rid=3153180&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5204193 Ultrasound-mediated delivery (USMD) is an active research topic, as researchers develop applications for therapeutic ultrasound in addition to thermal ablation. In USMD, ultrasound is used in conjunction with microbubbles and drugs, nanoparticles, siRNA, pDNA, stem cells, etc., to facilitate their cellular delivery and uptake using pressure and temperature-mediated mechanisms to bring about a desired therapeutic effect. To investigate the potential of targeted USMD of nanoparticles, pDNA, and stem cells for cardiovascular and other applications, a general-purpose preclinical research tool, therapy imaging probe system (TIPS) was designed. It consists of a wideband annular array, a small-animal acoustic coupler, a motorized positioning system, integrated control software for ultrasound imag... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153180 Fri, 01 Jan 2010 00:00:00 +0100 3153180 http://www.medworm.com/index.php?rid=3153179&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5374013 The nine papers in this special section are devoted to the topic and applicability of therapeutic ultrasound technologies and biomedical services. (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153179 Fri, 01 Jan 2010 00:00:00 +0100 3153179 http://www.medworm.com/index.php?rid=3153178&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5170065 A novel method for mapping inertial cavitation activity during high-intensity focused ultrasound (HIFU) exposure is presented. Inertial cavitation has been previously shown to result in increased heat deposition and to be associated with broadband noise emissions that can be readily monitored using a passive receiver without interference from the main HIFU signal. In the present study, the signals received passively by each of 64 elements on a standard diagnostic array placed coaxially with the HIFU transducer are combined using time exposure acoustics to generate maps of inertially cavitating regions during HIFU exposure of an agar-based tissue-mimicking material. The technique is shown to be effective in localizing single-bubble activity, as well as contiguous and disjoint cavitating reg... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153178 Fri, 01 Jan 2010 00:00:00 +0100 3153178 http://www.medworm.com/index.php?rid=3153177&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5223673 A waveform-diversity-based approach for 3-D tumor heating is compared to spot scanning for hyperthermia applications. The waveform diversity method determines the excitation signals applied to the phased array elements and produces a beam pattern that closely matches the desired power distribution. The optimization algorithm solves the covariance matrix of the excitation signals through semidefinite programming subject to a series of quadratic cost functions and constraints on the control points. A numerical example simulates a 1444-element spherical-section phased array that delivers heat to a 3-cm-diameter spherical tumor located 12 cm from the array aperture, and the results show that waveform diversity combined with mode scanning increases the heated volume within the tumor while simul... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153177 Fri, 01 Jan 2010 00:00:00 +0100 3153177 http://www.medworm.com/index.php?rid=3153176&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5223648 Targeted vascular occlusion is desirable for clinical therapies such as in the treatment of esophageal and gastric varices and varicose veins. The feasibility of ultrasound-mediated endothelial damage for vascular occlusion was studied. A segment of a rabbit auricular vein was treated in vivo with low duty cycle, high peak rarefaction pressure (9 MPa) high-intensity focused ultrasound pulses in the presence of intravenously administered circulating microbubbles, followed by fibrinogen injection, which resulted in the formation of an acute occlusive intravascular thrombus. Further investigation and refinements of treatment protocols are necessary for producing durable vascular occlusion. (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153176 Fri, 01 Jan 2010 00:00:00 +0100 3153176 http://www.medworm.com/index.php?rid=3153175&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5374012 Investigations were carried out on the manner by which pulsed–high intensity focused ultrasound (HIFU) enhances the effectiveness of tissue plasminogen activator (tPA) in whole blood clots, in vitro. Scanning electronic microscope (SEM) of the surface of the clots showed that the exposures increased exposed fibrin, as well as the number of openings to more interior regions. These findings were supported by fluorescent antibody labeling of tPA in frozen sections of clots treated post-HIFU. Here, improved accumulation at the surface and penetration of the tPA into the clots were observed in those treated with HIFU. Fluorescence recovery after photobleaching was also performed, indicating that the diffusion coefficient increased 6.3-fold for fluorescently labeled dextrans, comparable i... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153175 Fri, 01 Jan 2010 00:00:00 +0100 3153175 http://www.medworm.com/index.php?rid=3153174&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5223707 In conclusion, ultrasound-activated BR14 microbubbles increased the endothelial layer permeability. This feature can be used for future ultrasound-guided drug delivery systems. (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153174 Fri, 01 Jan 2010 00:00:00 +0100 3153174 http://www.medworm.com/index.php?rid=3153173&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5223672 This study shows how US-mediated destruction of drug-loaded polymer contrast agent can be used to deliver encapsulated drug for potential sustained release. Penetration mechanisms of these resulting particles and their ability t- o provide a sustained release from the tumor interstia will be explored in the future. (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153173 Fri, 01 Jan 2010 00:00:00 +0100 3153173 http://www.medworm.com/index.php?rid=3153172&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5223649 The study investigates a new sonication strategy with high-intensity focused ultrasound (HIFU), aiming for improvement of the original Ablatherm procedure in the prostate cancer treatment. The currently implemented and clinically used method (defined as reference) uses a single-element transducer, operated with 60% duty cycle. To implement the novel strategy, the active surface was split into two sectors, which can be powered either sequentially (for temporal switching) or simultaneously (equivalent to a single-element transducer). Numerical simulations were used to predict the lesion shape and to determine for the novel strategy the best set of treatment parameters among the 99 explored cases. The same pattern for the focal point trajectory was executed irrespectively to the sector activa... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153172 Fri, 01 Jan 2010 00:00:00 +0100 3153172 http://www.medworm.com/index.php?rid=3153171&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5306150 We have previously introduced methods for noninvasive estimation of temperature change using diagnostic ultrasound. The basic principle was validated both in vitro and in vivo by several groups worldwide. Some limitations remain, however, that have prevented these methods from being adopted in monitoring and guidance of minimally invasive thermal therapies, e.g., RF ablation and high-intensity-focused ultrasound (HIFU). In this letter, we present first results from a real-time system for 2-D imaging of temperature change using pulse-echo ultrasound. The front end of the system is a commercially available scanner equipped with a research interface, which allows the control of imaging sequence and access to the RF data in real time. A high-frame-rate 2-D RF acquisition mode, M2D, is used to ... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153171 Fri, 01 Jan 2010 00:00:00 +0100 3153171 http://www.medworm.com/index.php?rid=3153170&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5175456 In this study, the Harmonic Motion Imaging for Focused Ultrasound (HMIFU) technique is applied to monitor changes in mechanical properties of tissues during thermal therapy in a transgenic breast cancer mouse model in vivo. An HMIFU system, composed of a 4.5-MHz focused ultrasound (FUS) and a 3.3-MHz phased-array imaging transducer, was mechanically moved to image and ablate the entire tumor. The FUS transducer was driven by an amplitude-modulated (AM) signal at 15 Hz. The acoustic intensity ( $I_{rm spta}$) was equal to $hbox{1050 W/cm}^{2}$ at the focus. A digital low-pass filter was used to filter out the spectrum of the FUS beam and its harmonics prior to displacement estimation. The resulting axial displacement was estimated using 1-D cross-correlation on the acquired RF signals. Resu... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153170 Fri, 01 Jan 2010 00:00:00 +0100 3153170 http://www.medworm.com/index.php?rid=3153169&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5374014 Discusses the main topics of discussion in the special section on therpeutic ultrasound as well as the current status and key trends in the industry. (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153169 Fri, 01 Jan 2010 00:00:00 +0100 3153169 http://www.medworm.com/index.php?rid=3153168&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5374016 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153168 Fri, 01 Jan 2010 00:00:00 +0100 3153168 http://www.medworm.com/index.php?rid=3153167&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5374017 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153167 Fri, 01 Jan 2010 00:00:00 +0100 3153167 http://www.medworm.com/index.php?rid=3153166&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5374010 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153166 Fri, 01 Jan 2010 00:00:00 +0100 3153166 http://www.medworm.com/index.php?rid=3153165&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5374008 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153165 Fri, 01 Jan 2010 00:00:00 +0100 3153165 http://www.medworm.com/index.php?rid=3153164&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5374004%26arnumber%3D5374007 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3153164 Fri, 01 Jan 2010 00:00:00 +0100 3153164 http://www.medworm.com/index.php?rid=3079129&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D5339288 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3079129 Tue, 01 Dec 2009 00:00:00 +0100 3079129 http://www.medworm.com/index.php?rid=3079128&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D5339287 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3079128 Tue, 01 Dec 2009 00:00:00 +0100 3079128 http://www.medworm.com/index.php?rid=3079127&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D5339285 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3079127 Tue, 01 Dec 2009 00:00:00 +0100 3079127 http://www.medworm.com/index.php?rid=3079126&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D5204178 Spontaneous neuronal activity plays an important role in the development of the brain. Developmental changes in the spontaneous activity pattern of neuronal networks in vitro have been extensively studied by using the microelectrode array (MEA) recording system. However, little is known about the transition of spontaneous intracellular calcium dynamics, and the relationship between calcium transients and electrical activity during development. In the present paper, we carry out simultaneous recording of spontaneous electrical activity and intracellular calcium transients of rat cortical networks cultured on MEA. In one-week cultures, periodic synchronized bursts are observed and are followed by synchronized calcium transients. In three-week cultures, synchronized calcium transients are rar... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3079126 Tue, 01 Dec 2009 00:00:00 +0100 3079126 http://www.medworm.com/index.php?rid=3079125&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D5173580 The question of how perception arises from neuronal activity in the visual cortex is of fundamental importance to many issues in cognitive neuroscience. To address this question, we adopt a unique experimental paradigm in which bistable stimuli, namely structure from motion (SFM), are employed to dissociate the visual input from perception while monitoring cortical neural activity. In this paper, we analyze the dynamic responses of the multiunit activity, simultaneously collected from multiple channels in the middle temporal visual cortex of awake behaving macaque monkeys, for decoding the bistable percepts of SFM in a response-time (RT) perceptual discrimination task. Our goal is to understand how the perceptual discriminative information of neuronal population activity evolves and accumu... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3079125 Tue, 01 Dec 2009 00:00:00 +0100 3079125 http://www.medworm.com/index.php?rid=3079124&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D5204201 In this study, the influences of the integration of an implant coil on a silicon-based IC and electrode array, thin-film Parylene-C encapsulation, and physiological medium surrounding the coil were investigated systematically and quantitatively by empirical measurements. A few embodiments of implant coils with different geometrical parameters were made with a diameter of ∼5.5 mm by winding fine wire with a diameter of approximately 50 $mu$m. The parasitic influences affecting the inductive link were empirically investigated by measuring the electrical properties of coils in different configurations and in different media. The distance of power transmission between the transmit and receive coils was measured when the receive coil was in air and immersed in phosphate buffered saline s... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3079124 Tue, 01 Dec 2009 00:00:00 +0100 3079124 http://www.medworm.com/index.php?rid=3079123&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D5204196 Hyperthermia is a powerful radiosensitizer for treatment of superficial tumors. This requires body conformal antennas with a power distribution as homogeneous as possible over the skin area. The contact flexible microstrip applicators (CFMA) operating at 434 MHz exist in several sizes, including the large size 3H and 5H. This paper investigates the behavior of the electromagnetic fields for the 3H and 5H CFMA in both flat and curved configurations, and the impact on performance parameters like the penetration depth (PD) and the effective heating depth (EHD). The underlying theory behind the electromagnetic behavior in curved situations is presented as well as numerical simulations of both flat and curved configurations. The results are compared to measurements of the electromagnetic field ... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3079123 Tue, 01 Dec 2009 00:00:00 +0100 3079123 http://www.medworm.com/index.php?rid=3079122&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D5204199 A flexible needle can be accurately steered by robotically controlling the bevel tip orientation as the needle is inserted into tissue. Friction between the long, flexible needle shaft and the tissue can cause a significant discrepancy between the orientation of the needle tip and the orientation of the base where the needle angle is controlled. Our experiments show that several common phantom tissues used in needle steering experiments impart substantial friction forces to the needle shaft, resulting in a lag of more than 45 $^{circ}$ for a 10 cm insertion depth in some phantoms; clinical studies report torques large enough to cause similar errors during needle insertions. Such angle discrepancies will result in poor performance or failure of path planners and image-guided controll... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3079122 Tue, 01 Dec 2009 00:00:00 +0100 3079122 http://www.medworm.com/index.php?rid=3079121&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D5165086 In this paper, we present a new minimally invasive biopsy microdevice adapted to proteomic mass spectrometry analysis. The concept is born from a multidisciplinary collaboration in fields of proteomics, cancer research, and microtechnology. In mixing different skills, we have developed and manufactured a miniaturized biopsy device using microtechnology techniques in order to minimize tissue damage during surgical gesture. Dedicated chemically functionalized areas were added to the device in order to increase capture yield and specificity during tissue contact. Fields of application range from cancer research to the study of neurodegenerative diseases. (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3079121 Tue, 01 Dec 2009 00:00:00 +0100 3079121 http://www.medworm.com/index.php?rid=3079120&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D4637868 In the field of small animal studies, the array coil imaging has become increasingly important. In this paper, a dedicated two-channel array coil operating at 300 MHz (7 T) for high-resolution MRI (HR-MRI) of the rat knee cartilage is presented. The average gain in signal-to-noise ratio (SNR) compared to a 15-mm multipurpose surface coil was 2.2. This SNR gain was used to improve the spatial resolution of 3-D acquisitions by decreasing the voxel size from 59$,times,$59 $,times,$156 $mu$m $^3$ to 51$,times,$51 $,times,$94 $mu$ m$^3$ without time penalty. Also, a set of two array coils was used to perform a simultaneous acquisition of both knee joints of a rat, maintaining the same scanning time without SNR or spatial resolution degradation compared to the single knee joint acquisition. This... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3079120 Tue, 01 Dec 2009 00:00:00 +0100 3079120 http://www.medworm.com/index.php?rid=3079119&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D4760276 Sign language forms a communication channel among the deaf; however, automated gesture recognition could further expand their communication with the hearers. In this work, data from five-channel surface electromyogram and 3-D accelerometer from the signer's dominant hand were analyzed using intrinsic-mode entropy (IMEn) for the automated recognition of Greek sign language (GSL) isolated signs. Discriminant analysis was used to identify the effective scales of the intrinsic-mode functions and the window length for the calculation of the IMEn that contributes to the efficient classification of the GSL signs. Experimental results from the IMEn analysis applied to GSL signs corresponding to 60-word lexicon repeated ten times by three native signers have shown more than 93% mean classification ... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3079119 Tue, 01 Dec 2009 00:00:00 +0100 3079119 http://www.medworm.com/index.php?rid=3079118&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D4547474 Defective heart valves are often replaced by implants in open-heart surgery. Both mechanical and biological implants are available. Among biological implants, xenograft ones - i.e., valves grafted from animals such as pigs, are widely used. Good implants should exhibit certain typical anatomical and functional characteristics to successfully replace the native tissue. Here, we describe a video-based system for measuring quality parameters of xenograft heart valve implants, including the area of the orifice and the fluttering of the valves' leaflets, i.e., their flaps (or cusps). Our system employs automatic methods that provide a precise and reproducible way to infer the quality of an implant. The automatic analysis of both a valve's orifice and the fluttering of its leaflets offers a more... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3079118 Tue, 01 Dec 2009 00:00:00 +0100 3079118 http://www.medworm.com/index.php?rid=3079117&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D5223652 Falls are a major risk for the elderly people living independently. Rapid detection of fall events can reduce the rate of mortality and raise the chances to survive the event and return to independent living. In the last two decades, several technological solutions for detection of falls were published, but most of them suffer from critical limitations. In this paper, we present a proof of concept to an automatic fall detection system for elderly people. The system is based on floor vibration and sound sensing, and uses signal processing and pattern recognition algorithm to discriminate between fall events and other events. The classification is based on special features like shock response spectrum and mel frequency ceptral coefficients. For the simulation of human falls, we have used a h... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3079117 Tue, 01 Dec 2009 00:00:00 +0100 3079117 http://www.medworm.com/index.php?rid=3079116&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D5204198 Localization of cortical auditory evoked potentials in cochlear implant (CI) users is confounded by the presence of a stimulus artifact produced by the implant. Linearly constrained minimum variance (LCMV) beamformers are a class of adaptive spatial filters that localize sources of interest by minimizing the contributions of other uncorrelated sources. We have developed an artifact suppression method that enables an LCMV beamformer to reconstruct cortical activity with minimal artifact interference. This is accomplished by formulating the beamformer to enforce zero-gain on sources that generate the artifact lead potential. The artifact suppression method is first applied to normal hearing subject data to verify that it does not significantly distort the measured cortical responses. The eff... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3079116 Tue, 01 Dec 2009 00:00:00 +0100 3079116 http://www.medworm.com/index.php?rid=3079115&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D5223705 This paper presents a method for obstructive sleep apnea (OSA) screening based on the electrocardiogram (ECG) recording during sleep. OSA is a common sleep disorder produced by repetitive occlusions in the upper airways and this phenomenon can usually be observed also in other peripheral systems such as the cardiovascular system. Then the extraction of ECG characteristics, such as the RR intervals and the area of the QRS complex, is useful to evaluate the sleep apnea in noninvasive way. In the presented analysis, 50 recordings coming from the apnea Physionet database were used; data were split into two sets, the training and the testing set, each of which was composed of 25 recordings. A bivariate time-varying autoregressive model (TVAM) was used to evaluate beat-by-beat power spectral den... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3079115 Tue, 01 Dec 2009 00:00:00 +0100 3079115 http://www.medworm.com/index.php?rid=3079114&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D5204194 In this paper, we proposed novel noise reduction algorithms that can be used to enhance image quality in various medical imaging modalities such as magnetic resonance and multidetector computed tomography. The noisy captured 3-D data are first transformed by discrete complex wavelet transform. Using a nonlinear function, we model the data as the sum of the clean data plus additive Gaussian or Rayleigh noise. We use a mixture of bivariate Laplacian probability density functions for the clean data in the transformed domain. The MAP and minimum mean-squared error (MMSE) estimators allow us to efficiently reduce the noise. The employed prior distribution is mixture and bivariate, and thus accurately characterizes the heavy-tail distribution of clean images and exploits the interscale propertie... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3079114 Tue, 01 Dec 2009 00:00:00 +0100 3079114 http://www.medworm.com/index.php?rid=3079113&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D5175458 Portable EEG units are key tools in epilepsy diagnosis. Current systems could be made physically smaller and longer lasting by the inclusion of online data reduction methods to reduce the power required for storage or transmission of the EEG data. This paper presents a real-time data reduction algorithm based upon the discontinuous recording of the EEG: noninteresting background sections of EEG are discarded online, with only potentially diagnostically interesting sections being saved. MATLAB simulations of the algorithm on an EEG dataset containing 982 expert marked events in 4 days of data show that 90% of events can be correctly recorded while achieving a 50% data reduction. The described algorithm is formulated to have a direct, low power, hardware implementation and similar data reduc... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3079113 Tue, 01 Dec 2009 00:00:00 +0100 3079113 http://www.medworm.com/index.php?rid=3079112&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D5204188 High-frequency (20-60 MHz) ultrasound images of preclinical tumor models are sensitive to changes in tissue microstructure that accompany tumor progression and treatment responses, but the relationships between tumor microanatomy and high-frequency ultrasound backscattering are incompletely understood. This paper introduces a 3-D microanatomical model in which tissue is treated as a population of stochastically positioned spherical cells consisting of a spherical nucleus surrounded by homogeneous cytoplasm. The model is used to represent the microstructure of both healthy mouse liver and an experimental liver metastasis that are analyzed using 4',6-diamidino-2-phenylindole- and hematoxylin and eosin-stained histology specimens digitized at 20times magnification. The spatial organization of... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3079112 Tue, 01 Dec 2009 00:00:00 +0100 3079112 http://www.medworm.com/index.php?rid=3079111&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D5208326 In this paper, we examined the added value of fuzzy nonlinear regression to identify individual pharmacokinetic parameters in the case of noisy fuzzy data and/or small sample sizes. We first described three approaches that use least squares of errors as a fitting criterion for parameter estimation by fuzzy regression. Next, we compared the estimation and prediction capability of fuzzy least squares (FLS) and ordinary least squares (OLS) regressions via a simulation experiment, so as to determine the conditions of data size and variability under which one approach could be deemed superior over the other. We considered two empirical pharmacokinetic models. Our results showed that OLS regression outperformed FLS regression when the sample size was larger and/or there existed more outliers in ... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3079111 Tue, 01 Dec 2009 00:00:00 +0100 3079111 http://www.medworm.com/index.php?rid=3079110&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D5184929 The pathophysiological interpretation of EEG signals recorded with depth electrodes [i.e., local field potentials (LFPs)] during interictal (between seizures) or ictal (during seizures) periods is fundamental in the presurgical evaluation of patients with drug-resistant epilepsy. Our objective was to explain specific shape features of interictal spikes in the hippocampus (observed in LFPs) in terms of cell- and network-related parameters of neuronal circuits that generate these events. We developed a neural network model based on ldquominimalrdquo but biologically relevant neuron models interconnected through GABAergic and glutamatergic synapses that reproduce the main physiological features of the CA1 subfield. Simulated LFPs were obtained by solving the forward problem (dipole theory) fr... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3079110 Tue, 01 Dec 2009 00:00:00 +0100 3079110 http://www.medworm.com/index.php?rid=3079109&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D5175457 It has been previously documented that the main features and sensing performance of electrograms (EGMs) recorded in implantable cardioverter defibrillators (ICDs) depend on lead configuration. Although this dependence has been ascribed to differences in lead sensitivity and spatial resolution, the quantification of these two properties on ICD has not yet been attempted. In this paper, an operative framework to study the spatial resolution of ICD transvenous leads is presented. We propose to quantify the spatial resolution of ICD transvenous leads based on a new characterization called lead resolution volume (ResV). We analyzed the sensitivity distribution and the ResV of two unipolar (tip-can and coil-can ) and two bipolar (true or tip-ring and integrated or tip-coil) ICD transvenous lead ... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3079109 Tue, 01 Dec 2009 00:00:00 +0100 3079109 http://www.medworm.com/index.php?rid=3007818&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D5170084 Electrical impedance tomography (EIT) is an imaging modality that currently shows promise for the detection and characterization of breast cancer. A very significant problem in EIT imaging is the proper modeling of the interface between the body and the electrodes. We have found empirically that it is very difficult, in a clinical setting, to assure that all electrodes make satisfactory contact with the body. In addition, we have observed a capacitive effect at the skin/electrode boundary that is spatially heterogeneous. To compensate for these problems, we have developed a hybrid nonlinear–linear reconstruction algorithm using the complete electrode model in which we first estimate electrode surface impedances, by means of a Levenberg–Marquardt iterative optimization procedu... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3007818 Thu, 19 Nov 2009 16:31:27 +0100 3007818 http://www.medworm.com/index.php?rid=3007817&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D5175478 Gastric pacing is used to modulate normal or abnormal gastric slow-wave activity for therapeutic purposes. New protocols are required that are optimized for motility outcomes and energy efficiency. A computational tissue model was developed, incorporating smooth muscle and interstitial cell of Cajal layers, to enable predictive simulations of slow-wave entrainment efficacy under different pacing frequencies. Concurrent experimental validation was performed via high-resolution entrainment mapping in a porcine model (bipolar pacing protocol: 2 mA amplitude; 400 ms pulsewidth; 17-s period; midcorpus). Entrained gastric slow-wave activity was found to be anisotropic (circular direction: 8.51 mm${cdot}$s $^{-1}$; longitudinal: 4.58 mm${cdot}$s $^{-1}$), and the simulation velocities were specif... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3007817 Thu, 19 Nov 2009 16:31:27 +0100 3007817 http://www.medworm.com/index.php?rid=3007816&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D5339289 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3007816 Thu, 19 Nov 2009 16:31:27 +0100 3007816 http://www.medworm.com/index.php?rid=3007815&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D5339290 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3007815 Thu, 19 Nov 2009 16:31:27 +0100 3007815 http://www.medworm.com/index.php?rid=3007814&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5336631%26arnumber%3D5339284 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=3007814 Thu, 19 Nov 2009 16:31:27 +0100 3007814 http://www.medworm.com/index.php?rid=2943508&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5297567%26arnumber%3D5297580 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2943508 Fri, 30 Oct 2009 16:20:55 +0100 2943508 http://www.medworm.com/index.php?rid=2943507&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5297567%26arnumber%3D5297579 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2943507 Fri, 30 Oct 2009 16:20:55 +0100 2943507 http://www.medworm.com/index.php?rid=2943506&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5297567%26arnumber%3D5297569 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2943506 Fri, 30 Oct 2009 16:20:55 +0100 2943506 http://www.medworm.com/index.php?rid=2943505&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5297567%26arnumber%3D5173578 An automatic system for segmenting and constructing volumetric representations of excised intervertebral discs from peripheral quantitative computed tomography (PQCT) imagery is presented. The system is designed to allow for automatic quantitative analysis of progressive herniation damage to the intervertebral discs under flexion/extension motions combined with a compressive load. Automatic segmentation and volumetric reconstruction of intervertebral disc from PQCT imagery is a very challenging problem due to factors such as streak artifacts and unclear material density separation between contrasted intervertebral disc and surrounding bone in the PQCT imagery, as well as the formation of multiple contrasted regions under axial scans. To address these factors, a novel multiscale level set a... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2943505 Fri, 30 Oct 2009 16:20:55 +0100 2943505 http://www.medworm.com/index.php?rid=2943504&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5297567%26arnumber%3D5165080 To detect electrocochleographic (ECochG) potentials generated by the cochlea in response to auditory stimuli, either transtympanic or tympanic/extratympanic electrodes are currently used. The first are invasive, while the second are arranged in contact or very close to the tympanic membrane (TM). To avoid the discomfort and the risks inherent to the application of such conventional electrodes, this Letter presents an alternative technique. A conducting liquid is inserted into the ear canal to act as a distributed electrical interface between the TM and an external electrode. Thus, ECochG potentials are detected without any direct contact between the solid electrode and the sensitive TM. This technique was tested on ten volunteers with single-click auditory stimuli. Results showed its effic... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2943504 Fri, 30 Oct 2009 16:20:55 +0100 2943504 http://www.medworm.com/index.php?rid=2943503&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5297567%26arnumber%3D5238541 A conceptually novel prosthesis consisting of a mechatronic hand, an electromyographic classifier, and a tactile display has been developed and evaluated by addressing problems related to controllability in prosthetics: intention extraction, perception, and feeling of ownership. Experiments have been performed, and encouraging results for a young transradial amputee are reported. (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2943503 Fri, 30 Oct 2009 16:20:55 +0100 2943503 http://www.medworm.com/index.php?rid=2943502&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5297567%26arnumber%3D5184928 This study proposes a method to select a wavelet basis for classification. It uses a strategy defined by Wickerhauser and Coifman and proposes a new additive criterion describing the contrast between classes. Its performance is compared with other approaches on simulated signals and on experimental EEG signals for brain–computer interface applications. (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2943502 Fri, 30 Oct 2009 16:20:55 +0100 2943502 http://www.medworm.com/index.php?rid=2943501&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5297567%26arnumber%3D5165082 Event-related desynchronization/synchronization patterns during right/left motor imagery (MI) are effective features for an electroencephalogram-based brain–computer interface (BCI). As MI tasks are subject-specific, selection of subject-specific discriminative frequency components play a vital role in distinguishing these patterns. This paper proposes a new discriminative filter bank (FB) common spatial pattern algorithm to extract subject-specific FB for MI classification. The proposed method enhances the classification accuracy in BCI competition III dataset IVa and competition IV dataset IIb. Compared to the performance offered by the existing FB-based method, the proposed algorithm offers error rate reductions of 17.42% and 8.9% for BCI competition datasets III an... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2943501 Fri, 30 Oct 2009 16:20:55 +0100 2943501 http://www.medworm.com/index.php?rid=2943500&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5297567%26arnumber%3D5204234 The discontinuous patterns in neonatal magnetoencephalographic (MEG) data are quantified with a novel Hilbert phase (HP) based approach. The expert neurologists’ scores were used as the gold standard. The performance of this approach was analyzed using a receiver operating characteristic (ROC) curve, and it was compared with two other approaches, namely spectral ratio (SR) and discrete wavelet transform (DWT) that have been proposed for the detection of discontinuous patterns in neonatal EEG. The area under the ROC curve (AUC) was used as a performance measure. AUCs obtained for SR, HP, and DWT were 0.87, 0.80, and 0.56, respectively. Although the performance of HP was lower than SR, it carries information about the frequency content of the signal that helps to distinguish brain pat... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2943500 Fri, 30 Oct 2009 16:20:55 +0100 2943500 http://www.medworm.com/index.php?rid=2943499&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5297567%26arnumber%3D5165079 Cross-modal sensory integration between the auditory and visual systems has long been a topic of interest in cognitive neuroscience, but spatiotemporal cortical interdependence under audiovisual stimulation is still poorly understood. In this letter, parametric spectral analysis, specifically partial directed coherence (PDC), is used to study the cortical connective causal-interdependence network under audiovisual cognitive processes within the time window of the N1 component, i.e., 96--145 ms poststimulus in the event-related potential (ERP). A total of 13 subjects (age: $22.9pm 0.8$ years; male/female = $9/4$) performed an audiovisual recognition task. Multichannel EEG signals were analyzed using an adaptive multivariate autoregressive model to identify causal influences between d... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2943499 Fri, 30 Oct 2009 16:20:55 +0100 2943499 http://www.medworm.com/index.php?rid=2943498&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5297567%26arnumber%3D4814701 Deep brain stimulation (DBS) is a widely applied clinical procedure for the alleviation of pathological neural activity, and is particularly effective in suppressing the symptoms of Parkinson's disease. The mechanisms of action of DBS remain to be fully elucidated. In this paper, we present an application to DBS of the concepts of dither injection and equivalent nonlinearity from the theory of nonlinear feedback control systems. We propose that this model provides a framework for understanding the mechanism by which an injected high-frequency signal can quench undesired oscillations in closed-loop systems of interacting neurons in the brain. (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2943498 Fri, 30 Oct 2009 16:20:55 +0100 2943498 http://www.medworm.com/index.php?rid=2943497&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5297567%26arnumber%3D5165083 Brain–machine interface (BMI) systems hold the potential to return lost functions to patients with motor disorders. To date, most efforts in BMI have concentrated on decoding neural activity from forearm areas of cortex to operate a robotic arm or perform other manipulation tasks. Efforts have neglected the locomotion functions of hindlimb/trunk cortex. However, the role of cortex in hindlimb locomotion of intact rats, which are often model systems for BMI testing, is usually considered to be small. Thus, the quality of representations of locomotion available in this area was uncertain. We designed a new rodent BMI system, and tested decoding of the kinematics of trunk and hindlimbs during locomotion using linear regression. Recordings were made from the motor cortex of the hindlimb... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2943497 Fri, 30 Oct 2009 16:20:55 +0100 2943497 http://www.medworm.com/index.php?rid=2943496&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5297567%26arnumber%3D5173579 Severe lesions of the rodent or human spinal cord lead to permanent paralysis of the legs. Here, we review novel evidences suggesting that interventions combining pharmacological and electrical stimulations of the spinal cord have a high potential to promote the recovery of locomotion following severe spinal cord injuries in humans. These strategies are based on the existence of webs of circuits and receptors embedded in the spinal motor infrastructure that each modulate specific aspects of locomotor movements. We show that chemical or electrical stimulations can engage specific elements of this spinal machinery, thus resulting in distinct patterns of locomotion in paralyzed spinal rats. In turn, simultaneous chemical stimulations of neural receptors and/or electrical stimulations of multi... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2943496 Fri, 30 Oct 2009 16:20:55 +0100 2943496 http://www.medworm.com/index.php?rid=2943495&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5297567%26arnumber%3D5238546 Important advancements have been recently achieved in the field of neural interfaces to restore lost sensory and motor functions. The aim of this letter was to develop an innovative approach to increase the selectivity and the lifetime of polyimide-based intrafascicular electrodes. The main idea was to obtain a neural interface that is able to restore a good signal quality by improving the electrical connection between the active sites and the surrounding axons. The high flexibility of polyimide-based neural interfaces allows to embed microactuators in the interface core and achieve desired microdisplacements of the active sites. Nearly equiatomic nickel–titanium alloy was selected as a microactuator because of its shape memory effect. A single TiNi thin film was obtained by dc magn... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2943495 Fri, 30 Oct 2009 16:20:55 +0100 2943495 http://www.medworm.com/index.php?rid=2943494&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5297567%26arnumber%3D5223647 This letter presents progress toward an energy efficient neural data acquisition transponder for brain–computer interfaces. The transponder utilizes a four-channel time-multiplexed analog front-end and an energy efficient short-range backscattering RF link to transmit digitized wireless data. In addition, a low-complexity autonomous and adaptive digital neural signal processor is proposed to minimize wireless bandwidth and overall power dissipation. (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2943494 Fri, 30 Oct 2009 16:20:54 +0100 2943494 http://www.medworm.com/index.php?rid=2943493&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5297567%26arnumber%3D5175477 The design of materials to promote the development and/or regeneration of neuronal tissue requires the understanding of the mechanisms by which the underlying substrate topography can modulate neuronal cell differentiation and migration. We recently demonstrated that plastic nanogratings (alternating lines of grooves and ridges of submicrometer size) can effectively change the neuronal polarity state, selecting bipolar cells with aligned neurites. Here, we address the effect of nanogratings on the migration properties of differentiating PC12 cells and correlate their behavior with the polarity state induced by the substrate. During neuronal differentiation, cell–substrate interaction is sufficient to induce directional migration along the nanogratings. Control cells contacting flat ... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2943493 Fri, 30 Oct 2009 16:20:54 +0100 2943493 http://www.medworm.com/index.php?rid=2943492&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5297567%26arnumber%3D5297596 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2943492 Fri, 30 Oct 2009 16:20:54 +0100 2943492 http://www.medworm.com/index.php?rid=2943491&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5297567%26arnumber%3D5297589 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2943491 Fri, 30 Oct 2009 16:20:54 +0100 2943491 http://www.medworm.com/index.php?rid=2943490&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5297567%26arnumber%3D5297595 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2943490 Fri, 30 Oct 2009 16:20:54 +0100 2943490 http://www.medworm.com/index.php?rid=2943489&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5297567%26arnumber%3D5297583 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2943489 Fri, 30 Oct 2009 16:20:54 +0100 2943489 http://www.medworm.com/index.php?rid=2943488&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5297567%26arnumber%3D5297584 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2943488 Fri, 30 Oct 2009 16:20:54 +0100 2943488 http://www.medworm.com/index.php?rid=2943487&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5297567%26arnumber%3D5297568 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2943487 Fri, 30 Oct 2009 16:20:54 +0100 2943487 http://www.medworm.com/index.php?rid=2920016&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5291957%26arnumber%3D5291978 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2920016 Fri, 23 Oct 2009 15:43:49 +0100 2920016 http://www.medworm.com/index.php?rid=2920015&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5291957%26arnumber%3D5291958 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2920015 Fri, 23 Oct 2009 15:43:49 +0100 2920015 http://www.medworm.com/index.php?rid=2920014&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5291957%26arnumber%3D5291975 (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2920014 Fri, 23 Oct 2009 15:43:49 +0100 2920014 http://www.medworm.com/index.php?rid=2920013&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5291957%26arnumber%3D5204191 We present a novel analysis tool for time delay estimation in electrocardiographic signal processing. This tool enhances PR interval estimation (index of the atrioventricular conduction time) by limiting the distortion effect of the T wave overlapping the P wave at high heart rates. Our approach consists of modeling the T wave, canceling its influence, and finally estimating the PR intervals during exercise and recovery with the proposed generalized Woody method. Different models of the T wave are presented and compared in a statistical summary that quantitatively justifies the improvements introduced by this study. Among the different models tested, we found that a piecewise linear function significantly reduces the T wave-induced bias in the estimation process. Combining this modeling wi... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2920013 Fri, 23 Oct 2009 15:43:49 +0100 2920013 http://www.medworm.com/index.php?rid=2920012&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5291957%26arnumber%3D5170080 Microdissection testicular sperm extraction (TESE) is an invasive surgical procedure in which sparsely located healthy larger diameter tubules carrying viable spermatazoa are identified by visual examination of the seminiferous tubules of the infertile testis under a microscope, and biopsies of regions of interest are performed. In this paper, we report on microfabricated silicon microprobes integrated with an ultrasonic horn actuator and strain gauges for microdissection probe-TESE (MP-TESE) surgery. The microprobes, with axial-force-sensitive polysilicon strain gauges, have high force sensitivity ( $-0.4$ V/N). The probes were used to detect the boundaries between seminiferous tubules, thus enabling identification of individual tubule diameters. Insertion experiments were performed on ra... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2920012 Fri, 23 Oct 2009 15:43:49 +0100 2920012 http://www.medworm.com/index.php?rid=2920011&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5291957%26arnumber%3D5061879 Light addressing is an emerging and sophisticated technique that can induce pinpoint and/or patterned neuronal activation in cultured neurons. We previously developed a light-addressable electrode using hydrogenated amorphous silicon ($a$-Si:H), which was sandwiched between a tin oxide ( $hbox{SnO}_{2}$) substrate and a passivation layer of zinc antimonate ($hbox{ZnOSb}_{2}hbox{O}_{5}$) dispersed epoxy. This research developed an experimental system that simultaneously implemented light-addressed stimulation and $hbox{Ca}^{2+}$ imaging of neuronal activities. The translucent and thin laminated structure of our electrode permitted optical accesses from two directions: $hbox{Ca}^{2+}$ imaging from above and light addressing from beneath. The submillisecond bright/dark switching property of o... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2920011 Fri, 23 Oct 2009 15:43:49 +0100 2920011 http://www.medworm.com/index.php?rid=2920010&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5291957%26arnumber%3D5175503 We present results in a principal components space; however, the algorithm may be applied in any feature space where the distribution of a neuron's spikes may be modeled as Gaussian. Applications of this signal classification method to recordings from macaque parietal cortex show that it provides significantly more consistent clustering and tracking results than traditional methods based on expectation–maximization optimization of mixture models. This consistent tracking ability is crucial for intended applications of the method. (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2920010 Fri, 23 Oct 2009 15:43:49 +0100 2920010 http://www.medworm.com/index.php?rid=2920009&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5291957%26arnumber%3D5173581 Blumlein generators are used in different applications such as radars, lasers, and also recently in various biomedical studies, where the effects of high-voltage nanosecond pulses on biological cells are evaluated. In these studies, it was demonstrated that by applying high-voltage nanosecond pulses to cells, plasma membrane and cell organelles are permeabilized. As suggested in a recent publication, the repetition rate and polarity of nanosecond high-voltage pulses could have an important effect on the electropermeabilization process, and consequently, on the observed phenomena. Therefore, we designed a new Blumlein configuration that enables a higher repetition rate of variable duration of either bipolar or unipolar high-voltage pulses. We achieved a maximal pulse repetition rate of 1.1 ... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2920009 Fri, 23 Oct 2009 15:43:49 +0100 2920009 http://www.medworm.com/index.php?rid=2920008&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5291957%26arnumber%3D5130243 A method to estimate the boundary of a tumor using an interstitial microwave probe was evaluated in numerical and phantom models. This method utilizes time-domain signal reflection from the tumor/liver interface to provide information about tumor boundary in both radial and axial directions. Using computational experiments, tumors with radial diameters up to 25 mm were estimated with less than 1 mm error. Axial diameters were estimated with at most 5 mm error. Accuracy seemed to increase with radial diameter but decreased with axial diameter. Phantom experiments confirmed the computational results. These early results indicate that the proposed method may be used to estimate tumor boundary in both radial and axial dimensions without imaging. The technique may also be applicable in other si... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2920008 Fri, 23 Oct 2009 15:43:49 +0100 2920008 http://www.medworm.com/index.php?rid=2920007&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5291957%26arnumber%3D5184927 We developed a simple, light, and cheap 3-D visualization device based on mixed reality that can be used by physicians to see preoperative radiological exams in a natural way. The system allows the user to see stereoscopic “augmented images,” which are created by mixing 3-D virtual models of anatomies obtained by processing preoperative volumetric radiological images (computed tomography or MRI) with real patient live images, grabbed by means of cameras. The interface of the system consists of a head-mounted display equipped with two high-definition cameras. Cameras are mounted in correspondence of the user's eyes and allow one to grab live images of the patient with the same point of view of the user. The system does not use any external tracker to detect movements of... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2920007 Fri, 23 Oct 2009 15:43:49 +0100 2920007 http://www.medworm.com/index.php?rid=2920006&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5291957%26arnumber%3D5204182 Independent components analysis (ICA) has previously been used to denoise EEG/magnetoencephalography (MEG) signals before performing neural source localization. Source localization is then performed using a method such as beamforming or dipole fitting. Here we show how ICA can also be used as a source localization method, negating the need for beamforming and dipole fitting. This type of approach is valid whenever an estimate of the forward (mixing) model for all putative source locations is available, which includes EEG and MEG applications. The proposed method consists of estimating the forward model using the laws of physics, estimating a second forward model using ICA, and then correlating the columns of the matrices that represent the two forward models. We show that, when synthetic d... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2920006 Fri, 23 Oct 2009 15:43:49 +0100 2920006 http://www.medworm.com/index.php?rid=2920005&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5291957%26arnumber%3D4840544 In this study, we perform a comparative study of independent component analysis (ICA) and conventional filtering (CF) for the purpose of artifact reduction from simultaneous gastric EMG and magnetogastrography (MGG). EMG/MGG data were acquired from ten anesthetized pigs by obtaining simultaneous recordings using serosal electrodes (EMG) as well as with a superconducting quantum interference device biomagnetometer (MGG). The analysis of MGG waveforms using ICA and CF indicates that ICA is superior to the CF method in its ability to extract respiration and cardiac artifacts from MGG recordings. A signal frequency analysis of ICA- and CF-processed data was also undertaken using waterfall plots, and it was determined that the two methods produce qualitatively comparable results. Through the us... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2920005 Fri, 23 Oct 2009 15:43:49 +0100 2920005 http://www.medworm.com/index.php?rid=2920004&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5291957%26arnumber%3D5175429 In conclusion, a method for exploiting both the temporal and spatial redundancy, typical of multidimensional biomedical signals, has been proposed and proved to be superior to previous coding schemes. (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2920004 Fri, 23 Oct 2009 15:43:49 +0100 2920004 http://www.medworm.com/index.php?rid=2920003&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5291957%26arnumber%3D5170066 In this paper, we investigate the use of heart rate variability (HRV) for automatic newborn seizure detection. The proposed method consists of a sequence of processing steps, namely, obtaining HRV from the ECG, extracting a discriminating HRV feature set, selecting an optimal subset from the full feature set, and, finally, classifying the HRV into seizure/nonseizure using a supervised statistical classifier. Due to the fact that HRV signals are nonstationary, a set of time–frequency features from the newborn HRV is proposed and extracted. In order to achieve efficient HRV-based automatic newborn seizure detection, a two-phase wrapper-based feature selection technique is used to select the feature subset with minimum redundancy and maximum class discriminability. Tested on ECG record... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2920003 Fri, 23 Oct 2009 15:43:48 +0100 2920003 http://www.medworm.com/index.php?rid=2920002&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5291957%26arnumber%3D5166521 The calculation and visualization of temporal and phase information in the brain, such as during cognitive processes and epileptiform activity, is an important tool in EEG-based studies of physiological brain activation. To this end, we present a technique that estimates the phase and time offsets between different channels in EEG recordings of seizure activity. The offset information is visually combined with amplitude information to emphasize the most significant signal features. The estimates of phase and time offset are derived from the S-transform, a time–frequency representation that is similar to a windowed Fourier transform, but with a wavelet-like, scalable window. The phase offsets are obtained from the differences between phase spectra of S-transforms of different traces,... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2920002 Fri, 23 Oct 2009 15:43:48 +0100 2920002 http://www.medworm.com/index.php?rid=2920001&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5291957%26arnumber%3D5175430 In conclusion, a noninvasive preoperative BVP optimization strategy based on computer simulations can be used to identify the most beneficial patient-specific electrode configuration and timing delays. (Source: IEEE Transactions on Biomedical Engineering) IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2920001 Fri, 23 Oct 2009 15:43:48 +0100 2920001 http://www.medworm.com/index.php?rid=2920000&cid=s_37223_169_f&fid=37223&url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Fisnumber%3D5291957%26arnumber%3D5170082 This study presents analyses of triple-antenna configurations and designs for microwave (MW) hepatic ablation using 3-D finite-element (FE) analyses verified by in vitro experiments. Treatment of hepatic cancer often requires removal or destruction of large volume lesions. Using multiple antennas offers a potential solution for creating ablation zones with larger dimensions, as well as varied geometrical shapes. We performed both 3-D FE analyses and in vitro experiments using three identical open-tip MW antennas simultaneously, placing them in three types of configurations—“linear array,” “triangular,” and “T-shaped” arrangements. We compared coagulation volumes created, as well as temperature distribution characteristics, from the three-ant... IEEE Transactions on Biomedical Engineering journals http://www.medworm.com/rss/comments.php?id=2920000 Fri, 23 Oct 2009 15:43:48 +0100 2920000