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Feasibility study of superharmonic imaging using chirps

Proceedings of Meetings on Acoustics 2010年第1期9卷

作者： Paul Van Neer Mikhail G. Danilouchkine Guillaume Matte Marco M. Voormolen Martin D. Verweij Nico De Jong Biomedical Engineering Erasmus Medical Center Dr. Molewaterplein 50 Rotterdam Zuid-Holland 3015 GE Netherlands Faculty of Medicine Department of Circulation and Imaging (ISB) Norwegian University of Science and Technology (NTNU) Olav Kyrres gate 9-4N Trondheim 7030 Norway Faculty Electrical Engineering Mathematics and Computer Science Delft Univ Technology Mekelweg 4 Delft Delft 2628 CD Netherlands

Superharmonic imaging (SHI) targets a combination of the 3rd to 5th harmonics. It was proven to have certain advantages in comparison with the established imaging standards in medical utrasound. SHI enhances the spatial resolution and improves the quality of echographic images, mainly by eliminating reverberation artifacts at the chest wall. However, SHI suffers from ripple artifacts, originating from the spectral gaps in between harmonics, and degrading the temporal resolution. To solve this a chirp-based SHI protocol was employed and its characteristics investigated, i.e. point spread function (PSF). The protocol was implemented for an interleaved phased array probe (44+44 elements tuned at 1.0+3.7MHz), connected to a fully programmable ultrasound system. A linear chirp (center frequency 1MHz; bandwidth 40%) was used for excitation. To obtain the PSF, the RF traces were recorded at focus along the lateral axis and convolved with the decoding signal. This was computed using KZK simulations. A PSF comparison between a superharmonic chirp and the 3rd-harmonic of a 2.5-cycle Gaussian apodized sinus burst at 1MHz showed a decrease in axial pulse length of 46% at -6dB and 32% at the -20dB level in favor of SHI. Chirp based SHI is virtually free of ripple artifacts and therefore feasible.

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Integrated model of IGF-I mediated biosynthesis in a deformed articular cartilage

Integrated model of IGF-I mediated biosynthesis in a deforme...

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作者： Zhang, Lihai Gardiner, Bruce Stuart Smith, David Wamsley Pivonka, Peter Grodzinsky, Alan Jay Department of Civil and Environmental Engineering University of Melbourne Melbourne VIC 3010 Australia Engineering Computational Biology Group School of Computer Science and Software Engineering The University of Western Australia Crawley WA 6009 Australia Faculty of Engineering Computing and Mathematics The University of Western Australia 35 Stirling Highway Crawley WA 6009 Australia Center for Biomedical Engineering Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA 02139 United States

Maintenance of articular cartilage's functional mechanical properties ultimately depends on the balance between the extracellular matrix component biosynthesis, degradation, and loss. A variety of factors are known to modulate the rate of cartilage matrix synthesis (e.g., growth factors and stress/strain environment). In the present study, we develop an integrated mathematical model that quantifies biological processes within cartilage tissue modulated by insulin-like growth factors (IGFs). Specifically, the model includes IGF transport through a deforming porous media, competitive binding to binding proteins and cell receptors, and matrix macromolecule biosynthesis - particularly glycosaminoglycans (GAGs). These newly synthesized matrix molecules are then able to modify the material properties of cartilage. The model is used to investigate the effect of synovial fluid IGF-I concentration on cartilage homeostasis. The results presented here suggest that GAG production can be rapidly "switched on" when the concentration of IGF-I reaches a certain threshold, while it is predicted that high receptor concentration leads to heterogeneous matrix production. As for the combined effect of IGF-I and mechanical loading on biosynthesis, the current model predicts that a loading regime with high strain magnitude (e.g., 10%) can achieve a synergistic effect on matrix protein production. Furthermore, dynamic loading is seen to promote spatial homogeneous GAG production. © 2009 ASCE.

关键词： Biosynthesis

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MedSiGRe: Medical Signal Grid Repository, an integration to Italica project

MedSiGRe: Medical Signal Grid Repository, an integration to ...

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6th IEEE/IFIP Latin American Network Operations and Management Symposium, LANOMS 2009

作者： Milano, Federico Eijo, Juan Francisco Garcia Gomez, Adrian De Quiros, Fernan Gonzalez Bernaldo Risk, Marcelo Department of Information Systems Engineering Buenos Aires Regional Faculty National Technological University Argentina Laboratory of Complex Systems Department of Computer Science University of Buenos Aires Argentina Department of Biomedical Informatics Italian Hospital of Buenos Aires Argentina

ISBN: (纸本)9781424445509

The Italica Project is the implementation of an Electronic Health Record system at the Italian Hospital of Buenos Aires. The present work shows the implementation of a Medical Signal Grid Repository module and its integration to the Italica Project. We also describe the architecture of that module and explain the design decisions taken for its construction. The integration to the preexisting system is also presented, together with the difficulties that arose from the insertion of a data grid in an environment not used to this technology. Several issues about the security and reliability of the medical data are treated as well. In this paper we also discuss the use of the grid repository as a starting point for the development of distributed processing applications. ©2009 IEEE.

关键词： Integration

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A compact, nano-power CMOS action potential detector

A compact, nano-power CMOS action potential detector

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IEEE biomedical Circuits and Systems (BIOCAS)

作者： Senad Hiseni Chutham Sawigun Wannaya Ngamkham Wouter A. Serdijn Biomedical Electronics Group Electronics Research Laboratory Faculty of Electrical Engineering Mathematics and Computer Science Delft University of Technnology Netherlands

Real time action potential (AP) detection is an important requirement for development of fully implantable neuroprosthetic devices. We present an ultra low-power CMOS analog circuit for detection of APs embedded in a noisy signal. The proposed strategy isolates APs by detecting subsequently a positive and a negative spike of each AP. An AP is detected only if the positive spike is detected within a short period of time after the negative spike was detected. The proposed circuit has been designed to be implemented in AMIS 0.35 ¿m technology (I3T80) and has been verified in Cadence using RF spectre. The final circuit operates from a 1-V supply and consumes only 1.5 nA. The detector is verified by means of simulations with synthetic neural waveforms and is able to successfully detect APs in noisy signals.

关键词： Detectors Energy consumption Neural prosthesis Frequency estimation CMOS technology Isolation technology Circuit noise Integrated circuit technology Circuit simulation Neurons

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Dynamic translinear nonlinear energy operator

Dynamic translinear nonlinear energy operator

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European Conference on Circuit Theory and Design, ECCTD

作者： Senad Hiseni Chutham Sawigun Wouter A. Serdijn Biomedical Electronics Group Electronics Research Laboratory Faculty of Electrical Engineering Mathematics and Computer Science Delft University of Technnology Netherlands

The dynamic translinear principle, in contrast to the conventional, i.e., static, translinear principle, can be used for the realization of frequency dependent transfer functions. Using the dynamic translinear principle we can realize both linear and nonlinear differential equations. This paper presents the dynamic translinear realization of the nonlinear second-order differential equation describing the nonlinear energy operator performing the real time energy detection of analog signals. The expected behavior of the designed nonlinear energy operator is demonstrated by means of simulations.

关键词： Differential equations Bipolar transistors Transfer functions Circuit simulation Low voltage MOSFETs Capacitors Circuit synthesis biomedical electronics Laboratories

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A nano-power class-AB current multiplier for energy-based action potential detector

A nano-power class-AB current multiplier for energy-based ac...

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European Conference on Circuit Theory and Design, ECCTD

作者： Chutham Sawigun Wouter A. Serdijn Biomedical Electronics Group Electronics Research Laboratory Faculty of Electrical Engineering Mathematics and Computer Science Delft University of Technnology Netherlands

An ultra low-power class-AB four-quadrant current multiplier designed to be used in an energy-based action potential detector is presented. The multiplier is considered the first topology that provides fully class-AB operation. The topology is constituted by a class-AB current amplifier and a current splitter which can handle input signals in excess of ten times the bias current. The proposed circuit operation is based on the exponential characteristic of BJTs or subthreshold MOSFETs. The multiplier is designed using the latter devices and achieves very low power consumption. From a 0.65 V supply, simulation results using 0.13 mum CMOS model parameters show that the proposed circuit consumes 12.4 nW static power while less than -30 dB THD is achieved for an input modulation index up to 10.

关键词： Detectors MOSFETs Frequency Signal processing Circuit topology Circuit simulation Working environment noise Signal design Transconductors biomedical electronics

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Detection and removal of ocular artifacts using Independent Component Analysis and wavelets

Detection and removal of ocular artifacts using Independent ...

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International IEEE/EMBS Conference on Neural engineering, CNE

作者： Hosna Ghandeharion H. Ahmadi-Noubari Department of Biomedical Engineering Faculty of Electrical Engineering Iran University of Science and Technology Tehran Iran Department of Electrical and Computer Engineering University of British Columbia Vancouver BC Canada

In this paper a novel approach for ocular artifact (OA) removal is proposed in which a combination of independent component analysis and wavelet-based noise reduction is utilized for detection and removal of OA. At the first stage, independent basis functions attributed to OA are computed using FastICA algorithm. This is followed by designing a wavelet basis function which is tuned to have sufficient similarity in its waveform to the independent basis functions of OA. We then utilize the designed wavelet for signal decomposition in a standard discrete wavelet transform where by deleting the approximation and summing up the details of signal decomposition, we arrive at a sufficiently artifact-free EEG signal. The approach excludes thresholding challenges of wavelets and works both for eye blinks and eye movements. Applying our algorithm to 420 4-s EEG epochs, the method exhibits high performance for the removal of OA artifacts. Our wavelet design method for noise reduction can be extended to the removal other types of EEG artifacts.

关键词： Independent component analysis Wavelet analysis Electroencephalography Noise reduction Discrete wavelet transforms Electrooculography Signal resolution Wavelet transforms Signal design Anesthesia

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Discrimination of endocardial electrogram disorganization using a signal regularity analysis

Discrimination of endocardial electrogram disorganization us...

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Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： D. Novak V. Kremen D. Cuesta K. Schmidt V. Chudacek L. Lhotska Department of Cybernetics Czech Technical University Prague Czech Republic Department of Computer Science Polytechnic University of Valencia Spain Faculty of Biomedical Engineering Department of Biomedical Technology Czech Technical University Prague Czech Republic

Measures from the theory of nonlinear dynamics were applied on complex fractionated atrial electrograms (CFAEs) in order to characterize their physiological dynamic behavior. The results were obtained considering 113 short term atrial electrograms (A-EGMs) which were annotated by three experts into four classes of fractionation according to A-EGMs signal regularity. The following measures were applied on A-EGM signals: general correlation dimension, approximate entropy, detrended fluctuation analysis, Lempel-Ziv Complexity, and Katz-Sevcik, variance and box counting fractal dimension. Assessment of disorganization was evaluated by a Kruskal Wallis statistical test. Except detrended fluctuation analysis and variance fractal dimension, the CFAE disorganization was found statistically significant even for low significant level alpha = 0.001. Moreover, the increasing complexity of A-EGM signals was reflected by higher values of general correlation dimension of order 1 and approximate entropy.

关键词： Signal analysis Fractionation Fractals Entropy biomedical measurements Fluctuations Analysis of variance Frequency USA Councils Testing

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Quantitative comparison of spot detection methods in live-cell fluorescence microscopy imaging

Quantitative comparison of spot detection methods in live-ce...

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IEEE International Symposium on biomedical Imaging

作者： Ihor Smal Marco Loog Wiro Niessen Erik Meijering Biomedical Imaging Group Rotterdam Departments of Medical Informatics and Radiology Erasmus MC-University Medical Center Rotterdam Netherlands Pattern Recognition Group Faculty of Electrical Engineering Mathematics and Computer Science Delft University of Technnology Netherlands

ISBN: (纸本)9781424439317

In live-cell fluorescence microscopy imaging, quantitative analysis of biological image data generally involves the detection of many subresolution objects, appearing as diffraction-limited spots. Due to acquisition limitations, the signal-to-noise ratio (SNR) can be extremely low, making automated spot detection a very challenging task. In this paper, we quantitatively evaluate the performance of the most frequently used supervised and unsupervised detection methods for this purpose. Experiments on synthetic images of three different types, for which ground truth was available, as well as on real image data sets acquired for two different biological studies, for which we obtained expert manual annotations for comparison, revealed that for very low SNRs (ap2), the supervised (machine learning) methods perform best overall, closely followed by the detectors based on the so-called h-dome transform from mathematical morphology and the multiscale variance-stabilizing transform, which do not require a learning stage. At high SNRs (>5), the difference in performance of all considered detectors becomes negligible.

关键词： Fluorescence Microscopy Object detection Detectors biomedical imaging Machine learning Image analysis Diffraction Signal to noise ratio Filtering

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Segmentation of abdominal aortic aneurysms in CT images using a radial model approach

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10th International Conference on Intelligent Data engineering and Automated Learning, IDEAL 2009

作者： MacÍa, Iván Legarreta, Jon Haitz Paloc, Céline Graña, Manuel Maiora, Josu García, Guillermo De Blas, Mariano Biomedical Applications Department Vicomtech Donostia-San Sebastián Spain Computational Intelligence Group Computer Science Faculty University of the Basque Country Donostia-SanSebastián Spain Electronics and Telecommunications Department Technical University School University of the Basque Country Donostia-San Sebastián Spain Engineering Systems and Automation Engineering Department Technical University School University of the Basque Country Donostia-San Sebastián Spain Interventional Radiology Service Donostia Hospital Donostia-SanSebastián Spain

ISBN: (纸本)3642043933

Abdominal Aortic Aneurysm (AAA) is a dangerous condition where the weakening of the aortic wall leads to its deformation and the generation of a thrombus. To prevent a possible rupture of the aortic wall, AAAs can be treated non-invasively by means of the Endovascular Aneurysm Repair technique (EVAR), which consists of placing a stent-graft inside the aorta in order to exclude the bulge from the blood circulation and usually leads to its contraction. Nevertheless, the bulge may continue to grow without any apparent leak. In order to effectively assess the changes experienced after surgery, it is necessary to segment the aneurysm, which is a very time-consuming task. Here we describe the initial results of a novel model-based approach for the semi-automatic segmentation of both the lumen and the thrombus of AAAs, using radial functions constrained by a priori knowledge and spatial coherency. © 2009 Springer Berlin Heidelberg.

关键词： Repair

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