Biomedizinische Technik/Biomedical Engineering (Biomed Eng)

Publications in this journal

• Article: Evaluation of a semi-automatic segmentation algorithm in 3D intraoperative ultrasound brain angiography.

  Claire Chalopin, Karl Krissian, Jürgen Meixensberger, Andrea Müns, Felix Arlt, Dirk Lindner
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  ABSTRACT: Abstract In this work, we adapted a semi-automatic segmentation algorithm for vascular structures to extract cerebral blood vessels in the 3D intraoperative contrast-enhanced ultrasound angiographic (3D-iUSA) data of the brain. We quantitatively evaluated the segmentation method with a physical vascular phantom. The geometrical features of the segmentation model generated by the algorithm were compared with the theoretical tube values and manual delineations provided by observers. For a silicon tube with a radius of 2 mm, the results showed that the algorithm overestimated the lumen radii values by about 1 mm, representing one voxel in the 3D-iUSA data. However, the observers were more hindered by noise and artifacts in the data, resulting in a larger overestimation of the tube lumen (twice the reference size). The first results on 3D-iUSA patient data showed that the algorithm could correctly restitute the main vascular segments with realistic geometrical features data, despite noise, artifacts and unclear blood vessel borders. A future aim of this work is to provide neurosurgeons with a visualization tool to navigate through the brain during aneurysm clipping operations.
  Biomedizinische Technik/Biomedical Engineering 05/2013;
• Article: Histological response to and immunogenicity of different material patches implanted in rabbit abdominal walls.

  Xuemei Fan, Senlin Xu, Yanzhou Wang, Shengping Li, Yu Wang, Huicheng Xu
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  ABSTRACT: Abstract The high failure rate of traditional procedures of repairing pelvic organ prolapse by using sutures pushes multiple transvaginal mesh delivery systems into the marketplace; however, these are currently without optimal clinical results. We observed the short-term histological changes and the effects of Th1/Th2 cytokines after the implantation in rabbit abdominal walls of five materials, i.e., porcine urinary bladder matrix (UBM), cross-linked UBM, polypropylene mesh, composite cross-linked UBM, and composite UBM, and explored the feasibility of their application to pelvic reconstructive surgery. Grafts were harvested at 1, 2, 4, 8, and 12 weeks after surgery and were processed for histology in order to evaluate the host inflammatory response and the degree of tissue incorporation. Additionally, graft site cytokine levels were determined by reverse transcriptase polymerase chain reaction. The results demonstrate that the two composite groups were associated with an erosion response, whereas the other groups induced a milder response than the composite groups. The Th1/Th2 cytokine mRNA expression levels of the cross-linked UBM group at each time point were similar to that of the sham group, whereas the other groups elicited a more variable expression. The cross-linked UBM showed slow degradation, mild inflammatory response, and low immunogenicity. This suggests that cross-linked UBM is a better material of choice for pelvic reconstructive surgery.
  Biomedizinische Technik/Biomedical Engineering 05/2013;
• Article: No influence of simultaneous bone-substitute application on the success of immediately loaded dental implants: a retrospective cohort study.

  Sigmar Kopp, Detlef Behrend, Günther Kundt, Peter Ottl, Bernhard Frerich, Mareike Warkentin
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  ABSTRACT: Abstract Purpose: To examine the influence of bone-substitute application during implantation on the success of immediately placed and loaded dental implants. Materials and methods: A total of 147 consecutive patients (age, 16.5-80.4 years) were provided with 696 immediately loaded implants. The mean follow-up time was 34.1 months. Of these implants, 50.4% (n=351) were immediately placed into extraction sockets. A total of 119 implants were added by simultaneous bone-substitute application (NanoBone, Artoss GmbH, Rostock Germany), whereas the other implants were placed in healed bone. Univariate and multivariate analysis was performed using IBM SPSS V.20. Results: The overall implant success rate was 96.1%. Implants with simultaneous bone replacement had a hazard ratio of 0.877 (p=0.837); 95% CI, 0.253-3.04). Factors found to be statistically significant modifiers of success on multivariate analysis (p<0.05) included type of superstructure (p<0.001), implant-abutment connection (p<0.001), membrane use (p=0.010), and jaw (p=0.026). None of the other factors investigated were significant modifiers. Conclusions: The present study demonstrates high success rates for immediately loaded implants and their superstructures independent of the simultaneous application of bone substitute. The declared aim of socket preservation, the prevention avoiding bone loss, is achieved in the immediate implant placement scenario under immediate-loading conditions.
  Biomedizinische Technik/Biomedical Engineering 04/2013;
• Article: Young scientist award papers from the workshop on bioelectric and biomagnetic signal processing 2012.

  Jens Haueisen, Tilmann Sander-Thömmes
  Biomedizinische Technik/Biomedical Engineering 04/2013; 58(2):105-7.
• Article: Online learning algorithms for principal component analysis applied on single-lead ECGs.

  Maik Pflugradt, Steffen Mann, Viktor Feller, Yirong Lu, Reinhold Orglmeister
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  ABSTRACT: Abstract This article evaluates several adaptive approaches to solve the principal component analysis (PCA) problem applied on single-lead ECGs. Recent studies have shown that the principal components can indicate morphologically or environmentally induced changes in the ECG signal and can be used to extract other vital information such as respiratory activity. Special interest is focused on the convergence behavior of the selected gradient algorithms, which is a major criterion for the usability of the gained results. As the right choice of learning rates is very data dependant and subject to movement artifacts, a new measurement system was designed, which uses acceleration data to improve the performance of the online algorithms. As the results of PCA seem very promising, we propose to apply a single-channel independent component analysis (SCICA) as a second step, which is investigated in this paper as well.
  Biomedizinische Technik/Biomedical Engineering 03/2013;
• Article: Coupling analysis of transient cardiovascular dynamics.

  Andreas Müller, Maik Riedl, Thomas Penzel, Hendrik Bonnemeier, Jürgen Kurths, Niels Wessel
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  ABSTRACT: Abstract The analysis of effects from coupling in and between systems is important in data-driven investigations as practiced in many scientific fields. It allows deeper insights into the mechanisms of interaction emerging among individual smaller systems when forming complex systems as in the human circulatory system. For systems featuring various regimes, usually only the epochs before and after a transition between different regimes are analyzed, although relevant information might be hidden within these transitions. Transient behavior of cardiovascular variables may emerge, on the one hand, from the recovery of the system after a severe disturbance or, on the other hand, from adaptive behavior throughout changes of states. It contains important information about the processes involved and the relations between state variables such as heart rate, blood pressure, and respiration. Therefore, we apply an ensemble approach to extend the method of symbolic coupling traces to time-variant coupling analysis. These new ensemble symbolic coupling traces are capable of determining coupling direction, strength, and time offset τ from transient dynamics in multivariate cardiovascular data. We use this method to analyze data recorded during an orthostatic test to reveal a transient structure that cannot be detected by classic methods.
  Biomedizinische Technik/Biomedical Engineering 03/2013;
• Article: Are there any differences in various polyaxial locking systems? A mechanical study of different locking screws in multidirectional angular stable distal radius plates.

  Isabella Mehling, Rebekka Scheifl, Dorothea Mehler, Daniela Klitscher, Hans Hely, Pol M Rommens
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  ABSTRACT: Abstract Numerous angular stable plates for the distal radius exist, and technically based comparisons of the polyaxial locking interfaces are lacking. The aim of this mechanical study was to investigate three different locking interfaces of angular stable volar plates by cantilever bending: VA-LCP Two-Column Distal Radius Plates 2.4 mm (Synthes® GmbH, Oberdorf, Switzerland), IXOS® P4 (Martin, Tuttlingen, Germany) and VariAX™ (Stryker®, Duisburg, Germany). We assessed the strength of 0°, 5°, 10° and 15° screw locking angles and tested the bending strength from 10° to 5° angles by cyclic loading until breakage. The final setup repeated the above assessments by inclusion of four locking screws. The single screw-plate interfaces of the VA-LCP showed the highest bending moment at an angle of 0° and 5°, the IXOS® P4 at an angle of 10° and 15° and the VariAX™ when changing the insertion angle from 10° into 5°. The strength of polyaxial locking interfaces and mechanism of failure proved to be different among the examined plates.
  Biomedizinische Technik/Biomedical Engineering 03/2013;
• Article: Validity of subthalamic-cortical coherency observed in patients with Parkinson's disease.

  Antje Bock, Andrea A Kühn, Lutz Trahms, Tilmann H Sander
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  ABSTRACT: Abstract Simultaneous magnetoencephalography (MEG) and local field potential (LFP) recordings in patients with Parkinson's disease (PD) undergoing deep brain stimulation (DBS) treatment is a promising tool for both clinical application and basic research. Recordings can be accomplished during the time interval between electrode insertion and its connection to the pulse generator while electrodes are being externalized. In nine PD patients, coherence (COH) between LFP and MEG signals was calculated from the data of a 5-min simultaneous MEG-LFP rest recording. For the observed COH patterns, a validation procedure is introduced based on time-shift principal component analysis (TSPCA), which was originally developed to suppress background signals from MEG. Here TSPCA is used as a regression of the MEG signal with filtered versions of the LFP signal to intentionally remove COH. The channel mean of the original COH is compared with the residual channel mean COH after TSPCA application. COH peaks are suppressed in the 15- to 30-Hz range; at lower frequencies, the results are less obvious due to the presence of an artifact caused by a weak remanent magnetization of the externalization wires. The COH suppression is statistically significant for four out of nine subjects, and validation has been achieved, as the COH suppression yields the hypothesized outcome.
  Biomedizinische Technik/Biomedical Engineering 03/2013;
• Article: QRS complex duration enhancement as ventricular late potential indicator by signal-averaged ECG using time-amplitude alignments.

  Roberto L Avitia, Marco A Reyna, Miguel E Bravo-Zanoguera, Lucio A Cetto
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  ABSTRACT: Abstract Ventricular late potentials (VLPs) are small-amplitude waves with a short duration that appear at the end part of the QRS complex, making a QRS complex duration larger. The signal-averaged electrocardiography (ECG) technique enhances VLPs and beats, assuming noise as the only random variable. However, ECG signals are not completely stationary and different elongations appear in both time and amplitude in each beat. This research proposes to use piecewise linear approximation to segment each beat and performs the alignment of the beats using the technique known as derivative dynamic time-warping to have beats better aligned and consequently enhance the presence of VLPs. We recorded high-resolution ECGs (HRECGs) from 50 subjects in supine position with no heart-stroke antecedents. VLPs were created synthetically and added to the HRECGs. Two cases were evaluated: (i) duration of the QRS complexes with VLPs without beats alignment, and (ii) duration of QRS complexes with VLPs using beats alignment in time and amplitude. Considering QRS duration as an indicative of VLP presence, results show that when using beats alignment in time and amplitude it is possible to reach a sensitivity of 0.96 and a specificity of 0.52, as opposed to 0.72 and 0.40, respectively, when using only averaging without beats alignment in time and amplitude.
  Biomedizinische Technik/Biomedical Engineering 03/2013;
• Article: Multiple circular-circular correlation coefficients for the quantification of phase synchronization processes in the brain.

  Katrin Pauen, Galina Ivanova
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  ABSTRACT: Abstract Phase synchronization is discussed as a potential mechanism for large-scale integration in the brain. Therefore, the quantification of such synchrony is a crucial topic in brain science research. Furthermore, these cerebral integration processes are likely to involve entire brain areas; therefore, the analysis of multiple couplings is of particular interest. Because phase values are circular variables, it is possible to use circular statistical methods for their examination. In particular, circular-circular correlation coefficients form a suitable measurement to estimate the extent of phase synchronization between different signals. As a multiple circular-circular correlation concept is still pending, two new multiple circular-circular correlation coefficients are presented in this article that can be used to quantify phase couplings between one dependent and an arbitrary number of predictor signals.
  Biomedizinische Technik/Biomedical Engineering 02/2013;
• Article: Identifying causal networks of neuronal sources from EEG/MEG data with the phase slope index: a simulation study.

  Arne Ewald, Forooz Shahbazi Avarvand, Guido Nolte
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  ABSTRACT: Abstract The investigation of functional neuronal synchronization has recently become a growing field of research. With high temporal resolution, electroencephalography and magnetoencephalography are well-suited measurement techniques to identify networks of interacting sources underlying the recorded data. The analysis of the data in terms of effective connectivity, nevertheless, contains intrinsic issues such as the problem of volume conduction and the non-uniqueness of the inverse solution. Here, we briefly introduce a series of existing methods assessing these problems. To determine the locations of interacting brain sources robust to volume conduction, all computations are solely based on the imaginary part of the cross-spectrum as a trustworthy source of information. Furthermore, we demonstrate the feasibility of estimating causal relationships of systems of neuronal sources with the phase slope index in realistically simulated data. Finally, advantages and drawbacks of the applied methodology are highlighted and discussed.
  Biomedizinische Technik/Biomedical Engineering 02/2013;
• Article: Assessment of visual function during brain surgery near the visual cortex by intraoperative optical imaging.

  Stephan B Sobottka, Tobias Meyer, Matthias Kirsch, Gilfe Reiss, Edmund Koch, Ute Morgenstern, Gabriele Schackert
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  ABSTRACT: Abstract Several functional brain imaging and mapping techniques have been used for the intraoperative identification and preservation of the sensory, motor, and speech areas of the brain. However, intraoperative monitoring and mapping of the visual function is less frequently performed in the clinical routine. To our knowledge, here we demonstrate for the first time that the individual visual cortex can be mapped to the brain surface using a contact-free optical camera system during brain surgery. Intraoperative optical imaging (IOI) was performed by visual stimulation of both eyes using stobe-light flashes. Images were acquired by a camera mounted to a standard surgical microscope. Activity maps could reproducibly be computed by detecting the blood volume-dependent signal changes of the exposed cortex. To the preliminary experience, the new technique seems to be suitable for mapping the visual function in any neurosurgical intervention that requires exposure of the visual cortex. However, the clinical relevance and reliability of the technique need to be confirmed in further studies.
  Biomedizinische Technik/Biomedical Engineering 02/2013;
• Article: Ectopic beats and their influence on the morphology of subsequent waves in the electrocardiogram.

  Gustavo Lenis, Tobias Baas, Olaf Dössel
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  ABSTRACT: Abstract Ventricular ectopic beats (VEBs) trigger a characteristic response of the heart called heart rate turbulence (HRT). The HRT can be used to predict sudden cardiac death in patients with a history of myocardial infarction. In this work, we present a reliable algorithm to detect and classify ectopic beats. Every electrocardiogram (ECG) is processed with innovative filtering techniques, artifact detection methods, and a robust multichannel analysis to produce accurate annotation results. For the classification task, a support vector machine was used. Furthermore, a new approach to the analysis of HRT is proposed. The HRT is interpreted as the response of a second-order system to an external perturbation. The system theoretical parameters were estimated. The influence of VEB on the morphology of subsequent T waves was also analyzed. A strong influence was detected in the study with 14 patients experiencing frequent VEB. The evolution of the morphology of the T wave with every new beat was studied, and it could be concluded that an exponential shape underlies this dynamic process and was called morphological heart rate turbulence (MHRT). Parameters were defined to quantify the MHRT. The analysis of the MHRT could help to understand the influence of an ectopic beat on the repolarization processes of the heart and more accurately stratify the risk of sudden cardiac death.
  Biomedizinische Technik/Biomedical Engineering 02/2013;
• Article: Simultaneous assessment of autonomic nervous and vascular endothelial functions in a rat model.

  Hsien-Tsai Wu, Cyuan-Cin Liu, Cheuk-Kwan Sun, An-Bang Liu, Ching-Shuen Chen, Chun-Cheng Yang, Chien-Hsing Wang
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  ABSTRACT: Abstract Despite the importance of translational medicine in cardiovascular research, rat vascular endothelial function and sympathetic activity assessment remains challenging. This study consisted of two parts: part A examined the consistency of reactive hyperemia-elicited dilatation index (DI) before (DIOriginal) and after (DIEEMD) ensemble empirical mode decomposition (EEMD) using Wistar-Kyoto (WKY) rats (n=7). Part B compared the endothelial function and heart rate variability of normal WKY rats (group 1, n=9) with those of spontaneously hypertensive rats (group 2, n=9) at two time points of development. The SD1/SD2 ratio (SSR) was obtained from Poincaré plot analysis to evaluate sympathetic activities. Using a Bland-Altman plot, part A of the study demonstrated a lower agreement of DIOriginal than that of DIEEMD. In part B, despite no significant difference in DIEEMD between the two groups at age 10 weeks, DIEEMD was higher in group 1 (2.25±0.63 vs. 1.43±0.41 for groups 1 and 2, respectively, p=0.004) at 20 weeks. Although no notable change in SSR existed in group 1 between the two time points, a significant difference existed in group 2 (p<0.001). In conclusion, using algorithms of Poincaré plot analysis and EEMD, the impact of age and hypertension on rat vascular endothelial function and heart rate variability can be reliably assessed.
  Biomedizinische Technik/Biomedical Engineering 02/2013;
• Article: Biotechnical measurement and software system for the prediction and diagnosis of osteochondrosis of the lumbar region with the use of fuzzy logic rules.

  Riad Al-Kasasbeh, Nikolay Korenevskiy, Florin Ionescu, Mahdi Alshamasin, Andrew P Smith, Abdullah Alwadie
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  ABSTRACT: Abstract We propose a biotech measurement scheme and software based on new features for the diagnosis of backbone osteochondrosis. Together with the traditional methods of diagnosis, the energy characteristics of biologically active points (acupuncture points, or APs) are used. This new software is based on mathematical models of the internal and biologically active points of meridian structures' interaction. The information from the APs is used in the solving rules based on fuzzy logic for decision-making, together with the factors of confidence of Shortliffe, the membership functions of Zadeh, and Kullback's informativeness measures. In terms of prognostic decision rules, clinical test shows that the quality of prediction using only the energy characteristics of APs is high, with high coefficient of confidence for the control sample as well. A check on control samples allows us to recommend the obtained results for use in medical practice as a part of corresponding systems of support for decision-making.
  Biomedizinische Technik/Biomedical Engineering 02/2013; 58(1):51-55.
• Article: In vitro construction of tissue-engineered bone with bone morphogenetic protein-2-transfected rabbit bone marrow mesenchymal stem cells and hydroxyapatite nanocomposite.

  Chunlei He, Cheng He, Jianwen Mo, Xiaona Fan, Guanglin Ji, Wuyang Liu, Dongbao Wu, Weimin Zhu, Daping Wang, Hui Gao
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  ABSTRACT: Abstract Objective: The aim of this study was to investigate the adenovirus-mediated human bone morphogenetic protein-2 (Ad-BMP-2) transfection of rabbit bone marrow mesenchymal stem cells (rBMSCs), which, together with hydroxyapatite nanocomposite (Nano-HA), were used to construct tissue-engineered bone in vitro. Methods: Ad-BMP-2 adenovirus vector was prepared with the Gateway technique and was transfected into rBMSCs. Sol-flocculation method was employed to prepare Nano-HA. Immunohistochemistry, reverse transcription-polymerase chain reaction, and Western blot assay were performed to detect the BMP-2 expression in transfected cells. At 48 h after transfection, transfected cells were inoculated into the Nano-HA scaffold. After 3 and 5 days, scanning electron microscopy was performed to observe adherence and growth of these cells. The cells in the scaffold were harvested after digestion, and Western blot assay was performed to detect the BMP-2. Results: After transfection, the mRNA and protein of hBMP-2 were expressed at a high level. Scanning electron microscopy indicated that these cells were evenly distributed in the scaffold, with favorable adherence. In addition, the cells collected from the scaffold had a high expression of BMP-2. Conclusions: Adenovirus-mediated hBMP-2 transfection was successfully performed in rBMSCs, and these cells inoculated into the Nano-HA scaffold had a high expression of hBMP-2 in the scaffold. Thus, this technique is feasible to construct tissue-engineered bone in vitro.
  Biomedizinische Technik/Biomedical Engineering 02/2013; 58(1):97-104.
• Article: Basic values for heart and respiratory rates during different sleep stages in healthy infants.

  Konrad Heimann, Nicole Heussen, Peter Vaeßen, Cathrin Wallmeier, Thorsten Orlikowsky, Tobias G Wenzl
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  ABSTRACT: Abstract The aim of this study was to systematically register data for respiratory and heart rates (RR and HR, respectively) during different sleep stages [active (AS, i.e., rapid eye movement) and quiet (QS, i.e., non-rapid eye movement) sleep] and age in a large number of healthy infants (277) during the first year of life to simplify polysomnography. The reference values in this age group differ significantly between the number of patients and age at time of investigation. According to strict inclusion and exclusion criteria, the measurement of polysomnography included HR (beats per minute, or bpm), RR (breaths per minute, or breaths/min), brain waves, SO2, sound, and video. Data recording and evaluation occurred via Alice 3®/3.5®(Respironics®), classification into AS and QS sleep according to maturity. For RR, the 5th-95th percentiles during AS decreased from 25.8-47.7 breaths/min (1st month) to 17.8-27.7 breaths/min (>9 months). During QS, RR ranged from 27.4-51.5 breaths/min (1st month) to 17.8-29.2 breaths/min (>9 months). HR decreased during AS from 118.3-150.6 bpm (1st month) to 100.9-126.4 bpm (>9 months). During QS, HR decreased from 116.0-149.9 bpm (1st month) to 93.7-119.8 bpm (>9 months). The mean HR and RR significantly decreased with age in both sleep stages (p<0.05). The mean HR is significantly lower during QS compared with AS (p<0.05). Our data may serve as basic values for HR and RR in different sleep stages during the first year of life.
  Biomedizinische Technik/Biomedical Engineering 01/2013;
• Article: Contourlet transform-based sharpening enhancement of retinal images and vessel extraction application.

  Anand Swaminathan, Shantha Selva Kumari Ramapackiam, Thivya Thiraviam, Jeeva Selvaraj
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  ABSTRACT: Abstract Low-contrast retinal images have to be enhanced for good visual perception to aid in retinal vessel analysis. Classical sharpening enhancement techniques such as unsharp masking (USM) improve the contrast and bring out the information along with noise. This article uses a shift-invariant anisotropic Contourlet transform (CT) to decompose the retinal image into subbands. A new nonlinear method is applied over the subbands to modify the CT coefficients, followed by inverse CT. The proposed method is compared with a nonlinear USM (NLUSM) technique and wavelet transform-based method. The objective performance is measured in terms of enhancement measure. We observed that the proposed methodology provides better result. We demonstrate that this sharpening algorithm can be used as a preprocessing step to (i) adaptive histogram equalization and (ii) retinal vessel extraction. Pratt's figure of merit was used to analyze the vessel extracted from the retinal images with their ground truth that were obtained from STARE and DRIVE databases.
  Biomedizinische Technik/Biomedical Engineering 01/2013;