Current Directions in Biomedical Engineering

Open Access Published by De Gruyter

Volume 3 Issue 2

September 2017

Issue of Current Directions in Biomedical Engineering

Contents
Journal Overview

Open Access September 7, 2017

Biosignal-guided personalized therapy

An application for cardiac risk stratification

Lukas von Stülpnagel, Bernhard Wolf, Axel Bauer

Page range: 179-181

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Abstract

Sudden cardiac death (SCD) is the leading single cause of death in the industrialized world. Current guidelines recommend a prophylactic implantation of an implantable cardioverter-defibrillator (ICD) in patients with reduced left-ventricular ejection fraction (LVEF ≤ 35%). However, most deaths after myocardial infarction (MI) occur in patients with normal or moderately reduced LVEF (>35%). There is a large body of evidence that cardiac autonomic dysfunction after MI is linked to increased susceptibility to malignant arrhythmias. Deceleration capacity of heart rate (DC) and periodic repolarization dynamics (PRD) are novel ECG-based risk markers, which capture different facets of cardiac autonomic dysfunction. Both parameters are strong and independent predictors of mortality and SCD after MI. Previous studies indicated that combined assessment of DC and PRD allows identification of a new high-risk group among post-infarction patients that is not addressed by current guidelines, thus opening new perspectives for biosignal-guided personalized therapies.

Smoke in laparoscopic videos usually appears due to the use of electrocautery when cutting or coagulating tissues. Therefore, detecting smoke can be used for event-based annotation in laparoscopic surgeries by retrieving the events associated with the electrocauterization. Furthermore, smoke detection can also be used for automatic smoke removal. However, detecting smoke in laparoscopic video is a challenge because of the changeability of smoke patterns, the moving camera and the different lighting conditions. In this paper, we present a video-based smoke detection algorithm to detect smoke of different densities such as fog, low and high density in laparoscopic videos. The proposed method depends on extracting various visual features from the laparoscopic images and providing them to support vector machine (SVM) classifier. Features are based on motion, colour and texture patterns of the smoke. We validated our algorithm using experimental evaluation on four laparoscopic cholecystectomy videos. These four videos were manually annotated by defining every frame as smoke or non-smoke frame. The algorithm was applied to the videos by using different feature combinations for classification. Experimental results show that the combination of all proposed features gives the best classification performance. The overall accuracy (i.e. correctly classified frames) is around 84%, with the sensitivity (i.e. correctly detected smoke frames) and the specificity (i.e. correctly detected non-smoke frames) are 89% and 80%, respectively.

Medical applications like vascular endoscopy can provide additional diagnostic value for future procedures [1]. For these applications an optimal compromise between image quality and fibre flexibility has to be identified. Image quality of endoscopes is normally estimated using flat test objects or charts. For the application of vascular endoscopy a tubular test set up seems to be more beneficial. We compare three fibre endoscopes with different diameters and number of integrated fibre according to image quality and flexibility. Based on the results a recommendation for possible applications in vascular endoscopy is given.

For daily CyberKnife QA a Winston-Lutz-Test (Automated-Quality-Assurance, AQA) is used to determine sub-millimeter deviations in beam delivery accuracy. This test is performed using gafchromic film, an extensive and user-dependent method requiring the use of disposables. We therefore analyzed the usability and accuracy of high-resolution detector arrays. We analyzed a liquid-filled ionization-chamber array (Octavius 1000SRS, PTW, Germany), which has a central resolution of 2.5mm. To test sufficient sensitivity, beam profiles with robot shifts of 0.1mm along the arrays' axes were measured. The detected deviation between the shifted and central profile were compared to the real robot's position. We then compared the results to the SRS-Profiler (SunNuclear, USA) with 4.0mm resolution and to the Nonius (QUART, Germany), a single-line diode detector with 2.8mm resolution. Finally, AQA variance and usability were analyzed performing a number of AQA tests over time, which required the use of specially designed fixtures for each array, and the results were compared to film. Concerning sensitivity, the 1000SRS detected the beam profile shifts with a maximum difference of 0.11mm (mean deviation = 0.03mm) compared to the actual robot shift. The Nonius and SRS-Profiler showed differences of up to 0.15mm and 0.69mm with mean deviation of 0.05mm and 0.18mm, respectively. Analyzing the variation of AQA results over time, the 1000SRS showed a comparable standard deviation to film (0.26mm vs. 0.18mm). The SRS-Profiler and the Nonius showed a standard deviation of 0.16mm and 0.24mm, respectively. The 1000SRS seems to provide equivalent accuracy and sensitivity to the gold standard film when performing daily AQA tests. Compared to other detectors in our study the sensitivity as well as the accuracy of the 1000SRS appears to be superior and more user-friendly. Furthermore, no significant modification of the standard AQA procedure is required when introducing 1000SRS for CyberKnife AQA.

Electrical Impedance Tomography (EIT) is an imaging technique used for monitoring of ventilation distribution in the lung. Small alternating currents are injected and resulting voltages are measured on the body surface with electrodes fixed around the thorax. Two-dimensional EIT (2D-EIT) is the most common technique in clinical applications but enables visualization of only one horizontal slice of the thorax. However, additional information in the cranio-caudal direction is necessary to more comprehensively assess the ventilation distribution. 3D-EIT systems address this issue, but clinically approved systems are not yet available. The aim of this study is to realize a multi-layer EIT-system with several electrode planes. An approved EIT system functions as basis for this development (PulmoVista 500, Dräger, Lübeck, Germany). Two planes were used for the technical realization of the multi-layer EIT-system. The alternation between the planes was realised using analog switches, which were controlled via a frequency generator and transfer the injected current and the measured voltages between the different electrode planes and the EIT device. The multi-layer EIT-System was applied to a phantom tank for first pilot measurements. Results on the phantom tank with non-conductive targets at different heights reveal that the system is capable of providing information in the cranio-caudal direction. The high frame rates of EIT images combined with the high switching speed of the used analog switches enable real-time acquisition of ventilation at different thoracic planes. Thus, the modified EIT device makes it possible to comprehensively monitor the redistribution of air in the lungs during a breathing cycle, not only in a single plane, but also in the cranio-caudal direction.

The pressure drop over a pathological vessel section can be used as an important diagnostic indicator. However, it cannot be measured non-invasively. Multiple approaches for pressure reconstruction based on velocity information are available. Regarding in-vivo data introducing uncertainty these approaches may not be robust and therefore validation is required. Within this study, three independent methods to calculate pressure losses from velocity fields were implemented and compared: A three dimensional and a one dimensional method based on the Pressure Poisson Equation (PPE) as well as an approach based on the work-energy equation for incompressible fluids (WERP). In order to evaluate the different approaches, phantoms from pure Computational Fluid Dynamics (CFD) simulations and in-vivo PC-MRI measurements were used. The comparison of all three methods reveals a good agreement with respect to the CFD pressure solutions for simple geometries. However, for more complex geometries all approaches lose accuracy. Hence, this study demonstrates the need for a careful selection of an appropriate pressure reconstruction algorithm.

Laser-driven acceleration of particle beams is an emerging modality under research for biomedical applications. The spatially resolved diagnostics of laser-accelerated proton bunches is crucial for their application. The RadEye detector, featuring up to 10 cm x 5 cm area of online complementary metal-oxide-semiconductor (CMOS) detector made of 48 μm pixels, is established for x-ray, proton and ion beam diagnostics. We exploit the usually undesired ‘Image lag’ phenomenon of incomplete pixel reset to generate 2D-images with a larger dynamic range than the single frame range of 12-bit. Using 532 nm laser pulses and computer simulations for single-slit diffraction, calibration factors to stack multiple readouts were successfully derived to quantitatively reconstruct spatial information about an optical beam and hence extend the dynamic range of the detector compared to a single frame. The final goal is focus quantification for a permanent magnet quadrupole system for protons and terawatt (TW-class) laser focus diagnostics.

Deformable image registration is gradually becoming the tool of choice for motion extraction during adaptive radiotherapy. Achieving a motion vector field that accurately represents the anatomical changes requires a tissue specific transformation model. Therefore, widely used spline based models most likely fail in appropriately reproducing large anatomical changes such as the arms of the patient being positioned up and down. We present the application of a tissue specific biomechanical model with the goal to mimic patient motion even in presence of large motion. Based on the planning CT, delineated bones are used to represent the rigid anatomy of the patient. We implement ball-and-socket joints between corresponding bones in order to achieve mobility of the skeleton. An inverse kinematics approach enables the propagation of motion between individual bones across their joints, leading to an articulated skeleton that can be controlled by feature points on one or more bones. The transformation of each bone initializes a chainmail based soft tissue model to also propagate the motion into the surrounding heterogeneous soft tissue. Representation of different postures like arms up and down can be achieved within less than 1 s for the skeleton and ∼10 s for the soft tissue. Especially for large anatomical changes, the kinematics approach benefits from the direct articulation at specific joints, considerably lowering the degrees of freedom for motion description. Being the input for the chainmail based soft tissue model, the transformed bones guarantee for its meaningful initialization. The proposed biomechanical skeleton model is promising to facilitate the registration of patients’ anatomy, being positioned with arms up and arms down. The results encourage further refinement of the joints and the soft tissue model.

Open Access September 7, 2017

Radiofrequency applicator concepts for simultaneous MR imaging and hyperthermia treatment of glioblastoma multiforme

A 298 MHz (7.0 Tesla) thermal magnetic resonance simulation study

Eva Oberacker, Andre Kuehne, Jacek Nadobny, Sebastian Zschaeck, Mirko Weihrauch, Helmar Waiczies, Pirus Ghadjar, Peter Wust, Thoralf Niendorf, Lukas Winter

Page range: 473-477

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Abstract

Glioblastoma multiforme is the most frequent and most aggressive malignant brain tumor with de facto no long term curation by the use of current multimodal therapeutic approaches. The efficacy of brachytherapy and enhancing interstitial hyperthermia has been demonstrated. RF heating at ultrahigh fields (B 0 =7.0T, f=298MHz) has the potential of delivering sufficiently large thermal dosage for hyperthermia of relatively large tumor areas. This work focuses on electromagnetic field (EMF) simulations and provides realistic applicator designs tailored for simultaneous RF heating and MRI. Our simulations took advantage of target volumes derived from patient data, and our preliminary results suggest that RF power can be focused to both a small tumor area and a large clinical target volume.

The ISO 80369-series replace Luer-connectors in five application areas to fight misconnections. Although the standard avoids the mechanical problem of misconnections, the design of products and packages remains arbitrary. So, packages and products with same functions but different connectors could have similar designs and hence could be mixed-up. To ascertain whether standardization is needed for marking non-distinguishable products and packages, a risk management and usability engineering process were carried out, partly. The ensuing risk analysis created nine unacceptable risks relating to non-distinguishable packages and lookalike-products. Based on this, risk control (standardization) is needed for lookalikes with the following proposed measures: colour allocation and haptic textures for products, colour allocation and symbols for packages. Furthermore, three scenarios were planned for summative evaluation. An additional consideration of the efficiency of proposed combinations of measures and products relying on measures would be helpful.

Video-based smoke detection in laparoscopic surgery has different potential applications, such as the automatic addressing of surgical events associated with the electrocauterization task and the development of automatic smoke removal. In the literature, video-based smoke detection has been studied widely for fire surveillance systems. Nevertheless, the proposed methods are insufficient for smoke detection in laparoscopic videos because they often depend on assumptions which rarely hold in laparoscopic surgery such as static camera. In this paper, ten visual features based on motion, texture and colour of smoke are proposed and evaluated for smoke detection in laparoscopic videos. These features are RGB channels, energy-based feature, texture features based on gray level co-occurrence matrix (GLCM), HSV colour space feature, features based on the detection of moving regions using optical flow and the smoke colour in HSV colour space. These features were tested on four laparoscopic cholecystectomy videos. Experimental observations show that each feature can provide valuable information in performing the smoke detection task. However, each feature has weaknesses to detect the presence of smoke in some cases. By combining all proposed features smoke with high and even low density can be identified robustly and the classification accuracy increases significantly.

The Origin Ensemble method allows image reconstruction of photon-limited emission tomography data to be performed entirely in the image domain. This offers attractive perspectives such as including scatter events for image reconstruction in Positron Emission Tomography . In this work, the probability of single Compton scatter along a line-of-response is estimated by the Single Scatter Simulation algorithm; for every event a decision is made whether this event is reconstructed along a line or an area confined by two circular arcs holding potential scatter points. First results of 2D simulations show visual agreement with the reference and locally increased contrast recovery coefficient values.

Open Access September 7, 2017

Robotic 4D ultrasound solution for real-time visualization and teleoperation

Latency and framerate of live ultrasound volume transfer in a local network

Mohammed Al-Badri, Svenja Ipsen, Sven Böttger, Floris Ernst

Page range: 559-561

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Abstract

Automation of the image acquisition process via robotic solutions offer a large leap towards resolving ultrasound’s user-dependency. This paper, as part of a larger project aimed to develop a multipurpose 4d-ultrasonic force-sensitive robot for medical applications, focuses on achieving real-time remote visualisation for 4d ultrasound image transfer. This was possible through implementing our software modification on a GE Vivid 7 Dimension workstation, which operates a matrix array probe controlled by a KUKA LBR iiwa 7 7-DOF robotic arm. With the help of robotic positioning and the matrix array probe, fast volumetric imaging of target regions was feasible. By testing ultrasound volumes, which were roughly 880 kB in size, while using gigabit Ethernet connection, a latency of ∼57 ms was achievable for volume transfer between the ultrasound station and a remote client application, which as a result allows a frame count of 17.4 fps. Our modification thus offers for the first time real-time remote visualization, recording and control of 4d ultrasound data, which can be implemented in teleoperation.

Open Access September 7, 2017

Drowsiness discrimination in an overnight driving simulation on the basis of RR and QT intervals

Christian Heinze, Constantin Hütterer, Thomas Schnupp, Gustavo Lenis, Martin Golz

Page range: 563-567

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Abstract

We examined if ECG-based features are discrimi-native towards drowsiness. Twenty-five volunteers (19–32 years) completed 7×40 minutes of monotonous overnight driving simulation, designed to induce drowsiness. ECG (512 s-1) was recorded continuously; subjective ratings of drowsiness on the Karolinska sleepiness scale (KSS) were polled every five minutes. ECG recordings were divided into 5-min segments, each associated with the mean of one self- and two observer-KSS ratings. Those mean KSS values were binarized to obtain two classes not drowsy and drowsy . The Q-, R- and T-waves in the recordings were detected; R-peak positions were manually reviewed; the Q- and T-detection method was tested against the manual annotations of Physio-net’s QT database. Power spectral densities of RR intervals (RR-PSD) and quantiles of the empirical distribution of heart-rate corrected QTc intervals were estimated. Support-vector machines and random-holdout cross-validation were used for the estimation of the classification error. Using either RR-PSD or QTc features yielded mean test errors of 79.3 ± 0.3 % and 82.7 ± 0.5 %, respectively. Merging RR and QTc features improved the accuracy to 88.3 ± 0.2 %. QTc intervals of the class drowsy were generally prolonged com-pared to not drowsy . Our findings indicate that the inclusion of QT intervals contribute to the discrimination of driver sleepiness.

Alteration of the flow characteristics in coronary vessels is correlated with coronary heart disease (CHD). In particular, wall shear stress (WSS) appears to be a hemody-namic key factor in the genesis of CHD. Since computational fluid dynamics (CFD) is a well-known method for the inves-tigation of WSS, it may be a valuable tool for the prediction of CHD. Latest imaging techniques, such as optical coher-ence tomography (OCT) in conjunction with angiography deliver precise 2D data sets of patient-specific vessel geome-try, which can be used for CFD analysis. Current CFD stud-ies utilize patient-specific geometries, but are lacking well defined physiologic inflow conditions. In this study, we present an inflow mapping method for patient-specific arterial vessels, which is capable of consider-ing the influence of bifurcations located proximal of the OCT-data set. At first, the patient-specific vessel was recon-structed. For this purpose the OCT-based vessel cross sec-tions were arranged along an angiographic based vessel pathway. Secondly, we simulated the flow field in a generic bifurcation model by means of CFD. Thereafter the flow field of a side branch was extracted and transferred (mapped) to the inlet of the patient-specific vessel. To evaluate the influence of the physiological inlet the WSS distribution of the same patient-specific vessel was calculated using an axial-symmetric inflow condition. Analy-sis of the simulation data yielded deviations of the WSS distribution in the proximal vessel segment. A bifurcation, located upstream of the relevant vessel segment strongly affects the flow in the OCT-based vessel reconstruction and has a strong influence on the results of the numerical analy-sis. Therefore, it is important to implement not only the pa-tient-specific geometry, but also an inlet boundary condition adapted to the upstream velocity distribution reflecting the actual proximal flow situation of the vessel.

The Bauschinger effect is a phenomenon metals show as a result of plastic deformation. After a primary plastic deformation the yield strength in the opposite loading direction decreases. The aim of this study is to investigate if there is a phenomenon similar to Bauschinger effect in thermoplastic polymers for stent application that would influence the mechanical properties of these biodegradable implants. Combined uniaxial tensile with subsequent compression tests as well as conventional compression tests without prior tensile loading were performed using biodegradable polymers for stent application (PLLA and a PLLA based blend). Comparing the results of compression tests with prior tensile loading to the compression-only tests a decrease in compressive strength can be observed for both of the tested materials. The conclusion of the performed experiments is that there is a phenomenon similar to Bauschinger effect not only in metallic materials but also in the examined thermoplastic polymers. The observed reduction of compressive strength as a consequence of prior tensile loading can influence the mechanical behaviour, e.g. the radial strength, of polymeric stents after sustaining a complex load history due to crimping and expansion.

The biplanar diode arrays Delta4PT and Delta4+ has been used in our hospital since the introduction of the TomoTherapy in 2013 to ensure a good agreement between the calculated and the measured dose distributions in patient-related QA with helical TomoTherapy. The aim of this presentation is to evaluate the quality of the measurement procedure with the Delta4 phantoms Delta4PT and (since January 2016) Delta4+. This includes the influence of a cross calibration with a treatment plan with low modulation. Two analyses were performed: (i) All treatment plans in a period of three months (n=86) were not only calculated and measured with Delta4PT or Delta4+ but also with an ionization chamber (Exradin A1SL) in the homogeneous “cheese phantom”. (ii) All data measured from January 2016 to April 2017 (Delta4+, n=132) were analyzed regarding median dose deviation, Gamma analysis and others. The comparison with chamber measurements shows that all measurements with Delta4 and almost all with the ionization chambers (79 of 86) yield a deviation of measured vs. planned dose in the PTV of less than 2.5%, but with a lower variation of the Delta4 measurements. However, a strong correlation between both was not observed. The separate analysis of the measurements with the newer Delta4+ (since January 2016) shows a mean dose deviation in the PTVs of only 0.14% with a standard deviation (S.D.) of 0.69%. Before every measurement a cross calibration has been performed. Without this cross calibration, the deviation would be 0.96% with an increased standard deviation of 0.93%. It is concluded that the Delta4 systems are well suited for patient-related QA for helical TomoTherapy treatment plans. The comparison with chamber measurements shows a plausible accordance between both systems whereas the variation of single measurements is quite different. With the help of a daily cross calibration the variability of the Delta4 results is further decreased and the results show higher accuracy and reliability. According to our experience, a daily cross calibration is mandatory for a reliable patient-related QA.

Open Access September 7, 2017

A multi-institutional survey evaluating patient related QA – phase II

Inclusion of Mobius3D as a secondary dose verification tool – preliminary results

Tobias Teichmann, Henning Salz, Michael Schwedas, Simon Howitz, Tilo Wiezorek

Page range: 639-642

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Abstract

In phase I of the survey a planning intercomparison of patient-related QA was performed at 12 institutions. The participating clinics created phantom based IMRT and VMAT plans which were measured utilizing the ArcCheck diode array. Mobius3D (M3D) was used in phase II. It acts as a secondary dose verification tool for patient-specific QA based on average linac beam data collected by Mobius Medical Systems. All Quasimodo linac plans will be analyzed for the continuation of the intercomparison. We aim to determine if Mobius3D is suited for use with diverse treatment techniques, if beam model customization is needed. Initially we computed first Mobius3D results by transferring all plans from phase I to our Mobius3D server. Because of some larger PTV mean dose differences we checked if output factor customization would be beneficial. We performed measurements and output factor correction to account for discrepancies in reference conditions. Compared to Mobius3D's preconfigured average beam data values, these corrected output factors differed by ±1.5% for field sizes between 7x7cm 2 and 30x30cm 2 and to −3.9% for 3x3cm 2 . Our method of correcting the output factors turns out good congruence to M3D's reference values for these medium field sizes.

Open Access September 7, 2017

Miniature CNT-based X-ray tube: assessment for use in intraoperative radiation therapy

Miniature CNT-based X-ray tube

Ali Mahmoud-Pashazadeh, Alfredo Illanes, Fredrick Johnson Joseph, Alexander van Oepen, Axel Boese, Michael Friebe

Page range: 643-646

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Abstract

Carbon nanotube (CNT) is a new technology used to generate gamma photons in X-ray tubes. CNTs, in comparison to other small X-ray sources, produce high X-ray intensities and as they are not based on a thermionic principle they considered cold electron sources with a very high conversion of electrical to photon energy. Their small size and other interesting properties could make them feasible for use in intraoperative radiation therapy applications. In this study, physical characteristics of the photon beam generated by the CNT-based X-ray source were assessed. A soft X-ray ionization chamber and a flat panel detector was used to measure dose and photon counts, respectively. The repetitively produced pulses had almost the same photon intensities with differences of less than 1% between them. For a typical selected pulse, the variation in the pulse amplitude was also insignificant, which shows a stable radiation exposure of the tube during the ON-mode. When moving from the center of the beam profile to the lateral distance of 25 mm, both intensity profile and dose profile showed a falling trend by a factor of almost 3 in the measured values. We also tested the miniature tube with our novel radiation beam shaping collimator designed for a possible application to treat larynx tumor, which showed the possibility of interventional radiation therapy using this miniature source. An endoscopic camera attached to the system can also make it possible to optically visualize the radiation exposed area. In conclusion, CNT-based X-ray source with suitable attached collimator to shape the beam of the source, seems to provide an opportunity to deliver radiation to a desired tumor area in minimally invasive image guided medical procedures mainly in the normal cavities of the body.

Open Access September 7, 2017

Comparison of treatment plans calculated by Ray Tracing and Monte Carlo algorithms for head and thorax radiotherapy with Cyberknife

Kirsten Galonske, Martin Thiele, Iris Ernst, Ralph Lehrke, Waldemar Zylka

Page range: 647-650

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Abstract

This study investigates differences between treatment plans generated by Ray Tracing (RT) and Monte Carlo (MC) calculation algorithms in homogeneous and heterogeneous body regions. Particularly, we focus on the head and on the thorax, respectively, for robotic stereotactic radiotherapy and radiosurgery with Cyberknife. Radiation plans for tumors located in the head and in the thorax region have been calculated and compared to each other in 47 cases and several tumor types. Assuming MC as the algorithm of highest accuracy it is shown that based on selected dose parameters, RT slightly underestimates the dose in homogeneous regions and overestimates in heterogeneous regions. In addition, deviations occur due to tumor size rendering large differences for small tumors. We conclude that dose prescriptions for radiotherapy treatments should differentiate between RT and MC calculation algorithm. This is especially important for small tumors in heterogeneous body regions.

The particle generation of medical implants and drug coated balloons (DCB) is evaluated by simulating the implantation process and collecting the released particle material. In addition to size and particle counts their material composition is of interest. Raman spectroscopy and micros-copy are established methods for chemical identification. For the manual analysis of the particles different filter or rather background materials are suitable because different require-ments in height and intensity of the spectra can be compen-sated by the user. The aim of this study was to find suitable background materials for automatic particle identification. Raman analysis of background and spherical polystyrene standard particles on filters and plain surfaces was performed manually to receive evaluable spectra for automation. Auto-matic analysis was done by a) single-point spectrum meas-urement using the coordinate list of all particles, and b) scan-ning a large sample area pixel by pixel measuring back-ground and particles. For automatic analysis with method a) the polycarbonate membrane provided best results. With method b) the polysty-rene spectrum of the particles could be found on both plain surfaces and the polycarbonate membrane. Influences from the background spectrum could be kept small by thoroughly defining the focal plane with a wavelength specific autofocus mode for method a) and manually for method b).

Open Access September 7, 2017

Marker for the pre-clinical development of bone substitute materials

X-ray opaque histology cages for bone substitute testing

Michael de Wild, Simon Zimmermann, Marcel Obrecht, Michel Dard

Page range: 711-715

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Abstract

Thin mechanically stable Ti-cages have been developed for the in-vivo application as X-ray and histology markers for the optimized evaluation of pre-clinical performance of bone graft materials. A metallic frame defines the region of interest during histological investigations and supports the identification of the defect site. This standardization of the procedure enhances the quality of pre-clinical experiments. Different models of thin metallic frameworks were designed and produced out of titanium by additive manufacturing (Selective Laser Melting). The productibility, the mechanical stability, the handling and suitability of several frame geometries were tested during surgery in artificial and in ex-vivo bone before a series of cages was preclinically investigated in the female Göttingen minipigs model. With our novel approach, a flexible process was established that can be adapted to the requirements of any specific animal model and bone graft testing.

Open Access September 7, 2017

Signal and energy transmission for implanted systems

Carsten Müller, Josep M. Cardona Audí, Roman Ruff, Klaus-Peter Hoffmann

Page range: 721-724

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Abstract

Aspects and approaches for the design of systems for simultaneous signal and energy transmission for medical implants are presented. The main focus is on the consideration of the mutual influence on both transmission lines. To minimize the influence of capacitive as well as inductive paths, that affect the transmission, reducing the number of components is discussed. In order to increase the degree of miniaturization and reliability, the realization of certain functionalities is based on the so-called parasitics of electrical components. An implementation example is presented.

Restoration of hearing is a demanding surgical task which requires the insertion of a cochlear implant electrode array into the inner ear while preserving the delicate basilar membrane inside the cochlea for an atraumatic insertion. Already shortly after the first clinical success with early versions of cochlear implants the desire for a controlled insertion of the electrode array arose. Such a steerable electrode should be in its shape adaptable to the individual path of the helical inner ear in order to avoid any contact between the implant and the surrounding tissue. This article provides a short overview of concepts and actuator mechanisms investigated in the past and present with the objective of developing a steerable electrode array for an individualized insertion process. Although none of these concepts has reached clinical implementation, there are promising experimental results indicating that insertion forces can be reduced up to 60% compared to straight and not steerable electrodes. Finally, related research topics are listed which require considerable further improvements until steerable electrodes will reach clinical applicability.

A multitude of different applications for magnetic nanoparticles were already investigated. Most prominent are drug delivery, imaging and several diagnostic in-vitro methods. To implement nanotechnological applications into clinics it is advantageous to cover all development stages starting from synthesis over characterization to the production of respective material under quality controlled conditions (cGMP)

In this paper, we present a method for locating and tracking players in the game of squash using Gaussian mixture model background subtraction and agglomerative contour clustering from a calibrated single camera view. Furthermore, we describe a method for player re-identification after near total occlusion, based on stored color- and region-descriptors. For camera calibration, no additional pattern is needed, as the squash court itself can serve as a 3D calibration object. In order to exclude non-rally situations from motion analysis, we further classify each video frame into game phases using a multilayer perceptron. By considering a player’s position as well as the current game phase we are able to visualize player-individual motion patterns expressed as court coverage using pseudo colored heat-maps. In total, we analyzed two matches (six games, 1:28h) of high quality commercial videos used in sports broadcasting and compute high resolution (1cm per pixel) heat-maps. 130184 manually labeled frames (game phases and player identification) show an identification correctness of 79.28±8.99% (mean±std). Game phase classification is correct in 60.87±7.62% and the heat-map visualization correctness is 72.47±7.27%.

About this journal

Objective
Current Directions in Biomedical Engineering (CDBME) is an open access journal publishing proceeding papers, often from the annual BMTE, CURAC, and TAR conferences, but also others. It is closely related to the journal Biomedical Engineering - Biomedizinische Technik (BME-BMT) that is well established and has published articles of high quality for more than 50 years. CDBME is as BME-BMT a forum for the exchange of knowledge in the fields of biomedical engineering, medical information technology and biotechnology/bioengineering for medicine and addresses engineers, natural scientists, and clinicians working in research, industry, or clinical practice.

Topics

Diagnostic Imaging
Biosignal Processing, Biomechanics, Image Processing, Modelling and Simulation
Information and Communication in Medicine, Telemedicine and e-Health
Surgery, Minimum Invasive Interventions, Endoscopy and Image Guided Therapy
Diagnostic and Therapeutic Instrumentation, Clinical Engineering
Micro- and Nanosystems in Medicine, Active Implants, Biosensors
Neuroengineering, Neural Systems, Rehabilitation and Prosthetics
Biomaterials, Cellular and Tissue Engineering, Artificial Organs
Biomedical Engineering for Audiology, Ophthalmology, Emergency and Dental Medicine

Article formats
Conference Proceedings Papers

Volume 3 Issue 2

Issue of Current Directions in Biomedical Engineering

Simultaneous acquisition of 4D ultrasound and wireless electromagnetic tracking for in-vivo accuracy validation

Abstract

Measurement of lung tissue dynamics in artificially ventilated rats with optical coherence tomography

Abstract

Measurement of the energy spectrum of secondary neutrons in a proton therapy environment

Abstract

Spatial resolution of electrical source localization depends on inter-electrode spacing and signal-to-noise ratio

Abstract

Analysis and classification of ECG-waves and rhythms using circular statistics and vector strength

Abstract

Functional and morphological imaging of the human tympanic membrane with endoscopic optical coherence tomography

Abstract

Deep convolutional neural network approach for forehead tissue thickness estimation

Abstract

Prompt gamma spectroscopy for range control with CeBr3

Abstract

Investigation of intracochlear dual actuator stimulation in a scaled test rig

Abstract

DRUGAS: implantable telemetric system for measuring the portal venous pressure: assembly aspects

Abstract

A new device for vein localization and effect of application of disinfectant spray on its efficiency

Abstract

Contactless in ovo sex determination of chicken eggs

Abstract

Bioprinting of three dimensional tumor models: a preliminary study using a low cost 3D printer

Abstract

Expansion characteristics of coronary stents in focal stenoses

Abstract

Middle ear reconstruction with a flexible prosthesis

Abstract

A new method for effective dose calculation based on the ambient dose height distribution

Abstract

Treatment planning for MLC based robotic radiosurgery for brain metastases: plan comparison with circular fields and suggestions for planning strategies

Abstract

Enhancing the smoothness of joint motion induced by functional electrical stimulation using co-activation strategies

Abstract

Intention recognition for FES in a grasp-and-release task using volitional EMG and inertial sensors

Abstract

Automatic anatomical calibration for IMU-based elbow angle measurement in disturbed magnetic fields

Abstract

Video magnification for intraoperative assessment of vascular function

Abstract

Biosignal-guided personalized therapy

An application for cardiac risk stratification

Abstract

“Medicine 4.0”

The role of electronics, information technology and microsystems in modern medicine

Abstract

Imaging in hearing using radiotracers

Abstract

Classifying smoke in laparoscopic videos using SVM

Abstract

Development of a tool-kit for the detection of healthy and injured cardiac tissue based on MR imaging

Software tool for the visualization of injured cardiac tissue

Abstract

ZebrafishMiner: an open source software for interactive evaluation of domain-specific fluorescence in zebrafish

Abstract

Optimization of diffusion imaging for multiple target regions using maximum likelihood estimation

Abstract

Improving subviral particle tracks in fluoroscopic image sequences by global motion compensation

Abstract

Clinical utility of an endorectal MRI-guided prostate probe: preliminary examinations

Abstract

Determination of EPID convolution kernels for portal imaging using carbon target bremsstrahlung

Abstract

Polarization sensitive optical coherence tomography utilizing a buffered swept source laser

Abstract

Evaluation and image quality comparison of ultra-thin fibre endoscopes for vascular endoscopy

Abstract

INNOLAB- image guided surgery and therapy lab

Run by engineers at a hospital for interdisciplinary and useful innovation with clinicians

Abstract

Towards microprocessor-based control of droplet parameters for endoscopic laryngeal adductor reflex triggering

Abstract

Electrical interventricular delay and left ventricular delay in right ventricular pacemaker pacing before upgrading to cardiac resynchronization therapy

Abstract

Removing noise in biomedical signal recordings by singular value decomposition

Abstract

Prompt gamma spectroscopy for range control with CeBr₃