bluuebunny/crossref_metadata_2025_split huggingface dataset:
Postural workloads on paramedics during patient transport
Authors: Verjans Mark , Schütt Andrea , Schleer Philipp , Struck Detlef , Radermacher Klaus 
Published: September 2018

Abstract
Paramedics perform physically demanding tasks during patient transport in daily routine and therefore suffer more often from musculoskeletal ailments, mainly low back pain, than any other profession. We hypothesise, that current transport aids do not offer sufficient support when it comes to obstacles and stairs during patient transport. Therefore we conducted an Ovako Working Posture Analysing System (OWAS) field study to capture postural workloads during patient transport and connected the results to a survey among paramedics about occurring obstacles. The results of the OWAS analysis showed strenuous working conditions during barrier-free transport with classical transport aids, like stretcher and stretcher chair, but enormous postural workloads when barriers occurred. Our survey revealed, that stairs occurred in 38 %, and at least one barrier, like narrow passages, curbs, etc., in 48.1 % of all deployments (n=405), we can quantitatively link postural workloads with occurring obstacles. In conclusion, there is a high demand for ergonomic improvements of current transport aids and a high potential of active assist devices to reduce harmful loads on paramedics.
Controlling of a ROS-based robotic system in accordance to the assist-as-needed principle in end-effector based rehabilitation systems
Authors: Becker Sebastian , Hinterlang Wiebke , Eschert Tim , Disselhorst-Klug Catherine 
Published: September 2018

Abstract
Stroke is one of the most frequent diseases among the elderly and often leads to an ongoing failure of functions in the central nervous system. Due to the plasticity of the brain affected may regain lost motor function by repetitive training. Robotic devices can be an approach to accelerate the rehabilitation process by maximizing patients’ training intensity. End-effector based robotic systems are particularly suitable for this purpose and often an advantage over exoskeletons since the proximal part of the upper limb remains under the control of the patient. Furthermore, the integration of the assistas- needed principle (AAN) into these devices enables individualized, adaptable robotic support to patients during therapy. In this study an end-effector based robotic rehabilitation device based on the Robot Operating System (ROS) framework is introduced. The system allows patients to perform 3- dimensional movements without a therapist’s assistance. With regard to the AAN, focus was based on impedance control and an additional real-time adaption of the impedance control parameters by using a feedback loop. 10 healthy subjects took part in this study to evaluate the overall concept with regard to usability and quality of the supported movement. Hence, the three most promising adaption models of AAN (without adaption, adaption according to position and time, adaption according to velocity) under three different levels of movement support (0%, 50%, 100%) were investigated by administering a self-designed questionnaire and the robot kinematics. The results showed no significant differences between the three different adaption models of AAN. However, the subjective assessment of the movements was in keeping with robot kinematics and the control approaches as well as the overall system have experienced remarkable support.
Effects of Serum Calcium Changes on the Cardiac Action Potential and the ECG in a Computational Model
Authors: Hernández Mesa María , Pilia Nicolas , Dössel Olaf , Severi Stefano , Loewe Axel 
Published: September 2018

Abstract
Patients suffering from end stage of chronic kidney disease (CKD) often undergo haemodialysis to normalize the electrolyte concentrations. Moreover, cardiovascular disease (CVD) is the main cause of death in CKD patients. To study the connection between CKD and CVD, we investigated the effects of an electrolyte variation on cardiac signals (action potential and ECG) using a computational model. In a first step, simulations with the Himeno et al. ventricular cell model were performed on cellular level with different extracellular sodium ([Na+]o), calcium ([Ca2+]o) and potassium ([K+]o) concentrations as occurs in CKD patients. [Ca2+]o and [K+]o changes caused variations in different features describing the morphology of the AP. Changes due to a [Na+]o variation were not as prominent. Simulations with [Ca2+]o variations were also carried out on ventricular ECG level and a 12-lead ECG was computed. Thus, a multiscale simulator from ion channel to ECG reproducing the calcium-dependent inactivation of ICaL was achieved. The results on cellular and ventricular level agree with results from literature. Moreover, we suggest novel features representing electrolyte changes that have not been described in literature. These results could be helpful for further studies aiming at the estimation of ionic concentrations based on ECG recordings.
New Tracer for Magnetic Particle Imaging - SPIONs encapsulated in RBCs
Authors: Steuer Ann-Kathrin , Klinger Matthias , Pries Ralph , Lüdtke-Buzug Kerstin 
Published: September 2018

Abstract
Superparamagnetic iron oxide nanoparticles, so called SPIONs, are used as tracers in medical imaging, e. g. for magnetic particle imaging (MPI) or magnetic resonance imaging (MRI). Since the half-life time of the SPIONs in the bloodstream is quite short because they are quickly absorbed by the reticuloendothelial system (RES), the particles are introduced into human red blood cells (RBCs) to increase their half-life time in the blood circulation. The hypotonic swelling procedure is used to incorporate the particles into the RBCs. Before the SPIONs are introduced into the RBCs, they are fluorescent labelled. To evaluate the result transmission electron microscopy, magnetic particle spectroscopy and fluorescence microscopy are used. Fluorescein isothiocyanate and rose Bengal were chosen as fluorescent dyes because their biocompatibility is guaranteed. The results suggest that the method hypotonic swelling can be used to successfully introduce the nanoparticles into RBCs and that the magnetic properties of the particles which are necessary for imaging are not influenced.
Cross-sectional and en-face depolarization imaging for the assessment of dental lesions
Authors: Golde Jonas , Tetschke Florian , Walther Julia , Rosenauer Tobias , Hempel Franz , Hannig Christian , Koch Edmund , Kirsten Lars 
Published: September 2018

Abstract
Dental caries is one of the most widespread diseases and the early and non-invasive detection of carious lesions remains an ongoing topic in biomedical research. In contrast, optical coherence tomography (OCT) is an emerging, non-invasive imaging technique for near-surface structures, that has already proved its capability for manifold biomedical applications and can be extended by several modalities such as polarization sensitivity. We have recently shown that polarization sensitive OCT combined with an algorithm for depolarization imaging, visualizing the degree of polarization uniformity (DOPU), is a promising tool for the detection and assessment of carious lesions. In this paper, we evaluate different visualization approaches based on both the intensity and DOPU data with cross-sectional and en-face representations and discuss limitations and the potential of the proposed method for the assessment of dental lesions on the example of a molar tooth with a brown spot.
A compact and accurate set of basis functions for model-based reconstructions
Authors: Eckel Christina , Bannasch Sebastian , Frysch Robert , Rose Georg 
Published: September 2018

Abstract
Model-based perfusion reconstruction (MBPR) by using a weighting sum of basis functions, is used to describe the dynamic contrast agent distribution by superposition of incorporated prior knowledge. It handles temporal under-sampling in measurements acquired with a slowly rotating X-ray-based imaging system, in our case a C-arm based computed tomography (CT). However, here challenging issue arises that the computing complexity increases proportional to the number of prior knowledge elements. Thus, the aim of this study is to analyze clinical data and elaborate basis functions, that maps various patients with a small orthonormal basis set (ONB). This work is based on five reconstructed clinical perfusion CT data sets. For each patient, regions of interest were manually figured out in order to enhance the content. Therefore, bones and catheters have to be removed out of the data, to prevent a falsification of the curves by them. The principal component analysis (PCA) to compress the relevant information of perfusion and create an ONB was used. In order to achieve an ONB which also optimal maps unknown patients, the cross validation method was used, i.e. the datasets of four patients were utilized for the estimation of the ONB, while the remaining patient was used for evaluation. Finally, the ONB gets evaluated by the mean-absolute-percentage-error (MAPE) of MBPR. A compact ONB with three basis functions that maps all five patients without a significant d eviation o f t he approximated curves and the original ones is obtained. Especially, regions with high blood supply can be reconstructed very accurately and a reduction of noise is qualitatively visible in the image. An optimum ONB for the MBPR requires that the curves can be modeled as exactly as possible with a few basis elements. The use of only a few elements also leads to short computing times. In this work a good approximation of the curves with three basis elements is received. This results in an improved MBPR that in turn can lead to a higher precision of stroke diagnostics and treatments by using C-Arm CT.
Combination of Color and Focus Segmentation for Medical Images with Low Depth-of-Field
Authors: Wirth Tamara , Naber Ady , Nahm Werner 
Published: September 2018

Abstract
Image segmentation plays an increasingly important role in image processing. It allows for various applications including the analysis of an image for automatic image understanding and the integration of complementary data. During vascular surgeries, the blood flow in the vessels has to be checked constantly, which could be facilitated by a segmentation of the affected vessels. The segmentation of medical images is still done manually, which depends on the surgeon’s experience and is time-consuming. As a result, there is a growing need for automatic image segmentation methods. We propose an unsupervised method to detect the regions of no interest (RONI) in intraoperative images with low depth-of-field (DOF). The proposed method is divided into three steps. First, a color segmentation using a clustering algorithm is performed. In a second step, we assume that the regions of interest (ROI) are in focus whereas the RONI are unfocused. This allows us to segment the image using an edge-based focus measure. Finally, we combine the focused edges with the color RONI to determine the final segmentation result. When tested on different intraoperative images of aneurysm clipping surgeries, the algorithm is able to segment most of the RONI not belonging to the pulsating vessel of interest. Surgical instruments like the metallic clips can also be excluded. Although the image data for the validation of the proposed method is limited to one intraoperative video, a proof of concept is demonstrated.
Surgical Tool Classification in Laparoscopic Videos Using Convolutional Neural Network
Authors: Abdulbaki Alshirbaji Tamer , Jalal Nour Aldeen , Möller Knut 
Published: September 2018

Abstract
Laparoscopic videos are a very important source of information which is inherently available in minimally invasive surgeries. Detecting surgical tools based on that videos have gained increasing interest due to its importance in developing a context-aware system. Such system can provide guidance assistance to the surgical team and optimise the processes inside the operating room. Convolutional neural network is a robust method to learn discriminative visual features and classify objects. As it expects a uniform distribution of data over classes, it fails to identify classes which are under-presented in the training data. In this work, loss-sensitive learning approach and resampling techniques were applied to counter the negative effects of imbalanced laparoscopic data on training the CNN model. The obtained results showed improvement in the classification performance especially for detecting surgical tools which are shortly used in the procedure.
Increasing the Robustness of the automatic IMU calibration for lower Extremity Motion Analysis
Authors: Küderle Arne , Becker Sebastian , Disselhorst-Klug Catherine 
Published: September 2018

Abstract
With the advances of IMU-based human motion tracking, joint angle tracking in an home environment has become a realistic goal. Achieving it, could enable novel applications in rehabilitation and sports medicine. However, in existing systems the process of aligning the mounted sensors with the body coordinate system is either not robust enough or to complicated for fully unsupervised usage. In this publication the performance of a promising existing algorithm is evaluated with a range of different calibration motions. Further, an extension to this implementation is proposed, aiming to improve its stability when only non-ideal calibration data is available. It could be validated that the modification of the algorithm can increase the stability and reduce the dependency of the calibration on specific calibration motions. Based on these results, we recommend the proposed extension of the algorithm as a drop-in replacement for the existing implementation.
Heart rhythm model for the simulation of electric fields in transesophageal atrial pacing and cardiac resynchronization therapy
Authors: Göküs Kerem , Heinke Matthias , Hörth Johannes 
Published: September 2018

Abstract
Electric field of biventricular (BV) pacing, left ventricular (LV) electrode position and electrical interventricular desynchronization are important parameters for successful cardiac resynchronization therapy (CRT) in patients with heart failure, sinus rhythm and reduced LV ejection fraction. The aim of the study was to evaluate electric pacing field of transesophageal left atrial (LA) pacing and BV pacing with 3D heart rhythm simulation. Bipolar right atrial (RA), right ventricular (RV), LV electrodes and multipolar hemispherical esophageal LA electrodes were modeled with CST (Computer Simulation Technology, Darmstadt). Electric pacing field were simulated with bipolar RA and RV pacing with Solid S (Biotronik) electrode, bipolar LV pacing with Attain 4194 (Medtronic) electrode and bipolar LA pacing with TO8 (Osypka) esophageal electrode. 3D heart rhythm model with esophagus allowed electric pacing field simulation of 4-chamber pacing with bipolar intracardiac RA, RV, LV pacing and bipolar transesophageal LA pacing. The pacing amplitudes were 3V RA pacing amplitude, 50V LA pacing amplitude, 1.5V RV pacing amplitude and 3V LV pacing amplitude with 0.5ms pacing pulse duration. The atrioventricular delay between RA pacing and BV pacing was 140ms atrioventricular pacing delay and simultaneous RV and LV pacing. Electric pacing fields were simulated during the different pacing modes AAI, VVI, DDD and DDD0V. The intracardiac far-field pacing potentials were evaluated with intracardiac electrodes and a distance of 1mm from the electrodes with RA electrode 1.104V, RV electrode 0.703V and LV electrode 1.32V. The transesophageal far-field pacing potential was evaluated with transesophageal electrode and a distance of 10mm from the elelctrode with LA electrode 6.076V. Heart rhythm model simulation with esophagus allows evaluation of electric pacing fields in AAI, VVI, DDD, DDD0V and DDD0D pacing modes. Electric pacing field of RA, RV and LV pacing in combination with LA pacing may additional useful pacing mode in CRT non-responders.
Testing of dynamic wrist joint external fixator mobility and reaction moment
Authors: Martin Heiner , Stiehm Michael , Rinas Ingmar , Grabow Niels , Mittlmeier Thomas 
Published: September 2018

Abstract
For the investigation of reaction moments of wrist joint with external fixator, a test device was developed that allows a well-defined investigation of the joint loads during hand flexion movements. The reaction moments are considered as a measure for the joint loads due to the constraint forces, which occur with differences of the rotation axis of the fixator device from the physiological rotation axis of the wrist joint. The developed test device allows a dynamic momentum load application into the wrist by a servohydraulic testing machine. This testing device converts the force to a moment by a constant lever arm and allows thereby the measurement of the reaction moments by the force load cell of the testing machine. Measurements on cadaveric wrist joints with external fixator can be thereby performed under reproducible conditions. The cadaveric wrist joints can be integrally casted into bone cement and thereby clamped to the testing device. Preliminary experiments with artificial bones showed that forces within the measuring range of the load cell of the testing machine can be measured. The design of the test device is presented. Hence, the requirements for measurements of the reaction moments with wrists with external fixator for distal radius fractures under dynamic loads are created.
Histological Image Processing for the Assessment of Tissue Engineered Cartilage
Authors: Munz Michael , Och Fabian , Wenzel Ulla , Hessling Martin , Hasch Katja , Goldberg-Bockhorn Eva , Rotter Nicole 
Published: September 2018

Abstract
In a recently developed perfusion bioreactor, human nasal septum chondrocytes were seeded on decellularized porcine collagen scaffolds and cultivated for 6 weeks. Afterwards, the samples were stained with alcian blue and multiple histological microscope images were taken to assess the migration of the human cells and their redifferentiation. In this paper, we propose an image processing algorithm to objectively quantify the cultivation results. This algorithm performs a white balance, detects cell nuclei and their migration depth, and detects lacunae and their orientation. To evaluate performance, sensitivity and precision are calculated using manually labeled data over 50 images. The detection of cell nuclei has a reasonable precision (73%), but the level of sensitivity (42%) should be further improved. The proposed method demonstrates acceptable level of precision (83%) and sensitivity (86%) for the detection of lacunae.
Increased baroreceptor sensitivity in a patient with hereditary spastic paraplegia – type SPG11
Authors: Fischer Gerald , Baumgartner Sigl Sara , Baumgarten Daniel , Fortin Jürgen 
Published: September 2018

Abstract
An 18 years old male patient was diagnosed with genetically confirmed hereditary spastic paraplegia of type SPG11 - a rare disease of neurodegeneration. During normal clinical routine investigation, he presented with a moderate sinus bradycardia. The function of the cardiovascular system was investigated by recording electrocardiogram, impedance cardiogram and continuous blood pressure non-invasively. Cardiac function appeared normal in all modalities. Baroreflex sensitivity was strongly increased by a factor of 2.8. Results indicate that further to hyperactivity of deep tendon reflexes, also the responsiveness regarding control of heart rhythm by baroreceptors is significantly increased. This finding provides evidence for the impact of a neurological disorder onto the cardiovascular system and its autonomic control.
In vitro bio-stability screening of novel implantable polyurethane elastomers
Authors: Kutuzova Larysa , Athanasopulu Kiriaki , Schneider Markus , Kandelbauer Andreas , Lorenz Günter , Kemkemer Ralf 
Published: September 2018

Abstract
A series of novel biomedical TPCUs with different percentages of hard segment and a silicone component in the soft segment were synthesized in a multi-stage one-pot method. The kinetic profiles of the urethane formation in TPCU-based copolymer systems were monitored by rheological, in line FTIR spectroscopic (React IR) and real-time calorimetric (RC1) methods. This process-analytically monitored multi step synthesis was successfully used to optimize the production of medical-grade TPCU elastomers on preparative scale (in lots of several kg) with controlled molecular structure and mechanical properties. Various surface and bulk analytical methods as well as systematic studies of the mechanic response of the elastomer end-products towards compression and tensile loading were used to estimate the bio-stability of the prepared TPCUs in vitro after 3 months. The tests suggested that high bio-stability of all polyurethane formulations using accelerating in vitro test can be attributed to the synthetic design as well as to the specific techniques used for specimen preparation, namely: (i) the annealing for reducing residual polymer surface stress and preventing IES, (ii) stabilization of the morphology by long-time storage of the specimens after processing bevor being immersed in the test liquids, (iii) purification by extraction to remove the shot chain oligomers which are the most susceptible to degradation. All mechanical tests were performed on cylindrical and circular disc specimens for modelling the thickness of the meniscus implants under application-relevant stress conditions.
Synchronized presentation of a language task to the electrical stimulation of cortical regions during speech mapping in an awake surgery
Authors: Hansmeyer Laura , Krueger Thilo B. 
Published: September 2018

Abstract
Intraoperative speech mapping is performed to preserve language function during tumour resections that involve eloquent cortical areas. For this technique the synchronization of the picture presentation to the patient with the electrical stimulation of the cortex is of major importance. During the operative routine images are manually presented by a psychologist or neurologist to the patient and have to be coordinated with the neurosurgeon stimulating the cortex by a neurostimulator, operated by an engineer. To increase the efficiency of this procedure and to minimize the time needed to localize functional cortical areas, images should appear automatically with electrical stimulation. To achieve this synchronization, the potential combination of an existing neurostimulator with commercially available software for image display was studied. A trigger signal was created to induce the presentation of a series of line drawings showing different objects. The software to control the neurostimulator and the software for image displaying were installed on two different computers. A cable was developed to transfer the trigger signal from the neurostimulator to the computer used for picture presentation. It was shown that it is possible to induce the image display via the neurostimulator using square-wave pulses of 5 V and a width of 10 ms. Thus, we present a system that enables the automated picture presentation synchronized to the electrical stimulation of cortical regions.