bluuebunny/crossref_metadata_2025_split huggingface dataset:
Kinect based physiotherapy system for home use
Authors: Haas Dominik , Phommahavong Somphong , Yu Jing , Krüger-Ziolek Sabine , Möller Knut , Kretschmer Jörn 
Published: September 2015

Abstract
In physiotherapy, rehabilitation outcome is majorly dependent on the patient continuing exercises at home. To support a continuous and correct execution of exercises composed by the physiotherapist it is important that the patient stays motivated. With the emergence of game consoles such as Nintendo Wii, Sony PlayStation or Microsoft Xbox360 that employ special controllers or camera based motion recognition as means of user input those technologies have also been found to be interesting for other real-life applications. We present a concept to employ the Microsoft Kinect system as means to support patients during physiotherapy exercises at home. The system is intended to allow a physiotherapist to compose an individual set of exercises and to control the correct execution of those exercises through tracking the patient’s motions.
Measurement of needle susceptibility artifacts in magnetic resonance images
Authors: Schmitt Sebastian , Skopnik Katharina , Overhoff Heinrich Martin 
Published: September 2015

Abstract
The success of minimally invasive procedures under MR-guidance can be increased by the knowledge of the current needle pose. We hypothesize that a one-toone mapping exists between the needle orientation with respect to the static magnetic field and the cross-sectional shape of the needle’s susceptibility artifact. For this purpose, we derived a mathematical model, which describes the cross sectional geometry of the needle artifact. It is approximated by two ellipses. Certain parameters of these ellipses can be utilized for mapping the geometry of the needle artifact onto the needle orientation. The relation between the two ellipse parameters α (inclination of the semi-major axis) and b (length of the semi-minor axis) and the needle’s azimuth angle can be approximated by linear regression in a certain angle interval. A combination of these two ellipse parameters is suitable for estimating the needle’s azimuth angle within a range between 0° and 60°.
Dimensionality reduction of medical image descriptors for multimodal image registration
Authors: Degen Johanna , Modersitzki Jan , Heinrich Mattias P. 
Published: September 2015

Abstract
Defining similarity forms a challenging and relevant research topic in multimodal image registration. The frequently used mutual information disregards contextual information, which is shared across modalities. A recent popular approach, called modality independent neigh-bourhood descriptor, is based on local self-similarities of image patches and is therefore able to capture spatial information. This image descriptor generates vectorial representations, i.e. it is multidimensional, which results in a disadvantage in terms of computation time. In this work, we present a problem-adapted solution for dimensionality reduction, by using principal component analysis and Horn’s parallel analysis. Furthermore, the influence of dimensionality reduction in global rigid image registration is investigated. It is shown that the registration results obtained from the reduced descriptor have the same high quality in comparison to those found for the original descriptor.
Towards contactless optical coherence elastography with acoustic tissue excitation
Authors: Düwel Dino , Otte Christoph , Schulz Kevin , Saathoff Thore , Schlaefer Alexander 
Published: September 2015

Abstract
Elastography presents an interesting approach to complement image data with mechanical tissue properties. Typically, the tissue is excited by direct contact to a probe. We study contactless elastography based on optical coherence tomography (OCT) and dynamic acoustic tissue excitation with airborne sound. We illustrate the principle and an implementation using sound waves of 135 Hz to excite the tissue. The displacement is measured and results of several tests indicate the feasibility to obtain a qualitative measure of the mechanical tissue properties. The approach is interesting for optical palpation, e.g., to enhance navigation and tissue characterization in minimally invasive and robot-assisted surgery.
Development and implementation of algorithms for automatic and robust measurement of the 2D:4D digit ratio using image data
Authors: Koch Robert , Haßlmeyer Erik , Tantinger Daniel , Rulsch Martin , Weigand Christian , Struck Matthias 
Published: September 2015

Abstract
Early in the 20th century it could be observed that the finger lengths of second (2D) and fourth digit (4D) represents a sexually dimorphic feature, whereby in general the second digit is longer than the fourth digit for men and vice versa for women. In the early 1980s first studies could show a correlation between the 2D:4D ratio and the concentration of androgens one is exposed to during a short window within the prenatal development phase. Therefore, the 2D:4D digit ratio can serve as an additional marker for certain physiological and psychological traits like fertility, assertiveness, aggressiveness and alcohol addiction. Manual measurements are the established method to retrieve the finger lengths e.g. by using a ruler on printed scans of hands. For higher reliability these extremely time-consuming procedures have to be done multiple times. In this contribution two automated procedures are proposed to reduce the time for measurements whilst maintaining the accuracy. A deviation of maximal 2% from the manual measurement could be achieved for more than 75% of the 22 participants.
Video tracking of swimming rodents on a reflective water surface
Authors: Christ Olaf , Hofmann Ulrich G. 
Published: September 2015

Abstract
Animal models are an essential testbed for new devices on their path from the bench to the patient. Potential impairments by brain stimulation are often investigated in water mazes to study spatial memory and learning. Video camera based tracking systems exist to quantify rodent behaviour, but reflections of ambient lighting on the water surface and artefacts due to the waves caused by the swimming animal cause errors. This often requires tweaking of algorithms and parameters, or even potentially modifying the lab setup. In the following, we provide a simple solution to alleviate these problem using a combination of region based tracking and independent multimodal background subtraction (IMBS) without hav ing to tweak a plethora of parameters.
Artifacts in field free line magnetic particle imaging in the presence of inhomogeneous and nonlinear magnetic fields
Authors: Medimagh Hanne , Weissert Patrick , Bringout Gael , Bente Klaas , Weber Matthias , Gräfe Ksenija , Cordes Aileen , Buzug Thorsten M. 
Published: September 2015

Abstract
Introduction: Magnetic Particle Imaging (MPI) is an emerging medical imaging modality that detects super-paramagnetic particles exploiting their nonlinear magnetization response. Spatial encoding can be realized using a Field Free Line (FFL), which is generated, rotated and translated through the Field of View (FOV) using a combination of magnetic gradient fields and homogeneous excitation fields. When scaling up systems and/or enlarging the FOV in comparison to the scanner bore, ensuring homogeneity and linearity of the magnetic fields becomes challenging. The present contribution describes the first comprehensive, systematic study on the influence of magnetic field imperfections in FFL MPI. Methods: In a simulation study, 14 different FFL scanner setups have been examined. Starting from an ideal scanner using perfect magnetic fields, defined imperfections have been introduced in a range of configurations (nonlinear gradient fields, inhomogeneous excitation fields, or inhomogeneous receive fields, or a combination thereof). In the first part of the study, the voltage induced in the receive channels parallel and perpendicular to the FFL translation have been studied for discrete FFL angles. In the second part, an imaging process has been simulated comparing different image reconstruction approaches. Results: The induced voltage signals demonstrate illustratively the effect of the magnetic field imperfections. In images reconstructed using a Radon-based approach, the magnetic field imperfections lead to pronounced artifacts, especially if a deconvolution using the point spread function is performed. In images reconstructed using a system function based approach, variations in local image quality become visible. Conclusion: For Radon-based image reconstruction in FFL MPI in the presence of inhomogeneous and nonlinear magnetic fields, artifact correction methods will have to be developed. In this regard, a first approach has recently been presented by another group. Further research is required to elucidate the influence of magnetic field imperfections in MPI using a system function based approach.
Intravascular optical coherence tomography (OCT) as an additional tool for the assessment of stent structures
Authors: Hoffmann Thomas , Boese Axel , Glaßer Sylvia , Skalej Martin , Beuing Oliver 
Published: September 2015

Abstract
Evaluation of the vascular stent position, shape and correct expansion has a high relevance in therapy and diagnosis. Hence, the wall apposition in vessel areas with differing diameters and the appearance of torsions or structural defects of the implant body caused by catheter based device dropping are of special interest. Neurovascular implants like braided flow diverter and laser cut stents consist of metal struts and wires with diameters of about 40 µm. Depending on the implants material composition, visibility is poor with conventional 2D X-ray fluoroscopic and radiographic imaging. The metal structures of the implants also lead to artifacts in 3D X-ray images and can hamper the assessment of the device position. We investigated intravascular optical coherence tomography (OCT) as a new imaging tool for the evaluation of the vascular stent position, its shape and its correct expansion for 3 different vascular implants.
Simple concept for a wide-field lensless digital holographic microscope using a laser diode
Authors: Adinda-Ougba A. , Koukourakis N. , Gerhardt N. C. , Hofmann M. R. 
Published: September 2015

Abstract
Wide-field, lensless digital holographic microscopy is a new microscopic imaging technique for telemedicine and for resource limited setting [1]. In this contribution we propose a very simple wide-field lensless digital holographic microscope using a laser diode. It is based on in-line digital holography which is capable to provide amplitude and phase images of a sample resulting from numerical reconstruction. The numerical reconstruction consists of the angular spectrum propagation method together with a phase retrieval algorithm. Amplitude and phase images of the sample with a resolution of ∽2 µm and with ∽24 mm2 field of view are obtained. We evaluate our setup by imaging first the 1951 USAF resolution test chart to verify the resolution. Second, we record holograms of blood smear and diatoms. The individual specimen can be easily identified after the numerical reconstruction. Our system is a very simple, compact and low-cost possibility of realizing a microscope capable of imaging biological samples. The availability of the phase provide topographic information of the sample extending the application of this system to be not only for biological sample but also for transparent microstructure. It is suitable for fault detection, shape and roughness measurements of these structures.
Respiratory surface motion measurement by Microsoft Kinect
Authors: Ortmüller J. , Gauer T. , Wilms M. , Handels H. , Werner R. 
Published: September 2015

Abstract
In radiotherapy of abdominal and thoracic tumors, respiratory motion is a problem for an accurate treatment. Most current motion compensation techniques rely on externally acquired breathing signals of the patient. The systems in clinical use usually work with 1D surface motion signals to describe internal structure respiratory motion patterns. As a 1D signal is not able to describe complex motion patterns and breathing variations, in this work the Microsoft Kinect, which can record multidimensional respiratory surface motion signals, is proposed to be used instead. For the Kinect, a clinically acceptable measurement setup is designed and Kinect measurements are compared to the Varian RPM system (clinical standard). The results show that the signals are well aligned. An additional comparison of Kinect signals from different regions of interest on the chest further reveals variations between them. This illustrates that the use of a system that provides multidimensional signals is worthwhile; the knowledge about breathing variations could be applied for optimization of current clinical workflows.
Experimental computer tomograph
Authors: Heinemann D. , Keller A. , Jannek D. 
Published: September 2015

Abstract
The computed tomography is one of the most important medical instruments, allowing the non-invasive visualization of cross sections which are free from superpositions. Since 2000 an experimental computer tomo-graph of the third generation for the purpose of education and research was set up and further developed. Besides the mechanical construction design reconstruction algorithms, including certain corrections of the measured data were developed and implemented. In 2013 iterative reconstruction methods were investigated and implemented for advanced reconstructions and dose reduction using various ray tracing algorithms. The new reconstruction technique leads to improvements in image quality and low dose reconstructions.
Contribution of brownian rotation and particle assembly polarisation to the particle response in magnetic particle spectrometry
Authors: von Gladiss Anselm , Graeser Matthias , Lüdtke-Buzug Kerstin , Buzug Thorsten M. 
Published: September 2015

Abstract
The spectrometry of super-paramagnetic iron-oxide nanoparticles is a central tool for characterising particles that are used in Magnetic Particle Imaging. In Magnetic Particle Imaging, nanoparticles are excited by a magnetic field and the particle response is measured. Until now, the influence of the trajectory sequence on the dynamic particle relaxation has not been scoped. With a multi-dimensional Magnetic Particle Spectrometer, analysing the behaviour of different trajectories on the particles becomes possible. In this paper, the contribution of Brownian rotation and assembly polarisation on the particle signal is being analysed.
Construction of a device for magnetic separation of superparamagnetic iron oxide nanoparticles
Authors: Kläser Kerstin , Graeser Matthias , Steinhagen Dirk , Luedtke-Buzug Kerstin 
Published: September 2015

Abstract
Suspensions of iron oxide particles, so called ferrofluids, are successfully used in various technical, biochemical and medical applications. For example they find use in the area of sensor engineering, magnetic resonance imaging (MRI) and especially magnetic particle imaging (MPI). MPI is a new tomographic imaging technique that determines the spatial distribution of superparamagnetic iron oxide nanoparticles (SPIONs). Besides a very high spatial and temporal resolution MPI provides quantitative realtime imageing. The nanoparticles cause a magnetization change that can be measured. As the particle size distribution has a huge impact on the magnetization behavior is an important parameter for optimization. While synthesizing, SPIONs particles with various dimensions are formed what necessitates a systematically separation by size. For this purpose a construction of a simple device for magnetic separation of SPIONs has been developed. First attemps of separation show the potential of this method.
Automated respiratory therapy system based on the ARDSNet protocol with systemic perfusion control
Authors: Pomprapa Anake , Walter Marian , Braun Wolfgang , Lachmann Burkhard , Leonhardt Steffen 
Published: September 2015

Abstract
A medical expert system of automatic artificial ventilation is set up in a star topology with additional closed-loop hemodynamic control. Arterial blood pressure (MAP) is controlled by noradrenaline (NA) as a controlling variable. The overall patient-in-the-loop expert system can intensively and intelligently perform a long-term treatment based on the Acute Respiratory Distress Syndrome Network (ARDSNet) protocol. Three main goals are actively carried out, namely the stabilization and regulation of oxygenation, plateau pressure and blood pH value. The developed system shows a distinctive experimental result based on a 31.5-kg pig, in order to fulfil the ventilatory goals and to ensure proper systemic perfusion. Hence, this system has enormous potentials to realize a commercial system for individual patient with ARDS.
A generic concept for the development of model-guided clinical decision support systems
Authors: Denecke Kerstin , Chalopin Claire 
Published: September 2015

Abstract
Disease development and progression are very complex processes which make clinical decision making non-trivial. On the one hand, examination results that are stored in multiple formats and data types in clinical information systems need to be considered. Beyond, biological or molecular-biological processes can influence clinical decision making. So far, biological knowledge and patient data is separated from each other. This complicates inclusion of all relevant knowledge and information into the decision making. In this paper, we describe a concept of model-based decision support that links knowledge about biological processes, treatment decisions and clinical data. It consists of three models: 1) a biological model, 2) a decision model encompassing medical knowledge about the treatment workflow and decision parameters, and 3) a patient data model generated from clinical data. Requirements and future steps for realizing the concept will be presented and it will be shown how the concept can support the clinical decision making.
Evaluation of local alterations in femoral bone mineral density measured via quantitative CT
Authors: Sitzer A. , Aulmann L. , Wendlandt R. , Handels H. , Weyers I. , Schulz A. P. , Buzug T. M. 
Published: September 2015

Abstract
The aim of this study was to investigate the accuracy of bone mineral density (BMD) determined by quantitative computed tomography (qCT) based on in situ and ex situ scans of cadavers of variable stature. The influence of surrounding tissue on the quantification of CT images of ex situ scanned femora was investigated in air and in water and compared with the in situ scanned femora. The study showed that the surrounding tissue has an impact on the grey value-based representation of the scanned object as well as on the calibration of BMD, influencing the determination of BMD. Local differences in BMD of up to 17.5% were observed, which might originate from beam hardening artifacts.
A machine learning approach for planning valve-sparing aortic root reconstruction
Authors: Hagenah J. , Scharfschwerdt M. , Schlaefer A. , Metzner C. 
Published: September 2015

Abstract
Choosing the optimal prosthesis size and shape is a difficult task during surgical valve-sparing aortic root reconstruction. Hence, there is a need for surgery planning tools. Common surgery planning approaches try to model the mechanical behaviour of the aortic valve and its leaflets. However, these approaches suffer from inaccuracies due to unknown biomechanical properties and from a high computational complexity. In this paper, we present a new approach based on machine learning that avoids these problems. The valve geometry is described by geometrical features obtained from ultrasound images. We interpret the surgery planning as a learning problem, in which the features of the healthy valve are predicted from these of the dilated valve using support vector regression (SVR). Our first results indicate that a machine learning based surgery planning can be possible.
Measuring different oxygenation levels in a blood perfusion model simulating the human head using NIRS
Authors: Rackebrandt K. , Gehring H. 
Published: September 2015

Abstract
The oxygenation, perfusion and metabolism of the brain - segmented in both hemispheres - can be estimated from the oxygenation and hemoglobin levels of the venous blood in the cerebral efferent vessels.
We present a phantom based model to simulate the anatomical target region which was connected to hemodynamic perfusion circuit to provide different oxygenation rates inside of the simulated target vessel (measurement cell) reproducible. A triple-wavelength (770, 808 and 850 nm) multi-distance NIRS sensor (6 photodiodes, linearly arranged, separated 6 mm each) was used to detect these different saturation levels.
The results illustrate the capability to measure the optical property variation of hemoglobin due to oxygenation and deoxygenation processes in a specific vessel. Based on these first results a series of measurements is introduced to correlate the amount of reflected light to the actual oxygen saturation of the blood.
Multisegmental fusion of the lumbar spine a curse or a blessing?
Authors: Bauer S. , Paulus D. 
Published: September 2015

Abstract
Excessive mechanical load of the spinal structures during unfavorable movements in daily life can lead to degenerative damages especially of the lumbar spine. If the affected structures are damaged in such a way that conventional therapy does not improve the situation, often a surgery is unavoidable. One surgical method is the fusion of the affected spinal segments. In particularly difficult cases, the fusion may even extend over more than one functional spinal unit. An appropriate method for the estimation of the biomechanical effects of such interventions to adjacent vertebral segments is the computer simulation. This paper presents a 3D-MultiBodySimulation(MBS-) model of the lumbar spine with realistic surfaces and included intersegmental discs as well as ligamental structures. For these elements the physical behavior like force-deformation relations and characteristic curves for the torque-angle relations are formulated. The facet joints are modeled as cartilage, in order to simulate the contact between the corresponding articular surfaces. With this simulation, the effects of mono- and multisegmental fusions to the lumbar structures can be analyzed. The comparison of the simulations shows a redistribution of loads within the intervertebral discs. In the simulation case of monosegmental spinal fusion, the intervertebral disc below the fused segment are more loaded than in the simulated healthy state. The validation of the model was carried out by comparing the results with FE-simulations, various of vitro experiments and experimental data from biomedical literature.
Mathematical, numerical and in-vitro investigation of cooling performance of an intra-carotid catheter for selective brain hypothermia
Authors: Wolfertz J. , Meckel S. , Guber A. , Cattaneo G. 
Published: September 2015

Abstract
Therapeutic hypothermia (TH) has become an established neuroprotective therapy for patients after cardiac arrest [1, 2]. Selective brain cooling represents a promising way to shorten the time to reach the target brain temperature and additionally spare other organs from damage caused by temperature decrease. We present the investigation of the cooling performance of a single-balloon catheter dimensioned for the placement within the common carotid artery (CCA) by means of three different approaches: mathematical, numerical and in-vitro testing.