bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bi - Domain Intraoperative Registration of Vessels
Authors: Naber Ady , Nahm Werner 
Published: September 2018

Abstract
The segmentation and registration of structures are gaining importance due to the increasing demand of automated image enhancement and understanding. Especially in medicine and life science, assistance systems could have a large impact on diagnosis, treatment and quality control. Dye driven procedures, such as fluorescence imaging with Indocyanine green (ICG), are nowadays indispensable because they enhance contrast, reveal structures and deliver the operator with important information. The contact free ICG angiography is providing the surgeon spatial and temporal information on blood flow within a vessel. The processing of those information is done manually or semi automated but is very helpful for the surgeon. Extending the degree of automatism, the amount of information processed and even augment or transfer it into another domain could deliver the operator useful support and improve surgical work flow. Using, analyzing and transferring those information from ICG-IR domain into the RGB domain is the focus of this project. We are introducing a vessel registration method in the RGB domain driven by the spatial fluorescence behavior of the vessel in the ICG-IR domain. The method includes Superpixel based segmentation of the vessel in the ICG-IR domain, the spatial gradient based transfer and registration in the RGB domain and the continuous segmentation of the vessel in a RGB video. This paper show a proof of concept of the method. The results show an successful inter domain information transfer and registration of the vessel. Further tracking of the vessel over all frames is possible. Nevertheless limitations are revealed and discussed.
Mock loop for bubble generation in a centrifugal blood pump for fault simulation
Authors: Stollenwerk André , Buglowski Mateusz , Kühn Jan 
Published: September 2018

Abstract
In extracorporeal blood circulation intensive care treatments, the occurrence of gas within the circulation is one known major hazard. This gas volume can cause severe harm to the patient like infarctions. Consequently, within risk assessment for these treatments gas bubbles are usually addressed by either constructive or signal based approaches. All signal-based approaches do have in common that they need a sufficient amount of data to be parameterized. These data can only be acquired in animal trials or laboratory experiments, as they could result in harm to patients. Hence, we designed a mock loop, which is automatically able to create annotated data of gas bubbles injected into an extracorporeal circulation. We were able to run this setup with a periodicity of 15 seconds, which results in 240 annotated measurements per hour. For the evaluation, we created 1095 bubbles of varying sizes (0.3 to 0.5 ml). The elaborated setup enables us to produce a great amount of annotated data, which is shown to be comparable to manually generated data in a convenient and fully automated manner.
Low-cost physiological simulation system for endovascular treatment of aneurysms
Authors: Pfau Oskar , Kemmling André , Rostalski Philipp 
Published: September 2018

Abstract
Minimally invasive procedures are more and more becoming the standard treatment for many surgical procedures such as the treatment of cerebral aneurysms. In an endovascular procedure the aneurysm is filled with flexible platinum coils leading to embolization and blocking the blood flow in the aneurysm. This established treatment needs high skills and experience on the surgeon. In order to practice and plan a specific procedure or test a new device, a realistic simulation environment is needed. Modern 3D printing technology allows the fabrication of patient specific models incorporating the exact geometry of the pathological anatomy. This article describes the development of a low-cost physiological simulation system for the training of the endovascular treatment of aneurysms. In order to practice the procedure in a realistic scenario, a 3D printed model of the aneurysm is embedded in a fluidic simulation s ystem. In addition to the patient-specific anatomy of the aneurysm a pulsatile water flow is generated, which emulates the influence of blood flow on the behaviour of catheters and coils during deployment. The system consist of a controllable pump circuit generating a pulsatile flow which can be regulated automatically and additionally controlled externally by the user. For a suitable representation, a display which graphically represents the sensor data and settings is employed. The components were compactly integrated in a small case allowing for easy deployment in training workshops. The simulation setup was successfully tested in prospective patient specific treatment planning and workshops for students.
A drive mechanism for a blood pump integrated in an oxygenator
Authors: Aghababaei Amin , Kashefi Ali , Hexamer Martin 
Published: September 2018

Abstract
The achievement of a low priming volume of the components in an extracorporeal perfusion system for neonatal and pediatric patients is an open research question. This paper presents a concept of a pump-oxygenator in which an oxygenator and a pulsatile blood pump are combined in one housing. For operation of the pump-oxygenator, a special actuating system for the pump process was designed. It consists of a piston pump which is directly coupled with a voice coil actuator (VCA). A servo positioning system was developed to assure the piston motion according to predefined reference trajectories. First experimental results indicate the feasibility of driving this blood pump with a VCA. In an in-vitro study, the pump produced mean flow rates of 60-900 mL/min with stroke frequencies in the range of 60-240 beats per minute.
Proximally placed signal acquisition sensoric for robotic tissue tool interactions
Authors: Chen Chien-Hsi , Sühn Thomas , Illanes Alfredo , Maldonado Ivan , Ahmad Hesham , Wex Cora , Croner Roland , Boese Axel , Friebe Michael 
Published: September 2018

Abstract
Robotic surgeries are still limited with respect to the surgeon’s natural senses. The tactile sense is exceptional important in conventional clinical procedures. To identify critical structures inside the tissue, palpation is a commonly used technique in conventional open surgeries. The underlying organ or pathological structures conditions (healthy, abnormally hard or soft) can for example be localized and assessed through this process. Palpation needs a tactile sense; however, that is commonly not available or limited in robotic surgeries. The palpation need was already addressed by several research groups that integrated complex sensor-feedback-systems into prototype surgical instruments for robotic systems. We propose a new technique to acquire data of the tissue tool interaction of the surgical instruments. The structure borne transmission path is used to measure acoustic emission (AE) at the outpatient (proximal) end of the instruments with the help of different sensors attached to the surface of the surgical tool. Initial tests were performed using a microphone in combination with a stethoscope. This setup showed promising results and a more integrated prototype was subsequently designed. A piezoelectric charge accelerometer was used as vibration sensor and compared to a MEMS microphone. A signal acquisition system was developed to acquire signals from both sensors in parallel. The sensors were then attached onto the shaft of a daVinci Prograsp Forceps instrument. According to the surgery observation, a series of simulated experiments was conducted. The tip of the grasper was swiped manually over a human subject’s dorsal and palmar hand side, lateral side of neck and over the carotid artery. Additionally, contact with soft tissue and other instruments were evaluated since these are events of interest during surgery. Advanced signal processing techniques allowed the identification and characterization of significant events such as palpation dynamics, contact and pulsation. Signals acquired by the MEMS microphone showed the most promising results. This approach will now be used to build a prototype for further evaluation in a clinical setup. The paper presents the first results that show that this novel technique can provide valuable information about the tool-tissue interaction in robotic surgery that typically can only be obtained through advanced distal sensor systems or actual human touch.
Deep transfer learning for aortic root dilation identification in 3D ultrasound images
Authors: Hagenah Jannis , Heinrich Mattias , Ernst Floris 
Published: September 2018

Abstract
Pre-operative planning of valve-sparing aortic root reconstruction relies on the automatic discrimination of healthy and pathologically dilated aortic roots. The basis of this classification are features extracted from 3D ultrasound images. In previously published approaches, handcrafted features showed a limited classification accuracy. However, feature learning is insufficient due to the small data sets available for this specific problem. In this work, we propose transfer learning to use deep learning on these small data sets. For this purpose, we used the convolutional layers of the pretrained deep neural network VGG16 as a feature extractor. To simplify the problem, we only took two prominent horizontal slices throgh the aortic root, the coaptation plane and the commissure plane, into account by stitching the features of both images together and training a Random Forest classifier on the resulting feature vectors. We evaluated this method on a data set of 48 images (24 healthy, 24 dilated) using 10-fold cross validation. Using the deep learned features we could reach a classification accuracy of 84 %, which clearly outperformed the handcrafted features (71 % accuracy). Even though the VGG16 network was trained on RGB photos and for different classification tasks, the learned features are still relevant for ultrasound image analysis of aortic root pathology identification. Hence, transfer learning makes deep learning possible even on very small ultrasound data sets.
Optimization of stent designs regarding the thrombosis risk using computational fluid dynamics
Authors: Wüstenhagen Carolin , Pfensig Sylvia , Siewert Stefan , Kaule Sebastian , Grabow Niels , Schmitz Klaus-Peter , Stiehm Michael 
Published: September 2018

Abstract
In-stent thrombosis is a major complication of stent implantations. Unlike pathological occurrences as in-stent restenosis for instance, thrombosis represents an acute event associated with high mortality rates. Experiments show that low wall shear stress promotes undirected endothelial cell coverage of the vessel wall and therefore increases the risk of thrombus formation. Stent design represents a crucial factor influencing the surface areas of low wall shear stress and thus the incidence of acute in-stent thrombosis. In this study, we present an optimization method for stent designs with minimized thrombosis risk. A generic stent design was developed, based on five different stent design parameters. Optimization was conducted based on computational fluid dynamics analysis and the gradient-free Nelder-Mead approach. For each optimization step, a numerical fluid simulation was performed in a vessel with a reference vessel diameter of 2.70 mm with stent-overexpansion ratio of 1.0:1.1. For each numerical fluid simulation a physiological Reynolds number of 250, resulting in a mean velocity of 0.331 m/s at the inlet and a laminar flow as well as stiff vessel walls were assumed. The impact of different stent designs was analyzed based on the wall shear stress distribution. As a basis for the comparison of different stent designs, a dimensionless thrombosis risk number was calculated from the area of low wall shear stress and the overall stented area. The first two optimization steps already provide a decrease of thrombosis risk of approximately 83%. In conclusion, computational fluid dynamic analyses and optimization methods usind the Nelder-Mead approach represent a useful tool for the development of hemodynamically optimized stent designs with minimized thrombosis risk.
Heart phantom with electrical properties of heart muscle tissue
Authors: Korn Leonie , Lyra Simon , Rüschen Daniel , Pugovkin Alexander , Telyshev Dmitry , Leonhardt Steffen , Walter Marian 
Published: September 2018

Abstract
The weakened heart is supported by a left ventricular assist device (LVAD) to supply the heart muscle with oxygenated blood. In case the heart muscle recovers during LVAD therapy, the patient has to be weaned from the device. To date, there is no adequate method to detect heart muscle recovery in LVAD therapy. In order to establish a novel method based on the measurement of electric conductivity, this study presents a silicone model of a ventricle mock-up to simulate the electrical properties of cardiac muscle tissue. Previously, it has been shown that the electrical properties of myocardial tissue change during ischemia, so that these changes are a possible estimate for measuring the condition of myocardial tissue. To this purpose, this study presents a casting process for a ventricle model and describes the materials used to imitate the electrical properties of the heart muscle to obtain conductive material. Initial results showed that the higher the carbon concentration in the silicone, the higher the conductivity of the silicone samples. The measurements were performed at different frequencies and the samples were analyzed for homogenization.
Effects of local activation times on the tension development of human cardiomyocytes in a computational model
Authors: Müller Armin , Kovacheva Ekaterina , Schuler Steffen , Dössel Olaf , Baron Lukas 
Published: September 2018

Abstract
The human heart is an organ of high complexity and hence, very challenging to simulate. To calculate the force developed by the human heart and therefore the tension of the muscle fibers, accurate models are necessary. The force generated by the cardiac muscle has physiologically imposed limits and depends on various characteristics such as the length, strain and the contraction velocity of the cardiomyocytes. Another characteristic is the activation time of each cardiomyocyte, which is a wave and not a static value for all cardiomyocytes. To simulate a physiologically correct excitation, the functionality of the cardiac simulation framework CardioMechanics was extended to incorporate inhomogeneous activation times. The functionality was then used to evaluate the effects of local activation times with two different tension models. The active stress generated by the cardiomyocytes was calculated by (i) an explicit function and (ii) an ode-based model. The results of the simulations showed that the maximum pressure in the left ventricle dropped by 2.3% for the DoubleHill model and by 5.3% for the Lumens model. In the right ventricle the simulations showed similar results. The maximum pressure in both the left and the right atrium increased using both models. Given that the simulation of the inhomogeneously activated cardiomyocytes increases the simulation time when used with the more precise Lumens model, the small drop in maximum pressure seems to be negligible in favor of a simpler simulation model.
Context-aware medical technologies - relief or burden for clinical users?
Authors: Neumuth Thomas , Rockstroh Max , Franke Stefan 
Published: September 2018

Abstract
The open, cross-vendor interoperability of medical devices is an enabling technology for the implementation of context-aware biomedical systems in daily clinical routine. The surgical working environment is both a valuable field of application and a particular challenge. A design of context-aware medical technologies that shows intelligent behaviour and ensures safe operation is demanding; thus implementations are yet limited to prototypes and specific surgical use cases. Many open research questions need to be addressed to empower context-aware medical systems to be a relief and not a burden for the clinical user.
Novel 3D printing concept for the fabrication of time-controlled drug delivery systems
Authors: Konasch Jan , Riess Alexander , Teske Michael , Rekowska Natalia , Rekowska Natalia , Mau Robert , Eickner Thomas , Grabow Niels , Seitz Hermann 
Published: September 2018

Abstract
Three-dimensional (3D) printing has become a popular technique in many areas. One emerging field is the use of 3D printing for the development of 3D drug delivery systems (DDS) and drug-loaded medical devices. This article describes a novel concept for the fabrication of timecontrolled drug delivery systems based on stereolithography combined with inkjet printing. An inkjet printhead and an UV-LED light source have been integrated into an existing stereolithography system. Inkjet printing is used to selectively incorporate active pharmaceutical ingredients (API) during a stereolithographic 3D printing process. In an initial experimental study, poly (ethylene glycol) diacrylate (PEGDA) was used as polymer whereas 2-Hydroxy-4´-(2- hydroxyethoxy)-2-methylpropiophenone (Irgacure 2959) and Lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) were used as photoinitiators. Basic structures could be manufactured successfully by the new hybrid 3D printing system.
Assessment of Natural User Interactions for Robot-Assisted Interventions
Authors: Berger Johann , Unger Michael , Landgraf Lisa , Bieck Richard , Neumuth Thomas , Melzer Andreas 
Published: September 2018

Abstract
Robotic assistance in clinical interventions provides high precision and performance. However, the acceptance of such systems is still very low. The idea of collaborative robotics promises practical solutions for this problem. To further promote these ideas in the medical domain, novel concepts for user interactions are needed. This work presents a preliminary study on the recognition accuracy of touch gesture interaction with a KUKA LBR iiwa robotic arm. A recognition application utilising a set of 4 different touch gestures was implemented and evaluated by eight participants. The overall recognition accuracy of the system is 89.8%.
Optical strain measurement for the modeling of surgical meshes and their porosity
Authors: Horbach Andreas J. , Staat Manfred 
Published: September 2018

Abstract
The porosity of surgical meshes makes them flexible for large elastic deformation and establishes the healing conditions of good tissue in growth. The biomechanic modeling of orthotropic and compressible materials requires new materials models and simulstaneoaus fit of deformation in the load direction as well as trannsversely to to load. This nonlinear modeling can be achieved by an optical deformation measurement. At the same time the full field deformation measurement allows the dermination of the change of porosity with deformation. Also the socalled effective porosity, which has been defined to asses the tisssue interatcion with the mesh implants, can be determined from the global deformation of the surgical meshes.
Biomechanics of a novel extra-articular implant for younger patients with knee osteoarthritis
Authors: Saeidi Mehdi , Ramezani Maziar , Kelly Piaras , Hussin Mohd Sabri , Neitzert Thomas 
Published: September 2018

Abstract
This research aimed to study the efficacy of a novel implant for osteoarthritic knees. This implant is designed to eliminate excessive loads through the knee and to provide suitable conditions for possible tibiofemoral cartilage regeneration. The implant was designed for the medial side of the knee joint. Finite Element Analysis (FEA) was performed for an extended knee position of the knee joint. Contact pressure distributions on the medial and lateral compartments were investigated as well as stress distributions throughout the implant’s plates. Results with and without the implant were compared, and it was seen that the contact pressures on the surface of the distal femur were reduced by more than 90% after the introduction of the implant.
Polymer drug release system for biofilm inhibition in medical application
Authors: Wulf Katharina , Arbeiter Daniela , Eickner Thomas , Riedel Katharina , Schmitz Klaus-Peter , Grabow Niels , Kohse Stefanie 
Published: September 2018

Abstract
Bacterial biofilm formation on surfaces is still a critical challenge regarding the application of implants. Generally, in order to avoid this, an additional systemic administration of antibiotics is given, which can lead to side effects, such as the reduction of the intestinal flora. Continuous treatment may lead to antibiotics resistance. Within this study we investigated the local drug delivery of N-acetyl-L-cysteine (NAC) from a Poly-L-lactide (PLLA) coating, an ished biodegradable polymer and a polyetherurethane (PEU) coating, a promising representative non-degradable polymer for cardiovascular applications as alternative to the administration of antibiotics. The incorporation of NAC influenced the surface properties of PEU in contrast to that of PLLA. The in vitro NAC release is almost completed after 24 h for PEU. For PLLA only small amounts of incorporated NAC, depending on the NAC loading, is released after a short time. Both systems are rather useful as local NAC delivery system directly after implantation.
Polyelectrolyte Coatings for Surface Modification of Medical Implants
Authors: Krastev Rumen , Rudt Alexander , Xiong Xin , Hartmann Hanna 
Published: September 2018

Abstract
Polyelectrolyte multi-layer (PEM) coatings are prepared by alternative deposition of single polyelectrolyte monolayers on charged surfaces using the Layer-by-Layer (LbL) dip coating procedure. These are nanometre scaled coatings which allow fulfilling of different technical or biological requirements. The build-up process is based on selfassembly and self-organization of polycations and polyanions on different substrates including complex geometrical structures and even closed volumes, forming homogeneous layer without defects. Depending on the proper selection of the applied polyelectrolytes, coatings with different stabilities can be prepared. Some of the coatings are stable and cannot be removed from the surface. Others are degradable and can be used as systems for controlled local drug delivery. Here we summarise the results of our experience in preparation of PEM coatings with different functionalities. PEM coatings can be used as controllable delivery system for siRNA polyplexes. They can be used to control the adhesion of different cell types on the surfaces and support e.g. the endothelialisation process on cardio-vascular medical devices as e.g. stents or reduce the immunological response of the tissue after implantation. We summarise results from physical characterisation of the coatings (e.g. film thickness, roughness, electrical charge and hydrophilicity) combined with in-vitro biological studies on adhesion of HUVEC cells.
Accelerated in vitro-calcification of potential urethane based heart valve replacement materials
Authors: Oschatz Stefan , Kohse Stefanie , Senz Volkmar , Eickner Thomas , Schmitz Klaus-Peter , Grabow Niels 
Published: September 2018

Abstract
Polycarbonate urethane and polyether urethane nonwovens as promising representatives of novel polymer heart valve materials were analysed regarding the susceptibility to calcification in comparison to porcine pericardium and polyamide 6. The applied method represents an accelerated calcification out of a metastable solution in short time with significant precipitates on the reference material. As our results show, urethane based nonwoven structures exhibit considerably lower susceptibility to calcification compared to pericardium as widely established material for leaflet design.