bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assessing the impact of a structural prior mask on EIT images with different thorax excursion models
Authors: Chen Rongqing , Battistel Alberto , Krueger-Ziolek Sabine , Chase James Geoffrey , Rupitsch Stefan J. , Moeller Knut 
Published: September 2023

Abstract
Electrical Impedance Tomography (EIT) has shown promising results as a low-cost imaging method for visualizing ventilation distribution within the lungs. However, clinical interpretation of EIT images is often hindered by blurred anatomical alignment and reconstruction artifacts. Integrating structural priors into the EIT reconstruction process has the potential to enhance the interpretability of the EIT images. Thus, a patient-specific structural prior mask is introduced in this contribution, which restricts the reconstruction of conductivity changes within the lung regions.We conducted numerical simulations on four finite element models representing four different thorax excursions to investigate the impact of the structural prior mask on EIT images. Simulations were performed under four different ventilation statuses. EIT images were reconstructed using the Gauss-Newton and discrete cosine transform-based EIT algorithms.We conducted a quantitative analysis using figures of merit to evaluate the images of the two reconstruction algorithms. The results show the structural prior mask preserves the morphological structures of the lungs and limits reconstruction artifacts.
Fallopian tube occlusion – anatomical ex vivo studies in advance of preclinical in vivo models for future microstent-based therapeutic concept evaluation
Authors: Stahnke Thomas , Dierke Ariane , Strübing Julia , Khaimov Valeria , Rosam Paula , Kruse Christine , Stiehm Michael , Wree Andreas , Muzzio Damián , Normann Nicole , Bock Andrea , Siewert Stefan , Schmitz Klaus-Peter , Zygmunt Marek 
Published: September 2023

Abstract
An unfulfilled pregnancy is often due to impaired patency of the female Fallopian tubes. To circumvent tubal obstruction, cost-intensive in vitro fertilisation (IVF) is currently indicated. The only therapeutic treatment concepts available are transvaginal tubal lavage/catheterization or laparoscopy with minimally invasive or complex surgical tubal reconstruction, which are associated with side effects. The development of new and cost-effective non- or minimally invasive therapeutic concepts that can restore the patency of the Fallopian tubes would be key in the treatment of female infertility and can fulfil the desire to have children. Therefore, in the present work, ex vivo anatomical studies are carried out on various laboratory mammals (pigs, rabbits, guinea pigs). Using these animal models, it was also evaluated whether a sensor-ureterorenoscope can be inserted through the whole female reproductive tract to the Fallopian tubes. This device will be used for endoscopically guided implantation of a novel tubal microstent prototype via its tailor-made delivery system into the isthmus region of the Fallopian tubes in upcoming studies. This work serves to identify an optimal species for a longitudinal animal study, in which the feasibility as well as the tissue reaction to the implant will be evaluated.
Unsupervised GAN epoch selection for biomedical data synthesis
Authors: Böhland Moritz , Bruch Roman , Löffler Katharina , Reischl Markus 
Published: September 2023

Abstract
Supervised Neural Networks are used for segmentation in many biological and biomedical applications. To omit the time-consuming and tiring process of manual labeling, unsupervised Generative Adversarial Networks (GANs) can be used to synthesize labeled data. However, the training of GANs requires extensive computation and is often unstable. Due to the lack of established stopping criteria, GANs are usually trained multiple times for a heuristically fixed number of epochs. Early stopping and epoch selection can lead to better synthetic datasets resulting in higher downstream segmentation quality on biological or medical data. This article examines whether the Frechet Inception Distance (FID), the Kernel Inception Distance (KID), or the WeightWatcher tool can be used for early stopping or epoch selection of unsupervised GANs. The experiments show that the last trained GAN epoch is not necessarily the best one to synthesize downstream segmentation data. On complex datasets, FID and KID correlate with the downstream segmentation quality, and both can be used for epoch selection.
Domain Transfer in Histopathology using Multi-ProtoNets with Interactive Prototype Adaptation
Authors: Kletzander Rosalie , Kuritcyn Petr , Bruns Volker , Eckstein Markus , Geppert Carol , Hartmann Arndt , Benz Michaela 
Published: September 2023

Abstract
Few-shot learning addresses the problem of classification when little data or few labels are available. This is especially relevant in histopathology, where labeling must be carried out by highly trained medical experts. Prototypical Networks promise transferability to new domains by using a pre-trained encoder and classifying by way of a prototypical representation of each class learned with few samples. We examine the applicability of this approach by attempting domain transfer from colon tissue (for training the encoder) to urothelial tissue. Furthermore, we address the problems arising from representing a class via a small amount of representatives (prototypes) by testing two different prototype calculation strategies. We compare the original “Prototype per Class” (PPC) approach to our “Prototype per Annotation” (PPA) method, which calculates one prototype for each example annotation made by the pathologist. We test the domain transfer capability of our approach on a dataset of 55 whole slide images (WSIs) containing six subtypes of urothelial carcinoma in two granularities: “Superclasses”, which combines the tumorous subtypes into a single “tumor” class on top of a aggregated “healthy” and additional “necrosis” class, and “subtypes”, which considers all eleven classes separately. We evaluate the classic PPC approach as well as our PPA approach on this data set. Our results show that the adaptation of the Prototypical Network from colon tissue to urothelial tissue was successful, yielding an F1 score of 0.91 for the “superclasses”. Furthermore, the PPA approach performs very comparably to the PPC strategy. This makes it a viable alternative that places more value on the intent of the pathologist during annotation.
Comparison of steady-state and transient flow measurements for the characterization of paravalvular leakage of transcatheter-aortic valve prostheses
Authors: Kaule Sebastian , Stiehm Michael , Siewert Stefan , Öner Alper , Schmitz Klaus-Peter , Borowksi Finja 
Published: September 2023

Abstract
Severe aortic valve stenosis has been successfully treated with minimally invasive transcatheter aortic valve replacement (TAVR) for more than 20 years. The therapy is applied to an increasing cohort of patients. Nevertheless, paravalvular leakage (PVL) remains one of the main complications after TAVR implantation reducing safety and efficacy of the implant. To improve TAVR performance, virtual patient cohorts can be used to generate a significant amount of data with biologically varying conditions comparable to clinically realworld data. For this purpose, in silico models need to be established which are used to evaluate the possible occurrence of PVL. When establishing in silico models, the question between simplification to reduce computational effort and still valid information from the model must always be clarified. Thus, we investigated the comparability between steadystate and transient PVL measurements as an input parameter for simulations in virtual cohorts. A clinically established TAVR was implanted into different annulus models and tested in a steady-state back-flow test bench and in a pulse duplicator system. As a result, leakage rates were compared and assumptions for the in silico models were derived. Although the trend of PVL is comparable in steady-state and transient conditions, absolute values differ making it difficult to extract generalized assumptions. Especially when PVL increased, e.g. in a larger implantation diameter or in an imperfect annulus, the variation also increased up to 50% of the measured value.
Evaluation of flushing parameters for clear view vascular endoscopy
Authors: Böckmann Julian , Klebingat Stefan , Schwab Roland , Behme Daniel , Boese Axel 
Published: September 2023

Abstract
Vascular diseases like aneurysms or atherosclerosis belong to the leading causes of death. For diagnosis and treatment, medical imaging is essential. Standard imaging methods are Ultrasound, X-ray-based Angiography, Computed tomography or Magnet Resonant Imaging. Additionally, Intravascular Ultrasound or Optical Coherence Tomography are available for intravascular imaging. One imaging technique for direct investigation of the inner vessel is vascular endoscopy, also called angioscopy. It is based on the insertion of an optical endoscope into the blood vessel for direct imaging. Dependent on the vessel diameter, these endoscopes have to be very small. Angioscopy can provide valuable information about the condition of the vessel wall and serve for procedure observation or implant assessment. But angioscopy requires the absence of blood for a clear field of view. In prior research, we have already developed methods for the placement of a tiny optical fiber inside a catheter combination. As an essential step toward a clinical study, we now want to evaluate the flushing parameters needed to achieve a clear field of view for the endoscope. The parameters are affected by the blood flow and vessel diameter. We designed a test setup that allows angioscopic examination and the simulation of realistic conditions, such as blood flow and different vessel diameters and that includes a test pattern for image quality assessment.
Training and education of young physicians and engineers in the field of endoscopy and laparoscopy – a review of Germany-wide joint cooperation and training possibilities
Authors: Wichmann Dörte , Duckwort-Mothes Benedikt , Hirt Bernhard , Wilhelm Dirk , Steger Jana , Zweimüller Martin , Küllmer Armin , Raithel Martin , Maiss Jürgen , Pott Peter , Wittenberg Thomas 
Published: September 2023

Abstract
Introduction: Application-related (hands-on) training and instruction is an essential component in the advanced education of physicians in residency. To teach and train required endoscopic examinations and interventions in a standardized manner, courses are offered by various societies. Within these courses the assistant endoscopists learn and train how to use the technical equipment and how to perform the examinations and related interventions. Similarly, for graduate biomedical engineering students with a job- or research-related interest in the field of endoand laparoscopy, an early involvement and practical introduction to the instrumentation and techniques - if possible already during their studies - can generate a fundamental understanding of the technical requirements as well needs of the physicians. Objective: As various such (hands-on) training-courses for flexible and rigid endoscopy specifically addressing young physicians, surgeons as well as engineers are offered by numerous institutes, this contribution tries do provide a structured overview on/over these possibilities. Material: Known cross-institutional courses in the field of endo- and laparoscopy currently offered in Germany in cooperation of physicians and engineers are listed and briefly described. Results: A total of n = 4 crossinstitutional courses for the introduction and training in flexible and rigid endoscopy have been identified. Discussion: The cross-institutional courses for physicians and technicians in the field of endo- and laparoscopy presented serve to provide a better understanding of the subject matter and the field of either discipline. Questions that arise in the field of endoscopy from physicians can be addressed at an early stage and, if necessary, worked on with little effort. Ideas for new instruments and even new interventions can arise and be pursued through an intensive exchange between technicians and physicians. Collaborations are established on a local basis which will foster national activities in this field and which allow to develop competencies relevant for the industrial sector of medical engineering.
Towards AI-driven minimally invasive needle interventions
Authors: Spiller Moritz , Esmaeili Nazila , Sühn Thomas , Boese Axel , Friebe Michael , Turial Salmai , Illanes Alfredo 
Published: September 2023

Abstract
The overall complication rate during laparoscopic access is estimated to be as high as 14 %. Surgeons have to rely heavily on their experience and haptic perception while inserting the Veress needle or a trocar into the peritoneal cavity. Surgical Audio Guidance (SURAG) is a promising alternative to current techniques. It acquires instrument-born vibroacoustic (VA) waves to track the insertion of the instrument and provide real-time feedback to surgeons. This article presents an initial evaluation of the SURAG technology through two sets of experiments to classify Veress needle events using different AI-models. The results demonstrate the feasibility of using AI for classifying Veress needle events and the potential of the SURAG technology to support surgeons during laparoscopic access and minimally invasive needle interventions in general.
PCB Coil Enables In Situ Calibration of Magnetoelectric Sensor Systems
Authors: Wolframm Henrik , Hoffmann Johannes , Burgardt Ralf , Elzenheimer Eric , Schmidt Gerhard , Höft Michael 
Published: September 2023

Abstract
Accurate calibration is key for any reliable sensor system. Magnetoelectric (ME) sensors, in particular, are influenced in their operating point by external parameters such as the Earth’s magnetic field or the ambient temperature. In this paper, we introduce a new planar coil design for the generation of a magnetic test field within the plane of the ME sensor. Furthermore, we implemented a method for measuring the sensor behaviour using a short-term magnetic noise signal. The combination of the printed circuit board (PCB) coil and the accelerated sensor characterization method allows the sensor system to be calibrated at the measurement site (in situ) without the need for laboratory equipment. We can show that the presented method for calibration achieves high-quality results in 10 seconds for a sensor affected by external interference fields.
Modified Allen Test Assessment via Imaging Photoplethysmography
Authors: Kossack Benjamin , Wisotzky Eric L. , Schraven Sebastian , Skopnik Lotte , Hilsmann Anna , Eisert Peter 
Published: September 2023

Abstract
The modified Allen test (MAT) is a widely used tool to examine the perfusion capacities of the arteries (ulnar or radial) of the hand. In clinical practice, MAT is utilized to ensure that in the event of occlusion, remaining vessels guarantee sufficient hand perfusion. This work shows that perfusion assessment via imaging photoplethysmography (iPPG) can be used to assess MAT. We captured the hands of seven subjects with a standard RGB camera while performing a MAT. Out of these captured video recordings, the iPPG signal was extracted via plane-orthogonal-to-skin transformation. Based on these extracted signals, we derive the heart rate, signal-to-noise ratio, DC parameter, and correlation with a reference iPPG signal to determine if an Allen test was pathological or inconspicuous. For all seven subjects, the results of our MAT assessment were identical to the medical expert’s assessment. This paper presents a procedure and initial thresholds for objectively evaluating and quantifying MAT.We show how globally and locally calculated parameters can be used to assess the perfusion of the investigated hand. This analysis makes it possible to quantify the exact point in time when the perfusion is again sufficient. If a reperfusion problem occurs, we are able to localize the spatial regions of occurrence. The presented hardware setup is affordable and can be easily installed and used in every doctor’s office.
Scalable mesh microelectrode arrays for neural spheroids and organoids
Authors: Stumpp Tom , Mierzejewski Michael , Pascual Domenic , Stumpf Angelika , Jones Peter D. 
Published: September 2023

Abstract
Introduction: Neural organoids promise to help understand the human brain and develop treatments for neurological diseases. Electrophysiological recordings are essential in neural models to evaluate the activity of neural circuits. Mesh microelectrode arrays (MEAs) have been demonstrated to be suitable for organoids and spheroids, and there is demand for easy-to-use devices that can be manufactured at scale. Methods: We present a new mesh MEA device with an easyto- use design. We produce mesh MEA chips on 100 mm carrier wafers and connect individual chips to PCBs by wirebonding. The devices are completed by assembly of a twopiece well and a glass cover slip. Results: Each device contains a suspended hammock-like mesh with 64 microelectrodes. The square grid’s pitch of 200 μm makes the mesh suitable for typical organoid sizes while spreading the electrodes across a 1.4 mm region. The well is designed for fluid handling by pipetting or pump systems. Impedance measurements indicate a high yield of functional microelectrodes, although further effort is needed to produce consistent low impedances. The devices are compatible with commercial amplifiers, while adaptation of the PCB to other formats will be straightforward. Conclusions: Using scalable production methods, we have developed a mesh MEA device design that offers improved ease-of-use. Next steps will include biological validation in collaboration with partners.
Using Hydrogel Beads as a Blood Model in Optical Coherence Tomography
Authors: Hentschel Gesine , Weiß Miriam , Hoffmann Simon , Nahm Werner , Glasmacher Birgit 
Published: September 2023

Abstract
Optical Coherence Tomography (OCT) is a standard imaging procedure in ophthalmology. OCT Angiography is a promising extension, allowing for fast and non-invasive imaging of the retinal vasculature analyzing multiple OCT scans at the same place. Local variance is examined and highlighted. Despite its introduction in the clinic, unanswered questions remain when it comes to signal generation. Multiphase fluids like intralipid, milk-water solutions and human blood cells were applied in phantom studies shedding light on some of the mechanisms. The use of hydrogel beads allows for the generation of alternative blood models for OCT and OCT Angiography. Beads were produced in Hannover, their size was measured and their long term stability was assessed. Then, beads were shipped to Karlsruhe, where OCT imaging resulted in first insights. The hydrogel acts as a diffusion barrier, which enables a clear distinction of bead and fluid when scattering particles were added. Further on, the scattering medium below the bead showed increased signal intensity. We conclude that the inside of the bead structure shows enhanced transmission compared to the plasma substitute with dissolved TiO2 surrounding it. Beads were found clumped and deformed after shipping, an issue to be addressed in further investigations. Nevertheless, hydrogel beads are promising as a blood model for OCT Angiography investigations, offering tunable optical parameters within the blood substitute solution.
Radial compliance of porcine Fallopian tubes ex vivo – perspectives for the development of a gynecological microstent
Authors: Siewert Stefan , Dierke Ariane , Stahnke Thomas , Großmann Swen , Brandt-Wunderlich Christoph , Supp Laura , Rosam Paula , Stiehm Michael , Bock Andrea , Zygmunt Marek , Schmitz Klaus-Peter 
Published: September 2023

Abstract
Fallopian tube occlusions represent one of the most common causes of female sterility. As an innovative treatment approach for affected persons, we previously presented the concept of a novel polymeric, self-expanding, and bioresorbable microstent. As a basis for microstent development, knowledge of the mechanical properties of the anatomical target structure represents a crucial requirement. The current work describes a methodological approach for the experimental determination of radial Fallopian tube compliance using optical coherence tomography. It could be shown that a quantitative assessment of the mechanical properties of porcine Fallopian tube samples - as a whole anatomical structure including the Tunica mucosa, the Tunica muscularis, and the Tunica serosa - is possible, using the described test setup. Future investigations on human samples will allow for valuable information regarding the structural-mechanical properties of the Fallopian tube. Therefore, the current work offers perspectives for the development of a novel gynecological microstent for the treatment of Fallopian tube occlusions.
A comparison of two CNN-based instrument detection approaches for automated surgical assistance systems
Authors: Bajraktari Flakë , Fleissner Kathrin , Pott Peter P. 
Published: September 2023

Abstract
The shortage of operating room technicians has led to a growing demand for automated systems in the OR to maintain the quality of care. Robotic scrub nurse (RSN) systems are increasingly being developed, which perform tasks such as handling instruments and documenting the surgery. While research has focused on detecting instruments in the hands of surgical staff or recognizing surgical phases, there is a lack of research on detecting instruments on the instrument tray. Therefore, this study proposes and evaluates two distinct methodologies for instrument detection on the OR table using the deep learning approaches YOLOv5 and Mask R-CNN. The performance of the two approaches has been evaluated on 18 YOLOv5 models and twelve Mask R-CNN models, mainly differing in model size. Two sets of instruments were used to assess generalizability of the models. The results show a mean average precision (mAP) score of 0.978 for YOLOv5 and 0.846 for Mask R-CNN on the test dataset comprising three classes. An mAP of 0.874 and 0.707 have been computed respectively for the test dataset including six classes. The study provides a comparison of the performance of two suitable approaches for instrument detection on the instrument tray in the OR to enhance the development of RSN systems.