Klaus D Tönnies

Klaus D Tönnies
Otto-von-Guericke-Universität Magdeburg | OvGU · Department of Simulation and Graphics (ISG)

About

257
Publications
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1,956
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Publications

Publications (257)
Article
Full-text available
Purpose Development and performance measurement of a fully automated pipeline that localizes and segments the locus coeruleus in so-called neuromelanin-sensitive magnetic resonance imaging data for the derivation of quantitative biomarkers of neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease. Methods We propose a pipel...
Preprint
Full-text available
Recent studies demonstrated the eligibility of convolutional neural networks (CNNs) for solving the image registration problem. CNNs enable faster transformation estimation and greater generalization capability needed for better support during medical interventions. Conventional fully-supervised training requires a lot of high-quality ground truth...
Preprint
Full-text available
This study's objective was to segment spinal metastases in diagnostic MR images using a deep learning-based approach. Segmentation of such lesions can present a pivotal step towards enhanced therapy planning and validation, as well as intervention support during minimally invasive and image-guided surgeries like radiofrequency ablations. For this p...
Conference Paper
Full-text available
Virtual borders are an opportunity to allow users the interactive restriction of their mobile robots' workspaces, e.g. to avoid navigation errors or to exclude certain areas from working. Currently, works in this field have focused on human-robot interaction (HRI) methods to restrict the workspace. However, recent trends towards smart environments...
Article
Full-text available
Virtual borders are employed to allow humans the interactive and flexible restriction of their mobile robots' workspaces in human-centered environments, e.g. to exclude privacy zones from the workspace or to indicate certain areas for working. They have been successfully specified in interaction processes using methods from human-robot interaction....
Chapter
The extraction of spines from medical records in a fast yet accurate way is a challenging task, especially for large data sets. Addressing this issue, we present a framework based on convolutional neural networks for the reconstruction of the spinal shape and curvature, making statistical assessments feasible on epidemiological scale. Our method us...
Preprint
Full-text available
The extraction of spines from medical records in a fast yet accurate way is a challenging task, especially for large data sets. Addressing this issue, we present a framework based on convolutional neural networks for the reconstruction of the spinal shape and curvature, making statistical assessments feasible on epidemiological scale. Our method us...
Article
Full-text available
Human-aware robot navigation is an essential aspect to increase the acceptance of mobile service robots in human-centered environments, e.g. home environments. Robots need to navigate in a human-acceptable way according to the users’ conventions, presence and needs. In order to address the users’ needs, we employ virtual borders, which are non-phys...
Chapter
Monitoring public space with imaging sensors to perform an object- or person-tracking is often associated with privacy concerns. We present a Dynamic Vision Sensor (DVS) based approach to achieve this tracking that does not require the creation of conventional grey- or color images. These Dynamic Vision Sensors produce an event-stream of informatio...
Article
Background and objective: We propose an automatic approach for fast vertebral body segmentation in three-dimensional magnetic resonance images of the whole spine. Previous works are limited to the lower thoracolumbar section and often take minutes to compute, which is problematic in clinical routine, for study data sets with numerous subjects or w...
Preprint
Full-text available
Virtual borders are employed to allow humans the interactive and flexible restriction of their mobile robots' workspaces in human-centered environments, e.g. to exclude privacy zones from the workspace or to indicate certain areas for working. They have been successfully specified in interaction processes using methods from human-robot interaction....
Conference Paper
Full-text available
We address the problem of controlling the workspace of a 3-DoF mobile robot. In a human-robot shared space, robots should navigate in a human-acceptable way according to the users' demands. For this purpose, we employ virtual borders, that are non-physical borders, to allow a user the restriction of the robot's workspace. To this end, we propose an...
Conference Paper
Full-text available
We address the problem of interactively controlling the workspace of a mobile robot to ensure a human-aware navigation. This is especially of relevance for non-expert users living in human-robot shared spaces, e.g. home environments, since they want to keep the control of their mobile robots, such as vacuum cleaning or companion robots. Therefore,...
Article
Background: Radiofrequency ablation was introduced recently to treat spinal metastases, which are among the most common metastases. These minimally-invasive interventions are most often image-guided by flat-panel CT scans, withholding soft tissue contrast like MR imaging. Image fusion of diagnostic MR and operative CT images could provide importan...
Article
Liver segmentation and volumetry in native MR-volume data is an important topic in epidemiological research. Manual liver segmentation is extremely time-consuming and often infeasible requiring automatized methods. Automatic liver segmentation is challenging because of the large variability in liver shape and appearance and the low contrast to neig...
Article
Background and objective: In this work we propose a 3D vertebral body segmentation approach for clinical magnetic resonance (MR) spine imaging. So far, vertebrae segmentation approaches in MR spine imaging are either limited to particular MR imaging sequences or require minutes to compute, which can be hindering in clinical routine. The major cont...
Article
Objectives We aimed to develop the first fully automated 3D gallbladder segmentation approach to perform volumetric analysis in volume data of magnetic resonance (MR) cholangiopancreatography (MRCP) sequences. Volumetric gallbladder analysis is performed for non-contrast-enhanced and secretin-enhanced MRCP sequences. Materials and methodsNative and...
Conference Paper
Full-text available
In interstitial HDR brachytherapy, liver cancer is treated by internal radiation, requiring percutaneous placement of applicators within the tumor guided by interventional MRI. A mapping of pre-planning information onto interventional data would reduce the radiologist's cognitive load during the intervention. We performed a comprehensive investigat...
Preprint
Full-text available
We address the problem of interactively controlling the workspace of a mobile robot to ensure a human-aware navigation. This is especially of relevance for non-expert users living in human-robot shared spaces, e.g. home environments, since they want to keep the control of their mobile robots, such as vacuum cleaning or companion robots. Therefore,...
Preprint
Full-text available
In this paper, we address the problem of controlling the workspace of a 3-DoF mobile robot. This problem arises due to the emerging coexistence between humans and robots resulting in a shared space. In such an environment, robots should navigate in a human-acceptable way according to the users' demands. For this purpose, we propose a method that gi...
Conference Paper
Full-text available
The increasing number of robots in home environments leads to an emerging coexistence between humans and robots. Robots undertake common tasks and support the residents in their everyday life. People appreciate the presence of robots in their environment as long as they keep the control over them. One important aspect is the control of a robot's wo...
Article
Purpose: In interstitial high-dose rate brachytherapy, liver cancer is treated by internal radiation, requiring percutaneous placement of applicators within or close to the tumor. To maximize utility, the optimal applicator configuration is pre-planned on magnetic resonance images. The pre-planned configuration is then implemented via a magnetic r...
Article
Object: To develop the first fully automated 3D spleen segmentation framework derived from T1-weighted magnetic resonance (MR) imaging data; and to verify its performance for spleen delineation and volumetry. This approach considers the issue of low contrast between spleen and adjacent tissue in non-contrast-enhanced MR images. Materials and Meth...
Chapter
Active contours and active surfaces are means of model-driven segmentation. Their use enforces closed and smooth boundaries for each segmentation irrespective of the image content. They are particularly useful if such properties cannot be derived everywhere from the data. We will discuss explicit and implicit active contours, their definition, para...
Chapter
Object detection in medical image analysis can be modelled as a search for an object model in the image. The model describes attributes such as shape and appearance of the object. The search consists of fitting instances of the model to the data. A quality-of-fit measure determines whether one or several objects have been found. Generating the mode...
Chapter
Two reasons exist for applying an image enhancement technique. Enhancement can increase perceptibility of objects in an image to the human observer or it may be needed as a preprocessing step for subsequent automatic image analysis. Enhancement methods differ for the two purposes. An enhancement method requires a criterion by which its success can...
Chapter
The purpose of image segmentation is to generate pixel agglomerations from an image that constitute parts of depicted objects. In medical imaging, segmentation often refers to the delineation of specific structures. Hence, it includes parts of classification as well. Segmentation strategies in medical imaging combine data knowledge with domain know...
Chapter
Image-based features such as key point locations or potential parts of object boundaries can be extracted from local image characteristics. Boundary parts are generated from results of an edge-enhancement step, while key point locations are local extrema of some local object property. Features may also be computed from samples of an object’s bounda...
Chapter
Selection of an image acquisition technique is intentional in medical imaging. It can be assumed that pixel or voxel values in a medical image cover more semantics with respect to object class membership than intensity in a photograph. Hence, image segmentation can be done as classification in feature space where image intensities are the features....
Chapter
2d and 3d images can be mapped on a graph where scene elements are nodes and neighborhood is expressed by edges connecting the nodes. Assigning weights to edges that represent local properties of a good segmentation allows finding a segmentation using optimization methods on graphs. Two such techniques that have been used for segmentation are minim...
Chapter
Assigning semantics to segments is required if segmentation has not been combined with object detection. Classification is then based on evaluating segment attributes such as shape and appearance. The dimension of feature space is often high (>10) and the number of samples to train a classifier or to deduce a clustering is low. Methods are differen...
Chapter
Information about an object from different sources can be combined if a transformation allows mapping data from one source to data of the other source. In medical imaging, the two sources are image acquisition systems. If the two sources depict the same subject, this process is called registration. If they depict different subjects, it is called no...
Chapter
Medical images are pictures of distributions of physical attributes captured by an image acquisition system. Most of today’s images are digital. They may be post-processed for analysis by a computer-assisted method. Medical images come in one of two varieties: Projection images project a physical parameter in the human body on a 2d image, while sli...
Chapter
Medical images are created, stored, accessed, and processed in the restricted environment of a hospital. The semantic of a medical image is driven by the particular purpose for creating it. This results in specific solutions for the archival of medical images. Transfer is different for medical images as well as driven by the technical specification...
Chapter
Medical images are different from other pictures in that they depict distributions of various physical features measured from the human body. They show attributes that are otherwise inaccessible. Furthermore, analysis of such images is guided by very specific expectations which gave rise to acquiring the images in the first place. This has conseque...
Chapter
Structures to be analyzed in medical images are usually inaccessible. Sufficiency and correctness of employed domain knowledge cannot be proven. Hence, validation of an analysis method estimates correctness of results from tests on a limited number of samples. For carrying out the validation, suitable samples need to be selected, comparison measure...
Chapter
We propose a semi-automatic approach for aorta centerline extraction in contrast-enhanced MRI, making aorta length analysis feasible on large scale. Starting from user-specified start and end regions, we extract the aorta path in between the regions automatically. The extraction is formulated as an optimization problem, seeking for the path that mo...
Chapter
Every surgical intervention results in physical injuries. Therefore, the patient’s consent is required to avoid liability in case of bodily harm. In a lot of countries a stepwise clarification process is common, combining written and verbal clarification, the latter in form of a conversation between patient and surgeon. However, many studies have s...
Book
This comprehensive guide provides a uniquely practical, application-focused introduction to medical image analysis. The text presents a concise examination of each of the key concepts, enabling the reader to understand the interdependencies between them before delving deeper into the derivations and technical details. This fully updated new edition...
Article
Full-text available
In clinical routine, spine pathologies can be most often deduced from the vertebral body shape, position and orientation. Additionally, per-vertebra spatial information could be used in intervention planning and surgical navigation. Especially in vertebral metastasis treatment, MRI is inalienable, and therefore, segmentation methods are developed f...
Conference Paper
Full-text available
In recent years, analysis of magnetic resonance images of the spine gained considerable interest with vertebra localization being a key step for higher level analysis. Approaches based on trained appearance - which are de facto standard - may be inappropriate for certain tasks, because processing usually takes several minutes or training data is un...
Article
Contextual cueing leads to faster search times in repeated displays. The global layout of a search display facilitates search in repeated displays (Brady & Chun, 2007). However, peripheral vision can only convey a limited amount of information about the environment. We used a model of visual summary statistics (Portilla & Simoncelli, 2000; Balas 20...
Article
Purpose: In the last decades, the increasing medical interest in magnetic resonance imaging (MRI) of the spine gave rise to a growing number of publications on computerized methods for spine analysis, covering goals such as localization and segmentation of vertebrae and intervertebral discs as well as the extraction and segmentation of the spinal...
Chapter
Epidemiology characterizes the influence of causes to disease and health conditions of defined populations. Cohort studies are population-based studies involving usually large numbers of randomly selected individuals and comprising numerous attributes, ranging from self-reported interview data to results from various medical examinations, e.g., blo...
Article
Full-text available
In epidemiological studies as well as in clinical practice the amount of produced medical image data strongly increased in the last decade. In this context organ segmentation in MR volume data gained increasing attention for medical applications. Especially in large-scale population-based studies organ volumetry is highly relevant requiring exact o...
Article
Observation of molecular dynamics is often biased by the optical very heterogeneous environment of cells and complex tissue. Here, we have designed an algorithm that facilitates molecular dynamic analyses within brain slices. We adjust fast astigmatism-based three-dimensional single-particle tracking techniques to depth-dependent optical aberration...
Conference Paper
Full-text available
The centerline of the spinal canal holds interesting information which can be used for tasks such as segmenting the spinal canal or to track the progression of spinal defor- mities. We propose a method that extracts the centerline of the canal by a shortest path search in 4D, whereby dimensions correspond to 3D canal location and canal width. Our m...
Article
We propose a novel method capable of detecting and segmenting quasi-planar surfaces based on homograph decomposition and Semi-Global-Matching without the need for extrinsic calibration or stereo rectification. Existing methods require co planarity of all points on the dominant plane and are thus unsuited for unconstrained quasi-planar surfaces. In...
Article
We present a novel method for photogrammetric wood pile surveying, which runs on mobile devices as well as on desktop computers. The demand for measurement techniques for wood piles has strongly increased in the last years. Unlike existing methods, our method is not limited to a single image and uses 3D reconstruction techniques on a set of images...
Article
Organ segmentation in MR volume data is of increasing interest in epidemiological studies and clinical practice. Especially in large-scale population-based studies organ volumetry is highly relevant requiring exact organ segmentation. Since manual segmentation is time-consuming and prone to reader variability, large-scale studies need automatic met...
Article
A rising number of epidemiological studies apply imaging technologies. Images are not features themselves but provide raw data from which features are extracted. Different to other applications of analysis of medical images the data is analyzed statistically across the cohort. It results in unique requirements regarding the development of methods t...
Article
Full-text available
Epidemiology characterizes the influence of causes to disease and health conditions of defined populations. Cohort studies are population-based studies involving usually large numbers of randomly selected individuals and comprising numerous attributes, ranging from self-reported interview data to results from various medical examinations, e.g., blo...
Article
Full-text available
Identifying differences among the sample distributions of different observations is an important issue in many fields ranging from medicine over biology and chemistry to physics. We address this issue, providing a general framework to detect difference spots of interest in feature space. Such spots occur not only at various locations, they may also...
Article
The amount of engineered nanoparticles produced each year has grown for some time and will grow in the coming years. However, if such particles are inhaled, they can be toxic. Therefore, to ensure the safety of workers, the nanoparticle concentrations at workplaces have to be measured. This is usually done by gathering the particles in the ambient...
Conference Paper
Identifying differences among the distribution of samples of different observations is an important issue in many research fields. We provide a general framework to detect these difference spots in d-dimensional feature space. Such spots occur not only at various locations , they may also come in various shapes and multiple sizes, even at the same...
Chapter
We address the task of aortic diameter measurement in (noncontrast- enhanced) plain axial cardiac cine MRI. To this end, we set up a likelihood maximization problem which allows us to recover globally optimal aorta locations and diameters of the cine sequence efficiently. Our approach provides intuitive means of manual post-correction and requires...
Chapter
Epidemiology studies on vertebra’s shape and appearance require big databases of medical images and image processing methods, that are robust against deformation and noise. This work presents a solution of the first step: the vertebrae detection. We propose a method that automatically detects the central spinal curve with 3D data-driven methods in...
Article
Full-text available
Purpose: Diagnosis of neuromuscular diseases in ultrasonography is a challenging task since experts are often unable to discriminate between healthy and pathological cases. A computer-aided diagnosis (CAD) system for skeletal muscle ultrasonography was developed and tested for myositis detection in ultrasound images of biceps brachii. Methods: S...
Conference Paper
Full-text available
There have recently been advances in the area of fully automatic detection of clustered objects in color images. State of the art methods combine detection with segmentation. In this paper we show that these methods can be significantly improved by introducing a new iterative classification, statistical modeling, and segmentation procedure. The pro...
Conference Paper
It is desirable to predict the influence of additional training data on classification performance because the generation of samples is often costly. Current methods can only predict performance as measured by accuracy, which is not suitable if one class is much rarer than another. We propose an approach which is able to also predict other measures...