Tobias Heimann

Tobias Heimann
Siemens Healthineers · Medical Imaging Technologies

Dr. rer. nat.

About

86
Publications
13,910
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
3,929
Citations

Publications

Publications (86)
Conference Paper
In this paper, we propose an innovative approach for registration based on the deterministic prediction of the parameters from both images instead of the optimization of a energy criteria. The method relies on a fully convolutional network whose architecture consists of contracting layers to detect relevant features and a symmetric expanding path t...
Conference Paper
Full-text available
Personalised 3D modelling of the heart is of increasing interest in order to better characterise pathologies and predict evolution. The personalisation consists in estimating the parameter values of an electromechanical model in order to reproduce the observed cardiac motion. However, the number of parameters in these models can be high and their e...
Conference Paper
Computer models of the heart are of increasing interest for clinical applications due to their discriminative and predictive abilities. However the number of simulation parameters in these models can be high and expert knowledge is required to properly design studies involving these models, and analyse the results. In particular it is important to...
Conference Paper
Transesophageal Echocardiography (TEE) and X-Ray fluoroscopy are two routinely used real-time image guidance modalities for interventional procedures, and co-registering them into the same coordinate system enables advanced hybrid image guidance by providing augmented and complimentary information. In this paper, we present an image-based system of...
Article
Purpose: Coarctation of the aorta (CoA) is a congenital heart disease characterized by an abnormal narrowing of the proximal descending aorta. Severity of this pathology is quantified by the blood pressure drop (△P) across the stenotic coarctation lesion. In order to evaluate the physiological significance of the preoperative coarctation and to as...
Conference Paper
Full-text available
2D/3D registration is a well known technique in medical imaging for combining pre-operative volume data with live fluoroscopy. A common issue of this type of algorithms is that out-of-plane parameters are hard to determine. One solution to overcome this issue is the use of X-ray images from two angulations. However, performing in-plane transformati...
Conference Paper
Hybrid imaging systems, consisting of fluoroscopy and echocardiography, are increasingly selected for intra-operative support of minimally invasive cardiac interventions. Intracardiac echocardiograpy (ICE) is an emerging modality with the promise of removing sedation or general anesthesia associated with transesophageal echocardiography (TEE). We i...
Article
The fusion of image data from trans-esophageal echography (TEE) and X-ray fluoroscopy is attracting increasing interest in minimally-invasive treatment of structural heart disease. In order to calculate the needed transformation between both imaging systems, we employ a discriminative learning (DL) based approach to localize the TEE transducer in X...
Conference Paper
Full-text available
For instrument guidance in X-ray-based interventional procedures, 2D/3D registration is an important method to fuse pre-op 3D images with live X-ray images. The user modifies the six degrees of freedom (DOF) of the 3D image and thereby aligns a projection of it to the given X-ray images. Because of the projective geometry of X-ray, the classic hand...
Conference Paper
Full-text available
Ultrasound and X-ray are two facilitating imaging modalities in the field of transcatheter-based minimally invasive procedures in structural heart disease. X-ray fluoroscopy provides excellent instrument imaging and ultrasound shows high-quality images of soft tissue. A fusion of both modalities can potentially improve the surgical workflow and the...
Conference Paper
The fusion of image data from trans-esophageal echography (TEE) and X-ray fluoroscopy is attracting increasing interest in minimally-invasive treatment of structural heart disease. In order to calculate the needed transform between both imaging systems, we employ a discriminative learning based approach to localize the TEE transducer in X-ray image...
Article
To validate Fourier decomposition (FD) magnetic resonance (MR) imaging in cystic fibrosis (CF) patients with dynamic contrast-enhanced (DCE) MR imaging. Thirty-four CF patients (median age 4.08 years; range 0.16-30) were examined on a 1.5-T MR imager. For FD MR imaging, sets of lung images were acquired using an untriggered two-dimensional balanced...
Article
We propose a top-down fully automatic 3D vertebra segmentation algorithm using global shape-related as well as local appearance-related prior information. The former is brought into the system by a global statistical shape model built from annotated training data, i.e., annotated CT volumes. The latter is handled by a machine learning-based compone...
Article
Purpose: To develop an automated method with which to distinguish metabolically different adipose tissues in a large number of subjects using whole-body magnetic resonance imaging (MRI) datasets for improving the understanding of chronic disease risk predictions associated with distinct adipose tissue compartments. Materials and methods: In all,...
Article
Full-text available
The segmentation of tree-like tubular structures such as coronary arteries and airways is an essential step for many 3D medical imaging applications. Statistical tracking techniques for the extraction of elongated structures have received considerable attention in recent years due to their robustness against image noise and pathological changes. Ho...
Chapter
In dieser Arbeit wird ein Verfahren zur effizienten und interaktiven Erstellung einer 3D Segmentierung vorgestellt. Dafür wird die Oberfläche des zu segmentierenden Bereiches auf Basis manuell gezeichneter Konturen mittels radialer Basisfunktionen interpoliert. Um die Auswirkung zusätzlicher Konturen auf die interpolierten Oberfläche in wenigen Sek...
Chapter
Mitralklappeninsuffizienz (MI) ist eine weit verbreitete Erkrankung. Für eine erfolgreiche und nachhaltige chirurgische Therapie ist die Ausmessung des Mitralannulus (MA) notwendig. Wir stellen eine Methode zur automatischen Bestimmung des MA Durchmessers auf Basis von Live-3D Ultraschall Daten vor, die zusätzlich für jeden Zeitschritt den Herzzykl...
Conference Paper
Range imaging modalities, such as time-of-flight cameras (ToF), are becoming very popular for the acquisition of intra-operative data, which can be used for registering the patient's anatomy with pre-operative data, such as 3D images generated by computed tomographies (CT) or magnetic resonance imaging (MRI). However, due to the distortions that ap...
Article
Mitral regurgitation is a wide spread problem. For successful surgical treatment quantification of the mitral annulus, especially its diameter, is essential. Time resolved 3D transesophageal echocardiography (TEE) is suitable for this task. Yet, manual measurement in four dimensions is extremely time consuming, which confirms the need for automatic...
Article
The ratio between the amount of adipose and skeletal muscle tissue is an important determinant of metabolic health. Recent developments in MRI technology allow whole body scans to be performed for accurate assessment of body composition. In the present study, a total of 194 participants underwent a 2-point Dixon MRI sequence of the whole body. A fu...
Article
Full-text available
MRI perfusion images give information about regional lung function and can be used to detect pulmonary pathologies in cystic fibrosis (CF) children. However, manual assessment of the percentage of pathologic tissue in defined lung subvolumes features large inter- and intra-observer variation, making it difficult to determine disease progression con...
Article
Full-text available
Congenital heart defect (CHD) corrective interventions in infants are extremely challenging due to commonly complex and heterogeneous disease pat-terns. At present, cardiac surgeons can only rely on non-invasive imaging prior to surgery. Critical decisions regarding the surgical procedure of choice and its exe-cution must be made during the actual...
Conference Paper
Time-of-flight (ToF) cameras are a novel, fast, and robust means for intra-operative 3D surface acquisition. They acquire surface information (range images) in real-time. In the intra-operative registration context, these surfaces must be matched to pre-operative CT or MR surfaces, using so called descriptors, which represent surface characteristic...
Article
Vessel tree tracking is an important and challenging task for many medical applications. This paper presents a novel bifurcation detection algorithm for Bayesian tracking of vessel trees. Based on a cylindrical model, we introduce a bifurcation metric that yields minimal values at potential branching points. This approach avoids searching for bifur...
Article
Obesity is an increasing problem in the western world and triggers diseases like cancer, type two diabetes, and cardiovascular diseases. In recent years, magnetic resonance imaging (MRI) has become a clinically viable method to measure the amount and distribution of adipose tissue (AT) in the body. However, analysis of MRI images by manual segmenta...
Conference Paper
Full-text available
Das Verfolgen von tubulären Strukturen aus 3D medizinischen Bilddaten ist essentiell für viele computergestützte medizinische Anwendungen. In diesem Beitrag wird ein Algorithmus zur automatischen Detektion der Verzweigungen für das statistische Tracking der Koronararterien vorgestellt. Basierend auf einem zylindrischen Modell wird ein Maß für die E...
Conference Paper
Full-text available
Fettleibigkeit ist ein verbreitetes Problem in der westlichen Welt und kann Krankheiten wie Krebs, Typ-2-Diabetes und Herz- Kreislauf-Erkrankungen auslösen. In den vergangenen Jahren wurde die Magnetresonanztomographie (MRT) zu einer praktikablen Methode, um die Menge und Verteilung des Fettgewebes im Körper zu messen. Die manuelle Analyse ist beso...
Chapter
This chapter starts with a brief introduction into model-based segmentation, explaining the basic concepts and different approaches. Subsequently, two segmentation approaches are presented in more detail: First, the method of deformable simplex meshes is described, explaining the special properties of the simplex mesh and the formulation of the int...
Article
Understanding and modeling liver biomechanics represents a significant challenge due to its complex nature. In this paper, we tackle this issue in the context of real-time surgery simulation where a compromise between biomechanical accuracy and computational efficiency must be found. We describe a realistic liver model including hyperelasticity, po...
Conference Paper
Full-text available
Simulating soft tissues in real time is a significant challenge since a compromise between biomechanical accuracy and computational efficiency must be found. In this paper, we propose a new discretization method, the Multiplicative Jacobian Energy Decomposition (MJED) which is an alternative to the classical Galerkin FEM (Finite Element Method) for...
Article
Due to noise and artifacts often encountered in medical images, segmenting objects in these is one of the most challenging tasks in medical image analysis. Model-based approaches like statistical shape models (SSMs) incorporate prior knowledge that supports object detection in case of in-complete evidence from image data. In this paper, we present...
Chapter
Full-text available
We present an efficient finite element method to simulate a transversely isotropic nonlinear material for ligaments. The approach relies on tetrahedral elements and exploits the geometry to optimize computation of the derivatives of the strain energy. To better support incompressibility, deviatoric and dilational responses are uncoupled and a penal...
Article
Full-text available
In this paper, we present an evaluation framework for the 3D segmentation of knee bones and cartilage from magnetic resonance im-ages. The framework was established for one of the three challenges at the "Medical Image Analysis for the Clinic: A Grand Challenge" workshop held at the 2010 Medical Image Computing and Computer Assisted Inter-vention (...
Conference Paper
Full-text available
Simulating soft tissues in real time is a significant challenge since a compromise between biomechanical accuracy and computational efficiency must be found. In this paper, we propose a new discretiza-tion method, the Multiplicative Jacobian Energy Decomposition (MJED) which is an alternative to the classical Galerkin FEM (Finite Element Method) fo...
Article
This paper presents a comparison study between 10 automatic and six interactive methods for liver segmentation from contrast-enhanced CT images. It is based on results from the "MICCAI 2007 Grand Challenge" workshop, where 16 teams evaluated their algorithms on a common database. A collection of 20 clinical images with reference segmentations was p...
Article
Statistical shape models (SSMs) have by now been firmly established as a robust tool for segmentation of medical images. While 2D models have been in use since the early 1990 s, wide-spread utilization of three-dimensional models appeared only in recent years, primarily made possible by breakthroughs in automatic detection of shape correspondences....
Article
Full-text available
The random walker algorithm is a graph-based segmentation method that has become popular over the past few years. The basis of the algorithm is a large, sparsely occupied system of linear equations, whose size corresponds to the number of voxels in the image. To solve these systems, typically comprised of millions of equations, the computational pe...
Conference Paper
Full-text available
Segmentierung mit Hilfe von deformierbaren modellbasierten Ansätzen hat sich zu einer gängigen Praxis in der medizinischen Bildanalyse entwickelt, da sie eine schnelle und robust Methode zur semioder vollautomatischen Detektion von Strukturen darstellt, also z.B. Organen. In diesem Paper wird die Anwendung eines deformierbaren Formmodells zur funkt...
Conference Paper
Full-text available
Establishing optimal correspondence across object populations is essential to statistical shape analysis. Minimizing the description length (MDL) is a popular method for finding correspondence. In this work, we extend the MDL method by incorporating various local curvature metrics. Using local curvature can improve performance by ensuring that corr...
Article
Full-text available
Objective quantification of disease specific neurodegenerative changes can facilitate diagnosis and therapeutic monitoring in several neuropsychiatric disorders. Reproducibility and easy-to-perform assessment are essential to ensure applicability in clinical environments. Aim of this comparative study is the evaluation of a fully automated approach...
Article
Full-text available
With many tumor entities, quantitative assessment of lymph node growth over time is important to make therapy choices or to evaluate new therapies. The clinical standard is to document diameters on transversal slices, which is not the best measure for a volume. We present a new algorithm to segment (metastatic) lymph nodes and evaluate the algorith...
Article
Due to the high noise and artifacts typically encountered in ultrasound images, segmenting objects from this modality is one of the most challenging tasks in medical image analysis. Model-based approaches like statistical shape models (SSMs) incorporate prior knowledge that supports object detection in case of incomplete evidence from the image dat...
Conference Paper
Statistical shape models have become a fast and robust method for segmentation of anatomical structures in medical image volumes. In clinical practice, however, pathological cases and image artifacts can lead to local deviations of the detected contour from the true object boundary. These deviations have to be corrected manually. We present an intu...
Conference Paper
Full-text available
Kurzfassung. Bereichswachstumsverfahren weisen bei der Segmentie- rung von tubularen Strukturen geringe Laufzeiten auf, bergen aber die Gefahr von ¨ Ubersegmentierungen in Form von Auslaufen in benachbarte Strukturen in sich. Modellbasierte Verfahren liefern hier robustere Ergeb- nisse, sind jedoch deutlich rechenintensiver. Dieser Beitrag beschrei...
Conference Paper
Full-text available
Diese Arbeit beschreibt ein modellbasiertes Verfahren zur Segmentierung der Prostata aus 3D-Ultraschalldaten. Kern der Methode ist ein statistisches Formmodell, das auf Beispieldaten der Prostata trainiert wird. Erster Schritt der Segmentierung ist ein evolutionärer Algorithmus, mit dem das Modell grob im zu segmentierenden Bild positioniert wird....
Conference Paper
Neue Bildverarbeitungsmethoden werden häufig hauptsächlich für Publikationszwecke entwickelt. DieWeiterentwicklung bis zur Verwendbarkeit für klinische Anwender erfordert zusätzlichen Aufwand und wird daher oft nicht weiter verfolgt. In dieser Arbeit wurden mehrere Bildanalyseverfahren unserer Abteilung konsequent zu einem stabilen und benutzbaren...
Conference Paper
Full-text available
Segmentation using deformable model-based approaches has become a common application in 3D medical image analysis, as it provides a fast and robust method to detect structures, e.g. organs, fully-automated after initialization. However, some earlier approaches in some cases did not converge in the segmentation process even on rather good datasets o...
Conference Paper
Full-text available
We present a novel method for the segmentation of volumetric images, which is especially suitable for highly variable soft tissue structures. Core of the algorithm is a statistical shape model (SSM) of the structure of interest. A global search with an evolutionary algorithm is employed to detect suitable initial parameters for the model, which are...
Article
To point out the problem of non-uniform landmark placement in statistical shape modeling, to present an improved method for generating landmarks in the 3D case and to propose an unbiased evaluation metric to determine model quality. Our approach minimizes a cost function based on the minimum description length (MDL) of the shape model to optimize l...
Conference Paper
Full-text available
Wir stellen eine neuartige Methode zur Segmentierung volumetrischer Bilddaten vor, die Techniken von statistischen Formmodellen mit deformierbaren Oberflächen kombiniert. Die internen Kräfte der deformierbaren Oberfläche berechnen sich dabei aus einem mitlaufenden Formmodell, während die externen Kräfte aus einem graph-basierten Verfahren zur optim...
Conference Paper
Full-text available
Statistische Formmodelle sind eine populäre Methode um den Segmentierungsprozess in der medizinischen Bildverarbeitung zu automatisieren. Dafür ist es notwendig, zuerst korrespondierende Landmarken auf den Oberflächen von Trainingsformen zu finden. Ein erfolgversprechender automatischer Ansatz hierzu [1] basiert auf Parametrisierungen: Dabei werden...
Conference Paper
Full-text available
Zur Segmentierung mit Formmodellen werden Erscheinungsmodelle benötigt, die eine exakte Anpassung an die Bilddaten ermöglichen. Wir haben Standardverfahren und nichtlineare Modellierungsmethoden für die 3D-Segmentierung erweitert und auf klinischen Leberdaten evaluiert. Mit nichtlinearen Erscheinungsmodellen wurden insgesamt deutlich bessere Ergebn...
Article
Full-text available
We present a fully automated method based on an evolu-tionary algorithm, a statistical shape model (SSM), and a deformable mesh to tackle the liver segmentation task of the MICCAI Grand Chal-lenge workshop. To model the expected shape and appearance, the SSM is trained on the 20 provided training datasets. Segmentation is started by a global search...
Article
Full right hepatic grafts are most frequently used for adult-to-adult living donor liver transplantation (LDLT). One of the major problems is venous drainage of segments 5 and 8. Thus, this study was designed to provide information on venous drainage of right liver lobes for operation-planning. Fifty-six CT data sets from routine clinical imaging w...
Article
Full-text available
Minimizing the description length (MDL) is one of the most promising methods to automatically generate 3D statistical shape models. By modifying an initial landmark distribution according to the MDL cost function, points across the different training shapes are brought into correspondence. A drawback of the current approach is that the user has no...
Conference Paper
Full-text available
This paper presents an evaluation of the performance of a three-dimensional Active Shape Model (ASM) to segment the liver in 48 clinical CT scans. The employed shape model is built from 32 samples using an optimization approach based on the minimum description length (MDL). Three different gray-value appearance models (plain intensity, gradient and...
Conference Paper
Die Minimierung der Beschreibungslänge (MDL) ist eine der vielversprechendsten Methoden, um automatisch die nötigen Punkt-Korrespondenzen für die Erstellung statistischer Formmodelle zu bestimmen. Bisher gibt es allerdings keine Möglichkeit, die Verteilung der erstellten Landmarken auf dem Modell zu beeinflussen, was zu unzureichenden Formdarstellu...