Dr. Jan Ehrhardt Profile

Dr. Jan Ehrhardt

Scientific Researcher at University of Lübeck

SPIE Involvement:

Conference Program Committee | Author

Publications (32)

Proceedings Article | 3 April 2024 Poster + Paper

Focused unsupervised image registration for structure-specific population analysis

Jan Ehrhardt, Hristina Uzunova, Paul Kaftan, Julia Krüger, Roland Opfer, Heinz Handels

Proceedings Volume 12927, 129272F (2024) https://doi.org/10.1117/12.3006119

KEYWORDS: Image registration, Image segmentation, Deformation, Image resolution, Image processing, Neuroimaging, Brain, Alzheimer disease

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Proceedings Article | 3 April 2024 Presentation + Paper

Comparison of anatomical priors for learning-based neural network guidance for mediastinal lymph node segmentation

Sofija Engelson, Jan Ehrhardt, Timo Kepp, Joshua Niemeijer, Stefanie Schierholz, Lennart Berkel, Yannic Elser, Malte Maria Sieren, Heinz Handels

Proceedings Volume 12927, 129271K (2024) https://doi.org/10.1117/12.3006158

KEYWORDS: Lymph nodes, Education and training, Anatomy, Image segmentation, Computed tomography, Neural networks, Image registration, Tumor growth modeling, Tumors, Lung

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Proceedings Article | 7 April 2023 Presentation + Paper

Overcoming the sensor delta for semantic segmentation in OCT images

Joshua Niemeijer, Jan Ehrhardt, Timo Kepp, Jörg Schäfer, Heinz Handels

Proceedings Volume 12465, 1246511 (2023) https://doi.org/10.1117/12.2654187

KEYWORDS: Education and training, Image segmentation, Sensors, Optical coherence tomography, Semantics, Scanners, Data modeling, Matrices, Image sensors, Pigments

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Proceedings Article | 4 April 2022 Presentation + Paper

Synthesis of annotated pathological retinal OCT data with pathology-induced deformations

Hristina Uzunova, Leonie Basso, Jan Ehrhardt, Heinz Handels

Proceedings Volume 12033, 120333K (2022) https://doi.org/10.1117/12.2611126

KEYWORDS: Image segmentation, Optical coherence tomography, Pathology, Neural networks, Data modeling, Medical imaging, Image processing, Visualization, Tumors

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Proceedings Article | 15 March 2019 Paper

A probabilistic approach for the registration of images with missing correspondences

Julia Krüger, Jan Ehrhardt, Sandra Schultz, Heinz Handels

Proceedings Volume 10949, 1094925 (2019) https://doi.org/10.1117/12.2511121

KEYWORDS: Image registration, Pathology, Expectation maximization algorithms, 3D image processing, Image segmentation, Medical imaging, Brain, Statistical modeling

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Proceedings Article | 15 March 2019 Presentation + Paper

Interpretable explanations of black box classifiers applied on medical images by meaningful perturbations using variational autoencoders

Hristina Uzunova, Jan Ehrhardt, Timo Kepp, Heinz Handels

Proceedings Volume 10949, 1094911 (2019) https://doi.org/10.1117/12.2511964

KEYWORDS: Pathology, Medical imaging, Image segmentation, Optical coherence tomography, Neural networks, Brain, Magnetic resonance imaging, Image classification

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Proceedings Article | 15 March 2019 Paper

Bayesian inference for uncertainty quantification in point-based deformable image registration

Sandra Schultz, Julia Krüger, Heinz Handels, Jan Ehrhardt

Proceedings Volume 10949, 109491S (2019) https://doi.org/10.1117/12.2512988

KEYWORDS: Image registration, Medical imaging, Data modeling, Pathology, Bayesian inference, Neuroimaging, Brain, Image processing, Magnetic resonance imaging, Image fusion

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Proceedings Article | 2 March 2018 Presentation + Paper

A multilevel Markov Chain Monte Carlo approach for uncertainty quantification in deformable registration

Sandra Schultz, Heinz Handels, Jan Ehrhardt

Proceedings Volume 10574, 105740O (2018) https://doi.org/10.1117/12.2293588

KEYWORDS: Image registration, Brain, Monte Carlo methods, Statistical analysis, Pathology

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Proceedings Article | 21 March 2016 Paper

Multi-level approach for statistical appearance models with probabilistic correspondences

Julia Krüger, Jan Ehrhardt, Heinz Handels

Proceedings Volume 9784, 978433 (2016) https://doi.org/10.1117/12.2214885

KEYWORDS: Analog electronics, Statistical modeling, Model-based design, Process modeling, Data modeling, Shape analysis, Image analysis, Probability theory, Optimization (mathematics), Image segmentation, Visualization, Mathematical modeling, Krypton, Medical imaging

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Proceedings Article | 20 March 2015 Paper

Estimation of corresponding locations in ipsilateral mammograms: a comparison of different methods

Matthias Wilms, Julia Krüger, Mirko Marx, Jan Ehrhardt, Arpad Bischof, Heinz Handels

Proceedings Volume 9414, 94142B (2015) https://doi.org/10.1117/12.2081862

KEYWORDS: Breast, Mammography, Nipple, Chest, 3D modeling, Image compression, Data modeling, Breast cancer, Computer aided diagnosis and therapy, Tissues

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Proceedings Article | 21 March 2014 Paper

Statistical shape and appearance models without one-to-one correspondences

Jan Ehrhardt, Julia Krüger, Heinz Handels

Proceedings Volume 9034, 90340U (2014) https://doi.org/10.1117/12.2043531

KEYWORDS: Image segmentation, Data modeling, Statistical modeling, Process modeling, Lung, Visual process modeling, Shape analysis, Image registration, Expectation maximization algorithms, Optimization (mathematics)

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Proceedings Article | 21 March 2014 Paper

Joint multi-object registration and segmentation of left and right cardiac ventricles in 4D cine MRI

Jan Ehrhardt, Timo Kepp, Alexander Schmidt-Richberg, Heinz Handels

Proceedings Volume 9034, 90340M (2014) https://doi.org/10.1117/12.2043583

KEYWORDS: Image segmentation, Image registration, Magnetic resonance imaging, Heart, Blood, 3D image processing, 3D modeling, Image processing algorithms and systems, Image processing, Distance measurement

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Proceedings Article | 12 March 2014 Paper

Statistical analysis of surrogate signals to incorporate respiratory motion variability into radiotherapy treatment planning

Matthias Wilms, Jan Ehrhardt, René Werner, Mirko Marx, Heinz Handels

Proceedings Volume 9036, 90360J (2014) https://doi.org/10.1117/12.2043568

KEYWORDS: Statistical analysis, Motion models, Tumors, Monte Carlo methods, 4D CT imaging, Data modeling, Statistical modeling, Radiotherapy, Spirometry, Motion measurement

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Proceedings Article | 13 March 2013 Paper

Breast compression simulation using ICP-based B-spline deformation for correspondence analysis in mammography and MRI datasets

Julia Krüger, Jan Ehrhardt, Arpad Bischof, Heinz Handels

Proceedings Volume 8669, 86691D (2013) https://doi.org/10.1117/12.2006356

KEYWORDS: Breast, Magnetic resonance imaging, Mammography, 3D image processing, Image registration, Tissues, 3D acquisition, Image segmentation, Computer simulations, Image compression

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Proceedings Article | 13 March 2013 Paper

Surrogate-based diffeomorphic motion estimation for radiation therapy: comparison of multivariate regression approaches

Matthias Wilms, René Werner, Jan Ehrhardt, Alexander Schmidt-Richberg, Maximilian Blendowski, Heinz Handels

Proceedings Volume 8669, 866915 (2013) https://doi.org/10.1117/12.2002428

KEYWORDS: Motion estimation, Principal component analysis, Radiotherapy, Tumors, Lung, Motion models, Motion measurement, 4D CT imaging, Chest, Simulation of CCA and DLA aggregates

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Proceedings Article | 13 March 2013 Paper

Assessing accuracy of non-linear registration in 4D image data using automatically detected landmark correspondences

René Werner, Christine Duscha, Alexander Schmidt-Richberg, Jan Ehrhardt, Heinz Handels

Proceedings Volume 8669, 86690Z (2013) https://doi.org/10.1117/12.2002454

KEYWORDS: Image registration, Lung, Liver, Computed tomography, Infrared imaging, 3D image processing, Distance measurement, Information technology, Image restoration, Data centers

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Proceedings Article | 17 February 2012 Paper

Model-based risk assessment for motion effects in 3D radiotherapy of lung tumors

René Werner, Jan Ehrhardt, Alexander Schmidt-Richberg, Heinz Handels

Proceedings Volume 8316, 83160C (2012) https://doi.org/10.1117/12.911385

KEYWORDS: 3D modeling, Lung, Motion models, Tumors, Radiotherapy, 4D CT imaging, Motion estimation, 3D image processing, Computed tomography, Model-based design

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Proceedings Article | 14 February 2012 Paper

Pulmonary lobe segmentation with level sets

Alexander Schmidt-Richberg, Jan Ehrhardt, Matthias Wilms, René Werner, Heinz Handels

Proceedings Volume 8314, 83142V (2012) https://doi.org/10.1117/12.911378

KEYWORDS: Image segmentation, Lung, Image quality, Image enhancement, Computed tomography, Image processing, Diagnostics, Medical imaging, Silicon, Image registration

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Proceedings Article | 14 February 2012 Paper

Automatic correspondence detection in mammogram and breast tomosynthesis images

Jan Ehrhardt, Julia Krüger, Arpad Bischof, Jörg Barkhausen, Heinz Handels

Proceedings Volume 8314, 831421 (2012) https://doi.org/10.1117/12.911305

KEYWORDS: Mammography, Breast, 3D image processing, Image registration, Digital mammography, Acquisition tracking and pointing, Tomography, Tissues, Image acquisition, 3D image reconstruction

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Two-dimensional mammography is the major imaging modality in breast cancer detection. A disadvantage of mammography is the projective nature of this imaging technique. Tomosynthesis is an attractive modality with the potential to combine the high contrast and high resolution of digital mammography with the advantages of 3D imaging. In order to facilitate diagnostics and treatment in the current clinical work-flow, correspondences between tomosynthesis images and previous mammographic exams of the same women have to be determined. In this paper, we propose a method to detect correspondences in 2D mammograms and 3D tomosynthesis images automatically. In general, this 2D/3D correspondence problem is ill-posed, because a point in the 2D mammogram corresponds to a line in the 3D tomosynthesis image. The goal of our method is to detect the "most probable" 3D position in the tomosynthesis images corresponding to a selected point in the 2D mammogram. We present two alternative approaches to solve this 2D/3D correspondence problem: a 2D/3D registration method and a 2D/2D mapping between mammogram and tomosynthesis projection images with a following back projection. The advantages and limitations of both approaches are discussed and the performance of the methods is evaluated qualitatively and quantitatively using a software phantom and clinical breast image data. Although the proposed 2D/3D registration method can compensate for moderate breast deformations caused by different breast compressions, this approach is not suitable for clinical tomosynthesis data due to the limited resolution and blurring effects perpendicular to the direction of projection. The quantitative results show that the proposed 2D/2D mapping method is capable of detecting corresponding positions in mammograms and tomosynthesis images automatically for 61 out of 65 landmarks. The proposed method can facilitate diagnosis, visual inspection and comparison of 2D mammograms and 3D tomosynthesis images for the physician.

Proceedings Article | 15 March 2011 Paper

Direction-dependent level set segmentation of cerebrovascular structures

Nils Daniel Forkert, Dennis Säring, Till Illies, Jens Fiehler, Jan Ehrhardt, Heinz Handels, Alexander Schmidt-Richberg

Proceedings Volume 7962, 79623S (2011) https://doi.org/10.1117/12.877942

KEYWORDS: Image segmentation, Image enhancement, Fuzzy logic, Visualization, Brain, 3D image processing, Image filtering, Tissues, 3D-TOF imaging, Health informatics

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Proceedings Article | 11 March 2011 Paper

Landmark-driven parameter optimization for non-linear image registration

Alexander Schmidt-Richberg, René Werner, Jan Ehrhardt, Jan-Christoph Wolf, Heinz Handels

Proceedings Volume 7962, 79620T (2011) https://doi.org/10.1117/12.877059

KEYWORDS: Image registration, Medical imaging, Lung, Image fusion, Motion estimation, Distance measurement, Image processing, 4D CT imaging, Gold, Computed tomography

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Proceedings Article | 13 March 2010 Paper

Direction-dependent regularization for improved estimation of liver and lung motion in 4D image data

Alexander Schmidt-Richberg, Jan Ehrhardt, René Werner, Heinz Handels

Proceedings Volume 7623, 76232Y (2010) https://doi.org/10.1117/12.844194

KEYWORDS: Motion estimation, Image registration, Lung, Liver, Motion models, Magnetic resonance imaging, Physiology, Image segmentation, Data modeling, 4D CT imaging

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Proceedings Article | 13 March 2010 Paper

A statistical shape and motion model for the prediction of respiratory lung motion

Jan Ehrhardt, René Werner, Alexander Schmidt-Richberg, Heinz Handels

Proceedings Volume 7623, 762353 (2010) https://doi.org/10.1117/12.844263

KEYWORDS: Motion models, Data modeling, Lung, Image registration, Principal component analysis, Statistical analysis, Model-based design, Statistical modeling, Motion estimation, 3D modeling

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Proceedings Article | 13 March 2010 Paper

Coupled level set segmentation using a point-based statistical shape model relying on correspondence probabilities

Heike Hufnagel, Jan Ehrhardt, Xavier Pennec, Alexander Schmidt-Richberg, Heinz Handels

Proceedings Volume 7623, 762318 (2010) https://doi.org/10.1117/12.844289

KEYWORDS: Image segmentation, Statistical modeling, Kidney, Data modeling, Bone, Computed tomography, Head, Shape analysis, Evolutionary algorithms, Affine motion model

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Proceedings Article | 27 March 2009 Paper

Validation and comparison of a biophysical modeling approach and non-linear registration for estimation of lung motion fields in thoracic 4D CT data

Rene Werner, Jan Ehrhardt, Alexander Schmidt-Richberg, Heinz Handels

Proceedings Volume 7259, 72590U (2009) https://doi.org/10.1117/12.811130

KEYWORDS: Lung, Data modeling, Motion models, Tumors, Motion estimation, Image registration, Biological research, Physiology, 4D CT imaging, Model-based design

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Proceedings Article | 12 March 2008 Paper

Modeling respiratory lung motion: a biophysical approach using finite element methods

Rene Werner, Jan Ehrhardt, Rainer Schmidt, Heinz Handels

Proceedings Volume 6916, 69160N (2008) https://doi.org/10.1117/12.769155

KEYWORDS: Lung, Motion models, Tumors, Data modeling, Finite element methods, Process modeling, 3D modeling, Computed tomography, 4D CT imaging, Tissues

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Proceedings Article | 11 March 2008 Paper

Comparison of statistical shape models built on correspondence probabilities and one-to-one correspondences

Heike Hufnagel, Xavier Pennec, Jan Ehrhardt, Nicholas Ayache, Heinz Handels

Proceedings Volume 6914, 69144T (2008) https://doi.org/10.1117/12.771136

KEYWORDS: Statistical modeling, Expectation maximization algorithms, Data modeling, Shape analysis, Principal component analysis, 3D modeling, Image segmentation, Optimization (mathematics), Clouds, Brain

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Proceedings Article | 11 March 2008 Paper

Simultaneous segmentation and motion estimation in 4D-CT data using a variational approach

Jan Ehrhardt, Alexander Schmidt-Richberg, Heinz Handels

Proceedings Volume 6914, 691437 (2008) https://doi.org/10.1117/12.768228

KEYWORDS: Image segmentation, Image registration, Liver, Motion estimation, 4D CT imaging, Data modeling, Computed tomography, Tissues, Tumors, Motion models

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Proceedings Article | 5 March 2007 Paper

Analysis of free breathing motion using artifact reduced 4D CT image data

Jan Ehrhardt, Rene Werner, Thorsten Frenzel, Wei Lu, Daniel Low, Heinz Handels

Proceedings Volume 6512, 65121N (2007) https://doi.org/10.1117/12.708171

KEYWORDS: Tumors, Lung, Motion analysis, 4D CT imaging, Image segmentation, Skin, Computed tomography, Visualization, 3D image reconstruction, Optical flow

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Proceedings Article | 10 March 2006 Paper

Optical flow based interpolation of temporal image sequences

Jan Ehrhardt, Dennis Säring, Heinz Handels

Proceedings Volume 6144, 61442K (2006) https://doi.org/10.1117/12.652559

KEYWORDS: Optical flow, Magnetic resonance imaging, Image registration, Medical imaging, Tomography, Temporal resolution, Imaging devices, Algorithm development, Image acquisition, Data acquisition

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Proceedings Article | 10 March 2006 Paper

Reconstruction of 4D-CT data sets acquired during free breathing for the analysis of respiratory motion

Jan Ehrhardt, Rene Werner, Thorsten Frenzel, Dennis Säring, Wei Lu, Daniel Low, Heinz Handels

Proceedings Volume 6144, 614414 (2006) https://doi.org/10.1117/12.651730

KEYWORDS: Computed tomography, 4D CT imaging, Optical flow, Data acquisition, Radiotherapy, Motion analysis, Spirometry, Scanners, Image registration, Visualization

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Proceedings Article | 21 May 1999 Paper

Automatic landmark identification in 3D image volumes by topography conserving approximation of contour data

Heinrich Overhoff, Andre Mastmeyer, Jan Ehrhardt

Proceedings Volume 3661, (1999) https://doi.org/10.1117/12.348619

KEYWORDS: Natural surfaces, Image segmentation, Associative arrays, Tomography, X-rays, Neck, Mathematical modeling, 3D image processing, Diagnostics, Image processing

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