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selected Abstracts, Posters, Talks

Shape-based Classification and Domain Adaptation for Alzheimer's Disease Diagnostics. C.Wachinger,M.Reuter. Human Brain Mapping 2016, Geneva. Abstract / Poster.
BrainPrint - A Compact Shape Description of the Brain for Identification and Classification. C.Wachinger,...,M.Reuter. Human Brain Mapping 2015, Honolulu. Abstract / Poster.
Impact of varying acquisition parameters on cortical thickness/volume derived from MEMPRAGE scans. R.Mair, M.Reuter, A.v.d.Kouwe. Human Brain Mapping 2015, Honolulu. Abstract / Poster.
Characterization of cortical surface reconstruction for sub-millimeter 7T MPRAGE using FreeSurfer. N.Zaretskaya, B.Fischl, M.Reuter, .... Human Brain Mapping 2015, Honolulu. Abstract / Poster.
Head Motion in MRI Causes Bias in Structural Brain Measurements. M.Reuter, et al. Human Brain Mapping 2014, Hamburg. Abstract / Poster.
Shape Analysis of 101 Healty Human Brains. A.Klein, et al. Human Brain Mapping 2014, Hamburg. Abstract / Poster.
Comparison of Subcortical Morphometry in Alzheimer's Disease and HIV + Subjects. B.S.C.Wade, et al. Human Brain Mapping 2014, Hamburg. Abstract / Poster.
Cortical Thickness/Volume Measured with Variable Acceleration in Young and Elderly Populations. R.Mair, M.Reuter, A.v.d.Kouwe. Human Brain Mapping 2014, Hamburg. Abstract / Poster.
Placement in Scanner Causes Significant Diagnostic Errors in Brain Tumor Treatment Assessment. M.Reuter, et al. Human Brain Mapping 2013, Seattle. Abstract / Poster. [PDF] details

Brain tumor treatment response is assessed by manual 2D size measurements of the enhancing tumor taken by a radiologist. Here we show the high variability of these measurements caused by different head placement (and slice orientations) in the scanner. With no anatomical changes, all subjects in this study would have been characterized as 'progresive disease' in spite of no anatomical changes. hide

Robust registration of multi-modal images. C.Wachinger, et al. Human Brain Mapping 2013, Seattle. Abstract / Poster. [PDF] details

This abstract/poster describes a novel methods for highly accurate cross modal/sequence registration in the presence of outliers (such as jaw, neck, skull strip difference or differences caused by enhancing tumor). Another application is the registration of histology images containing artifacts such as rips, tears and local deformations from the slicing procedure. The method will be made available as an extension to mri_robust_register (see [Reuter..NI 2010]) in future FreeSurfer releases. hide

Increasing Statistical Power by Modeling Spatiotemporal Correlations in Longitudinal Neuroimage Data. J.L.Bernal-Rusiel, et al. Human Brain Mapping 2013, Seattle. Abstract / Poster.
Mapping T1rho and T2rho relaxation across the whole brain with robust MRI sequences. O.Andronesi, et al. Human Brain Mapping 2013, Seattle. Abstract / Poster.
Quantitative Validation of Morphometric Data from a Rapid 2-Minute Multi-Echo MPRAGE Scan. R.Mair, et al. Human Brain Mapping 2013, Seattle. Abstract / Poster.
Cytoarchitecture of cortex imaged by Optical Coherence Tomography. C.Magnain, et al. Human Brain Mapping 2013, Seattle. Abstract / Poster.
Exploring the biomarker cascade model: Relating cortical volume loss to [11C]PIB, [18F]FDG and MMSE over time in Alzheimer's disease patients and normal controls. S.Adriaanse, K.v.Dijk, R.Ossenkoppele, M.Reuter et al. Alzheimer's & Dementia 8(4):P348, 2012. [DOI-Link] details

Structural brain changes in the form of neuronal atrophy are important diagnostic features of Alzheimer's disease (AD) when patients present with symptoms. Amyloid-plaque formation and hypometabolism are believed to precede atrophy and followed by cognitive decline. The present longitudinal study examined how cortical volume loss over time was related to AD pathology and global cognition in both AD patients and controls. Brain volume loss over time was most strongly related to change over time in metabolism as well as to lower MMSE score at follow-up in AD patients. It also seemed to be related to amyloid plaque formation at both time-points in healthy controls, which may be an indicator of early subclinical pathological brain changes in cognitively normal subjects. hide

Registration of Histology and MRI using Blockface as Intermediate Space. M.Reuter, P.Sand, et al. Human Brain Mapping 2012, Beijing. Abstract / Poster. [PDF] details

Registering histological images with MR data is difficult because of geometric differences caused by physical deformations as well as tissue appearance. Here we use blockface images (top surface of tissue block) as intermediate space. We register the blockface volume with an MRI (3D) and then individual histological images with MR slices (2D). hide

Robust and Accurate Contralateral Registration for Pose Normalization and Tumor Segmentation. M.Reuter, H.D.Rosas, B.Fischl. Human Brain Mapping 2012, Beijing. Abstract / Poster. [PDF] details

Radiotherapy or surgery of brain tumors require prior tumor segmentation. Automatic tumor segmentation and quantitative analysis poses challenging computational problems. We aim at providing sophisticated registration procedures, expected to improve segmentation results in existing segmentation approaches and show that joint probabilities in cross-modal registration and outlier regions in robust contralateral registration can further be used to guide automatic tumor segmentation. Moreover inverse consitent contralateral registration into a half-way space results in an upright and straight head position (pose normalization). hide

Comparison of cortical surface reconstructions from MP2RAGE data at 3T and 7T. K.Fujimoto, J. Polimeni et al. Human Brain Mapping 2011, Quebec City. Abstract / Poster.
Unbiased Longitudinal Processing of Structural MRI Data in FreeSurfer. M.Reuter, H.D.Rosas, B.Fischl. Human Brain Mapping 2011, Quebec City. Abstract / Poster. [PDF]
Accurate Inverse Consistent Robust Registration. M. Reuter, H.D. Rosas, B. Fischl. Human Brain Mapping 2010, Barcelona. Abstract / Poster. [PDF] details

In order to accurately study disease effects or disease-modifying therapies using computational anatomy, anatomical change needs to be quantified in medical images. Since the object of interest is usually located differently in each acquired image, geometric transformations are necessary to register the input images into a common space. A highly accurate registration is desirable for motion correction of images taken in the same session, across time in longitudinal studies or simply to initialize non-linear warps. This work describes a method based on robust statistics to register images in the presence of differences, such as jaw movement, differential MR distortions and atrophy. Our approach guarantees inverse consistency (symmetry) and can deal with different intensity scales. The resulting registrations are highly accurate and show superior robustness with respect to noise, intensity scaling and outliers when compared to state-of-the-art registration tools such as FLIRT (in FSL) or the coregistration tool in SPM. hide

Unbiased Robust Template Estimation for Longitudinal Analysis in FreeSurfer. M. Reuter, H.D. Rosas, B. Fischl. Human Brain Mapping 2010, Barcelona. Abstract / Poster. [PDF] details

Compared with cross-sectional studies, a longitudinal design can significantly reduce the confounding effect of inter-individual morphological variability by using each subject as his or her own control. As a result, longitudinal imaging studies are increasing in popularity in various aspects of neuroscience. Changes in gray matter that makes up the cortical sheet are for example manifested in aging, Alzheimer's disease, Huntington's disease, multiple sclerosis and schizophrenia. In vivo cortical thickness measures could be useful as marker of disease progression or onset. Longitudinal imaging-based biomarkers are thus of great potential utility in evaluating the efficiency of disease-modifying therapies. For these reasons, developing more robust and reliable measures of cortical, subcortical and white matter atrophy may have a profound clinical impact. The current methods that utilize cross-sectional approaches, in which images are processed individually introduce the natural variability of the brain as a confound. We sought to develop and validate a longitudinal approach that takes advantage of intra-subject longitudinal acquired scans to improve the sensitivity and reliability of automatic neuro-imaging morphometic measures. hide

Invited Talk: High Order Laplace-Beltrami Computations for Non-Rigid Shape Analysis and Processing. M. Reuter. SMI'08, Shape Modeling International Stony Brook, June 2008.
Invited Talk: Spectral methods for non-rigid shape analysis. M. Reuter. Workshop on 3D Shape Characterization, University Konstanz, Dec. 2007.
Talk: Global Isometry Invariant Shape Analysis. M. Reuter. SIAM GD07, Geometric Design and Computing Conference, 2007.
Invited Talk: Subdivision Multivariate Solver in the Barycentric Bernstein Basis. M. Reuter. SIAM GD07, Geometric Design and Computing Conference, 2007.
Global Medical Shape Analysis Using the Volumetric Laplace Spectrum. M. Reuter, M. Niethammer, F.-E. Wolter, S. Bouix, M. Shenton. Proceedings of the 2007 Int. Conf. on Cyberworlds, NASA-GEM Workshop, IEEE Computer Society, pp.417-426, 2007. [PDF] [BibTex] [DOI-Link] details

This paper proposes to use the volumetric Laplace spectrum as a global shape descriptor for medical shape analysis. The approach allows for shape comparisons using minimal shape preprocessing. In particular, no registration, mapping, or remeshing is necessary. All computations can be performed directly on the voxel representations of the shapes. The discriminatory power of the method is tested on a population of female caudate shapes (subcortical gray matter structure of the brain, involved in memory function, emotion processing, and learning) of normal control subjects and of subjects with schizotypal personality disorder. The behavior and properties of the volumetric Laplace spectrum are discussed extensively for both the Dirichlet and Neumann boundary condition showing advantages of the Neumann spectra. Both, the computations of spectra on 3D voxel data for the purpose of shape matching as well as the use of the Neumann spectrum for shape analysis are completely new. hide

Can one hear Shape?. M. Reuter. PAMM Proceedings of GAMM07 and ICIAM07, Vol 7, Issue 1, 6th International Congress of Industrial and Applied Mathematics, SIAM, October 2008. [PDF] [BibTex] [DOI-Link] details

The question "Can one hear the shape of a drum" has been asked in several contexts before (e.g., by Bers and Kac). It is a pictorial way of asking if the eigenvalues of the Laplacian on a given domain completely characterize its shape, in other words, if the spectrum is a complete shape descriptor (which it is not in general). In this talk we will give an overview on how the computation of the spectra can be accomplished using FEM for manifolds in 2D and 3D (e.g. iso-surfaces, boundary representations, solid bodies, vector fields...) with the Dirichlet and Neumann boundary condition. We demonstrate that it is computational feasible to numerically extract geometric properties (volume, area, boundary length and even the Euler characteristic) from the first eigenvalues. Since the spectrum contains geometrical information and since it is an isometry invariant and therefore independent of the object's representation, parametrization, spatial position, and optionally of its size, it is optimally suited to be used as a fingerprint (Shape-DNA) in contemporary computer graphics applications like database retrieval, quality assessment, and shape matching in fields like CAD, medicine or engineering. hide

Laplace-Spectra as Fingerprints for Shape Matching. M. Reuter, F.-E. Wolter and N. Peinecke. Proceedings of the ACM Symposium on Solid and Physical Modeling, pp.101-106, June 2005. [PDF] [BibTex] [DOI-Link] details

This paper introduces a method to extract fingerprints of any surface or solid object by taking the eigenvalues of its respective Laplace-Beltrami operator. Using an object's spectrum (i.e. the family of its eigenvalues) as a fingerprint for its shape is motivated by the fact that the related eigenvalues are isometry invariants of the object. Employing the Laplace-Beltrami spectra (not the spectra of the mesh Laplacian) as fingerprints of surfaces and solids is a novel approach in the field of geometric modeling and computer graphics. Those spectra can be calculated for any representation of the geometric object (e.g. NURBS or any parametrized or implicitly represented surface or even for polyhedra). Since the spectrum is an isometry invariant of the respective object this fingerprint is also independent of the spatial position. Additionally the eigenvalues can be normalized so that scaling factors for the geometric object can be obtained easily. Therefore checking if two objects are isometric needs no prior alignment (registration / localization) of the objects, but only a comparison of their spectra. With the help of such fingerprints it is possible to support copyright protection, database retrieval and quality assessment of digital data representing surfaces and solids. hide

Poster: "Eigenvalues of the Laplace-Beltrami operator for shape analysis". M. Reuter. 1st Reporting colloquium of the GRK 615, Hannover, Germany, January 2003.
Seminar Paper: Knot Theorie - Polynom Invariants. M. Reuter. (german). [PDF] details

This paper gives an overview on one of the most successful methods to detect the dissimilarity of knots. A polynomial is assigned to every knot. Since these polynomials can be computed from any knot projection and since they always stay the same for the same knot they are called knot invariants. If two such polynomials differ, it is sure that they cannot describe the same knot. First the Jones polynomial is derived together with the prove that it is a knot invariant (using the Reidemeister moves). Afterwards a closer look is taken at alternating knots and their invariants. The final section describes the Alexander and the HOMFLY polynomials and their properties. hide
Martin Reuter - MIT - Cambridge, MA, USA - EMail:
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