Construction of boundary element models in bioelectromagnetism

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.author Lötjönen, Jyrki
dc.date.accessioned 2012-02-10T09:49:38Z
dc.date.available 2012-02-10T09:49:38Z
dc.date.issued 2000-04-27
dc.identifier.isbn 951-22-4976-6
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/2263
dc.description.abstract Multisensor electro- and magnetoencephalographic (EEG and MEG) as well as electro- and magnetocardiographic (ECG and MCG) recordings have been proved useful in noninvasively extracting information on bioelectric excitation. The anatomy of the patient needs to be taken into account, when excitation sites are localized by solving the inverse problem. In this work, a methodology has been developed to construct patient specific boundary element models for bioelectromagnetic inverse problems from magnetic resonance (MR) data volumes as well as from two orthogonal X-ray projections. The process consists of three main steps: reconstruction of 3-D geometry, triangulation of reconstructed geometry, and registration of the model with a bioelectromagnetic measurement system. The 3-D geometry is reconstructed from MR data by matching a 3-D deformable boundary element template to images. The deformation is accomplished as an energy minimization process consisting of image and model based terms. The robustness of the matching is improved by multi-resolution and global-to-local approaches as well as using oriented distance maps. A boundary element template is also used when 3-D geometry is reconstructed from X-ray projections. The deformation is first accomplished in 2-D for the contours of simulated, built from the template, and real X-ray projections. The produced 2-D vector field is back-projected and interpolated on the 3-D template surface. A marching cube triangulation is computed for the reconstructed 3-D geometry. Thereafter, a non-iterative mesh-simplification method is applied. The method is based on the Voronoi-Delaunay duality on a 3-D surface with discrete distance measures. Finally, the triangulated surfaces are registered with a bioelectromagnetic measurement utilizing markers. More than fifty boundary element models have been successfully constructed from MR images using the methods developed in this work. A simulation demonstrated the feasibility of X-ray reconstruction; some practical problems of X-ray imaging need to be solved to begin tests with real data. en
dc.format.extent 49, [55]
dc.format.mimetype application/pdf
dc.language.iso en en
dc.publisher Helsinki University of Technology en
dc.publisher Teknillinen korkeakoulu fi
dc.relation.haspart J. Lötjönen, P-J. Reissman, I.E. Magnin and T. Katila. Model Extraction from Magnetic Resonance Volume Data Using the Deformable Pyramid. Medical Image Analysis, 3(4): 387-406, 1999.
dc.relation.haspart J. Lötjönen, I.E. Magnin, L. Reinhardt, J. Nenonen and T. Katila. Automatic Reconstruction of 3D Geometry Using 2D Projections and a Geometric Prior Model. Lecture Notes in Computer Science 1679: Medical Image Computing and Computer-Assisted Intervention, MICCAI 99, C. Taylor, A. Colchester (Eds.), Springer, 192-201, 1999.
dc.relation.haspart J. Lötjönen, I.E. Magnin, J. Nenonen and T. Katila. Reconstruction of 3D Geometry Using 2D Profiles and a Geometric Prior Model. IEEE Transactions on Medical Imaging, 18(10): 992-1002, 1999.
dc.relation.haspart J. Lötjönen, P-J. Reissman, I.E. Magnin, J. Nenonen and T. Katila. A Triangulation Method of an Arbitrary Point Set for Biomagnetic Problems. IEEE Transactions on Magnetics, 34(4): 2228-2233, 1998.
dc.relation.haspart R. Fenici, J. Nenonen, K. Pesola, P. Korhonen, J. Lötjönen, M. Mäkijärvi, L. Toivonen, V-P. Poutanen, P. Keto, T. Katila. Non-fluoroscopic localisation of an amagnetic stimulation catheter by multichannel magnetocardiography. Pacing Clin. Electrophysiol, 22: 1210-1220, 1999.
dc.relation.haspart K. Pesola, J. Lötjönen, J. Nenonen, I.E. Magnin, K. Lauerma, R. Fenici and T. Katila. The effect of geometry and topology differences in boundary element models on magnetocardiographic localization accuracy. Accepted for publication in IEEE Transactions on Biomedical Engineering, 2000.
dc.subject.other Medical sciences en
dc.subject.other Physics en
dc.title Construction of boundary element models in bioelectromagnetism en
dc.type G5 Artikkeliväitöskirja fi
dc.description.version reviewed en
dc.contributor.department Department of Engineering Physics and Mathematics en
dc.contributor.department Teknillisen fysiikan ja matematiikan osasto fi
dc.subject.keyword segmentation en
dc.subject.keyword triangulation en
dc.subject.keyword 3-D reconstruction en
dc.subject.keyword registration en
dc.identifier.urn urn:nbn:fi:tkk-002334
dc.type.dcmitype text en
dc.type.ontasot Väitöskirja (artikkeli) fi
dc.type.ontasot Doctoral dissertation (article-based) en
dc.contributor.lab Laboratory of Biomedical Engineering en
dc.contributor.lab Lääketieteellisen tekniikan instituutti fi


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