Cardiomagnetic source imaging

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dc.contributor Aalto-yliopisto fi
dc.contributor Aalto University en
dc.contributor.author Pesola, Katja
dc.date.accessioned 2012-02-10T09:50:10Z
dc.date.available 2012-02-10T09:50:10Z
dc.date.issued 2000-05-19
dc.identifier.isbn 951-22-5004-7
dc.identifier.uri https://aaltodoc.aalto.fi/handle/123456789/2265
dc.description.abstract Magnetocardiographic (MCG) source imaging has received increasing interest in recent years. With a high enough localization accuracy of the current sources in the heart, valuable information can be provided, e.g., for the pre-ablative evaluation of arrhythmia patients. Furthermore, preliminary studies indicate that ischemic areas, i.e. areas which are suffering from lack of oxygen, and infarcted regions could be localized from multichannel MCG recordings. In this thesis, the accuracy of cardiomagnetic source imaging results, obtained by using different current source models, was investigated. In addition, the effect of the torso model on the localization accuracy was examined. In some studies, also body surface potential mapping (BSPM) data were used for comparison purposes. A high impact was given to clinical validation, i.e. how the calculation methods would work in patients. The equivalent current dipole (ECD) source model was found to produce accurate (within 3-11 mm) localizations of focal current sources in a thorax phantom and in 15 patients with a non-magnetic stimulation catheter in the heart. The accuracy was found to depend on the signal-to-noise ratio and on the goodness of fit of the localizations. The corresponding accuracy determined from simultaneous multichannel BSPM recordings in 10 patients was 25 mm. In order to localize wider source regions in the heart, distributed source models were also investigated in the thesis. Current density estimates (CDEs) were calculated in the catheter patients and in 13 patients with coronary artery disease (CAD). Promising results were obtained by using second-order Tikhonov regularization in the calculations. CDEs were found to localize both myocardial ischemia in single-vessel CAD patients, as well as more complex chronic ischemia in three-vessel CAD patients. In addition to the ECD and CDE source models, the uniform double layer (UDL) model was used in the source imaging studies. With the UDL model, the whole depolarization of the ventricles can be represented with a single inverse solution. In the validation of the activation time maps calculated from MCG and BSPM recordings, invasively measured epicardial electrograms were used to construct the reference epicardial activation times. The overall patterns of activation in the reference data were reproduced relatively well in the calculated activation time maps. The high quality of the inverse solutions obtained in this thesis prompts the use of cardiomagnetic source imaging in several clinical applications, such as in electrophysiological studies and in the estimation of myocardial viability. en
dc.format.extent 61, [66]
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 K. Pesola, U. Tenner, J. Nenonen, P. Endt, H. Brauer, U. Leder, T. Katila: Multichannel magnetocardiographic measurements with a physical thorax phantom. Med. Biol. Eng. Comp, 37: 2-7, 1999.
dc.relation.haspart R. Fenici, J. Nenonen, K. Pesola, P. Korhonen, J. Lötjönen, M. Mäkijärvi, L. Toivonen, V-P. Poutanen, P. Keto, T. Katila. Nonfluoroscopic localization of an amagnetic stimulation catheter by multichannel magnetocardiography. Pacing Clin. Electrophysiol, 22: 1210-1220, 1999.
dc.relation.haspart K. Pesola, J. Nenonen, R. Fenici, J. Lötjönen, M. Mäkijärvi, P. Fenici, P. Korhonen, K. Lauerma, M. Valkonen, L. Toivonen, T. Katila. Bioelectromagnetic localization of a pacing catheter in the heart. Phys. Med. Biol, 44: 2565-2578, 1999.
dc.relation.haspart K. Pesola, J. Lötjönen, J. Nenonen, I.E. Magnin, K. Lauerma, R. Fenici, T. Katila. The effect of geometric and topologic differences in boundary element models on magnetocardiographic localization accuracy. Accepted for publication in IEEE Transactions on Biomedical Engineering, 2000.
dc.relation.haspart K. Pesola, J. Nenonen, R. Fenici, T. Katila. Comparison of regularization methods when applied to epicardial minimum norm estimates. Biomed. Tech, 42(S1): 273-276, 1997.
dc.relation.haspart K. Pesola, H. Hänninen, K. Lauerma, J. Lötjönen, M. Mäkijärvi, J. Nenonen, P. Takala, L.-M. Voipio-Pulkki, L. Toivonen, T. Katila. Current density estimation on the left ventricular epicardium: A potential method for ischemia localization. Biomed. Tech, 44(S2): 143-146, 1999.
dc.relation.haspart T. Oostendorp, K. Pesola. Non-invasive determination of the activation sequence of the heart: Validation by comparison with invasive human data. In: A. Murray, S. Swiryn (Eds.): Computers in Cardiology, 25: 313-316, 1998.
dc.relation.haspart K. Pesola, T. Oostendorp, J. Nenonen, P. Korhonen, J. Lötjönen, L. Toivonen, T. Katila. Uniform double layer solutions for magnetocardiographic and body surface potential mapping data. In: T. Yoshimoto et al. (Eds.): Recent Advances in Biomagnetism: Proceedings of the 11th International Conference on Biomagnetism, Tohoku University Press, Sendai, 290-293, 1999.
dc.subject.other Medical sciences en
dc.subject.other Physics en
dc.title Cardiomagnetic source imaging 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 magnetocardiography en
dc.subject.keyword inverse problem en
dc.subject.keyword equivalent current dipole en
dc.subject.keyword current density estimation en
dc.subject.keyword uniform double layer en
dc.identifier.urn urn:nbn:fi:tkk-002351
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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