title: Towards a computational method for imaging the extracellular potassium concentration during regional ischemia.
abstract: We investigate the possibility of using body surface potential maps to image the extracellular potassium concentration during regional ischemia. The problem is formulated as an inverse problem based on a linear approximation of the bidomain model, where we minimize the difference between the results of the model and observations of body surface potentials. The minimization problem is solved by a one-shot technique, where the original PDE system, an adjoint problem, and the relation describing the minimum, are solved simultaneously. This formulation of the problem requires the solution of a 5 x 5 system of linear partial differential equations. The performance of the model is investigated by performing tests based on synthetic data. We find that the model will in many cases detect the correct position and approximate size of the ischemic regions, while some cases are more difficult to locate. It is observed that a simple post-processing of the results produces images that are qualitatively very similar to the true solution.
authors.affiliation: Center for Biomedical Computing at Simula Research Laboratory, P.O. Box 134, 1325 Lysaker, Norway. bjornn@simula.no
authors.forename: Bjørn Fredrik
authors.initials: BF
authors.lastname: Nielsen
authors.forename: Xing
authors.initials: X
authors.lastname: Cai
authors.forename: Joakim
authors.initials: J
authors.lastname: Sundnes
authors.forename: Aslak
authors.initials: A
authors.lastname: Tveito
mesh_terms: D000465:Algorithms; D016477:Artifacts; D003198:Computer Simulation; D003952:Diagnostic Imaging / Q000379:methods*; D004562:Electrocardiography; D055724:Electrophysiological Phenomena / Q000502:physiology; D045604:Extracellular Fluid / Q000378:metabolism*; D020342:Finite Element Analysis; D006801:Humans; D016014:Linear Models; D008955:Models, Cardiovascular; D017202:Myocardial Ischemia / Q000175:diagnosis / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism; D011188:Potassium / Q000032:analysis / Q000378:metabolism*
chemical_list: D011188:Potassium