title: Computing volume potentials for noninvasive imaging of cardiac excitation.
abstract: BACKGROUND
  In noninvasive imaging of cardiac excitation, the use of body surface potentials (BSP) rather than body volume potentials (BVP) has been favored due to enhanced computational efficiency and reduced modeling effort. Nowadays, increased computational power and the availability of open source software enable the calculation of BVP for clinical purposes. In order to illustrate the possible advantages of this approach, the explanatory power of BVP is investigated using a rectangular tank filled with an electrolytic conductor and a patient specific three dimensional model.
  
  
  METHODS
  MRI images of the tank and of a patient were obtained in three orthogonal directions using a turbo spin echo MRI sequence. MRI images were segmented in three dimensional using custom written software. Gmsh software was used for mesh generation. BVP were computed using a transfer matrix and FEniCS software.
  
  
  RESULTS
  The solution for 240,000 nodes, corresponding to a resolution of 5 mm throughout the thorax volume, was computed in 3 minutes. The tank experiment revealed that an increased electrode surface renders the position of the 4 V equipotential plane insensitive to mesh cell size and reduces simulated deviations. In the patient-specific model, the impact of assigning a different conductivity to lung tissue on the distribution of volume potentials could be visualized.
  
  
  CONCLUSIONS
  Generation of high quality volume meshes and computation of BVP with a resolution of 5 mm is feasible using generally available software and hardware. Estimation of BVP may lead to an improved understanding of the genesis of BSP and sources of local inaccuracies.
authors.affiliation: Department of Cardiology, Haga Teaching Hospital, The Hague, The Netherlands.
authors.forename: A W Maurits
authors.initials: AW
authors.lastname: van der Graaf
authors.forename: Pranav
authors.initials: P
authors.lastname: Bhagirath
authors.forename: Vincent J H M
authors.initials: VJ
authors.lastname: van Driel
authors.forename: Hemanth
authors.initials: H
authors.lastname: Ramanna
authors.forename: Jacques
authors.initials: J
authors.lastname: de Hooge
authors.forename: Natasja M S
authors.initials: NM
authors.lastname: de Groot
authors.forename: Marco J W
authors.initials: MJ
authors.lastname: Götte
mesh_terms: D004562:Electrocardiography; D006321:Heart / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008955:Models, Cardiovascular; D012984:Software
keywords: electrocardiography; finite element method; inverse procedure; noninvasive imaging of cardiac excitation