Evaluation of approaches to regularizing minimum norm estimate
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1
Institute of Mathematics, Physics and Mechanics, Slovenia
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2
Jozef Stefan Institute, Slovenia
Minimum-norm estimate (MNE) method is a well-known technique for reconstructing distributed current sources from a large number of magnetocardiograms, simultaneously recorded above the chest. The MNE assumes that the normal component of the magnetic field Bi (i=1,...,m) detected by m magnetometers can be expressed as a linear function of n unknown source strengths Jj (j=1,...,n), i.e., L J = B, where Lij (m x n) is the lead field matrix, accounting for the sensitivity of the ith magnetometer to the presence of the jth source. The matrix L can be computed for a given realistic volume conductor using the boundary element method. The main challenge of the expression L J = B, is its intrinsic ill-posedness, which requires use of regularization techniques to smooth out the solution; the amount of smoothing that is still acceptable is a subject of ongoing research. The objective of this paper is to systematically compare various mathematical techniques in regularizing the MNE problem. For the purposes of the forward computations, we employed simple source models (single and multiple dipoles) and an anatomically accurate model of the human ventricular myocardium, all placed within the homogeneous torso model. The current distributions were recovered on the epicardial surface using 14 different regularization techniques, representing the following 3 classes of regularizations: Tikhonov-based regularizations, iterative methods, and non-quadratic regularizations.
Conference:
Biomag 2010 - 17th International Conference on Biomagnetism , Dubrovnik, Croatia, 28 Mar - 1 Apr, 2010.
Presentation Type:
Poster Presentation
Topic:
MCG: Instrumentation, Modeling, Basic and Clinical Studies
Citation:
Jazbinšek
V,
MilaniČ
M and
Hren
R
(2010). Evaluation of approaches to regularizing minimum norm estimate.
Front. Neurosci.
Conference Abstract:
Biomag 2010 - 17th International Conference on Biomagnetism .
doi: 10.3389/conf.fnins.2010.06.00325
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Received:
06 Apr 2010;
Published Online:
06 Apr 2010.
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Correspondence:
Vojko Jazbinšek, Institute of Mathematics, Physics and Mechanics, Ljubljana, Slovenia, vojko.jazbinsek@imfm.uni-lj.si