PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 9691573

An improved boundary element method for realistic volume-conductor modeling.

M Fuchs·R Drenckhahn·H A Wischmann·M Wagner
View original source ↗Export metadata ↓

Abstract

An improved boundary element method (BEM) with a virtual triangle refinement using the vertex normals, an optimized auto solid angle approximation, and a weighted isolated problem approach is presented. The performance of this new approach is compared to analytically solvable spherical shell models and highly refined reference BEM models for tangentially and radially oriented dipoles at different eccentricities. The lead fields of several electroencephalography (EEG) and magnetoencephalography (MEG) setups are analyzed by singular-value decompositions for realistically shaped volume-conductor models. Dipole mislocalizations due to simplified volume-conductor models are investigated for EEG and MEG examinations for points on a three dimensional (3-D) grid with 10-mm spacing inside the conductor and all principal dipole orientations. The applicability of the BEM in view of the computational effort is tested with a standard workstation. Finally, an application of the new method to epileptic spike data is studied and the results are compared to the spherical-shells approximation.

Explore related subjects

Body Fluid CompartmentsComputer SimulationElectric ConductivityElectroencephalographyEpilepsyHeadHumansImage Processing, Computer-AssistedMagnetic Resonance ImagingMagnetoencephalographyModels, BiologicalSurface PropertiesJournal Article

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

M Fuchs, R Drenckhahn, H A Wischmann, M Wagner. 1998. An improved boundary element method for realistic volume-conductor modeling.. https://doi.org/10.1109/10.704867

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2006

Bradykinin shifts endothelial fluid passage from para- to transcellular routes.

The signalling peptide bradykinin (BK) is implicated in inflammation and angiogenesis. It promotes fluid transport from blood vessels to interstitial space, and thus facilitates oedema formation. To clarify whether paracellular or transcellular pathways mediate this effect, we investigated the BK-stimulated fluid transport across endothelial monolayers in vitro by comparison of electrical and fluorescence methods. Electrical cell impedance sensing monitored a biphasic response of cell layers to BK with high time resolution: a short decrease (18%, 1 min) was followed by a more sustained increase in paracellular resistance (30%, 10 min). The two phases can be assigned to second messengers of the BK-signalling pathway: Ca(2+) for the decrease and cyclic adenosine monophosphate for the rise of resistance, respectively. Despite tightening of the intercellular clefts, BK increased the fluid permeability by 39%, indicating transcellular fluid transport. Additionally, BK stimulated both in- and outwardly directed membrane trafficking as assessed by vesicular fluid uptake (by 49%) and secretion of von Willebrandt factor (by 85%). In conclusion, the combination of electrical and fluorescence data suggests that BK induces a shift from para- to transcellular fluid transport across endothelium.

Body Fluid Compartments↗
PubMed2006

Beta2-microglobulin, a uremic toxin with a double meaning.

beta(2)M is a strong and independent indicator of hemodialysis patient outcomes and an excellent surrogate for middle molecules, and deserves to be routinely monitored and incorporated into dialysis adequacy targets. beta(2)M has a double meaning, reflecting both dialysis efficacy in terms of solute mass transfer and patient bioactivity. The work of Ward et al. in this issue warrants a study to test the hypothesis that long daily hemodiafiltration treatment would be the optimal renal replacement modality to improve dialysis patient outcomes.

Body Fluid Compartments↗