Validation of a detailed computer model for the electric fields in the brain

Laarne, P.; Eskola, Hannu; Hyttinen, Jari; Suihko, V.; Malmivuo, Jaakko

doi:10.3109/03091909509030281

Cited by 20 publications

(10 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The model applied contains over 20 different organ and tissue types with corresponding resistivities, which are listed in Table 1 [13]. Laarne et al [16] and Kauppinen et al [13] have validated the use of FDM in modeling measurement sensitivity distributions in bioelectric volume conductors. We have previously demonstrated the general effects of implantation on measurement sensitivity in a low-resolution model [26].…”

Section: Finite Difference Modelmentioning

confidence: 98%

Finite difference and lead field methods in designing implantable ECG monitor

2006

View full text Add to dashboard Cite

To minimize time-consuming and expensive in vitro and in vivo testing, information regarding the effects of implantation and the implants on measurements should be available during the designing of active implantable devices measuring bioelectric signals such as electrocardiograms (ECG). Modeling offers a fairly inexpensive and effective means of studying and demonstrating the effects of implantation on ECG measurements prior to any in vivo tests, and can thus provide the designer with valuable information. Finite difference model (FDM) and lead field approaches offer straightforward and effective modeling methods supporting the designing of active implantable ECG devices. The present study demonstrates such methods in developing and studying ECG implants. They were applied in demonstrating the effects of implant dimensions and of electrode implantation on the measurement sensitivity of the ECG device. The results of the simulations indicated that the interelectrode distance is the factor of the implant design determining the lead sensitivity. Other parameters related implant dimensions and shape have minor effect on the morphology of the ECG or on the average sensitivity of the measurement. This is shown for example when the interelectrode distance was reduced to 1/3 of original the average lead sensitivity decreased by 69.1% while larger relative changes in other dimensions produced clearly smaller changes. It was also observed here that implanting the electrodes deeper under the skin has major effects on the local sensitivities in heart muscle and thus affect to the morphology of the ECG. The study indicated also that non-conducting medium (i.e. implant insulated body) between the electrodes increases the sensitivity on heart muscle compared to cases where only electrodes are implanted.

show abstract

Section: Finite Difference Modelmentioning

confidence: 98%

Finite difference and lead field methods in designing implantable ECG monitor

2006

View full text Add to dashboard Cite

show abstract

“…in the inverse procedure a large number of forward calculations need to be evaluated, it would be too time-consuming to solve the forward problem for each dipole source position and orientation utilising successive overrelaxation. We take advantage of the reciprocity theorem to reduce the number of iteratively solved forward calculations (RUSH and DRISCOL[, 1969;MALMIVUO and PLONSEY, 1995;LAARNE et al, 1995;VANRUMSTE et al, 1998). The accuracy of the numerical method was evaluated in VANRUMSTE et al (1998).…”

Section: Finite Difference Methods and Reciproci Omentioning

confidence: 99%

Dipole location errors in electroencephalogram source analysis due to volume conductor model errors

Vanrumste

Hoey

Walle

et al. 2000

Med. Biol. Eng. Comput.

View full text Add to dashboard Cite

An examination is made of dipole location errors in electroencephalogram (EEG) source analysis, due to not incorporating the ventricular system (VS), omitting a hole in the skull and underestimating skull conductivity. The simulations are performed for a large number of test dipoles in 3D using the finite difference method. The maximum dipole location error encountered, utilising 27 and 53 electrodes is 7.6 mm and 6.1 mm, respectively when omitting the VS, 5.6 mm and 5.2 mm, respectively when neglecting the hole in the skull, and 33.4 mm and 28.0 mm, respectively when underestimating skull conductivity. The largest location errors due to neglecting the VS can be found in the vicinity of the VS. The largest location errors due to omitting a hole can be found in the vicinity of the hole. At these positions the fitted dipoles are found close to the hole. When skull conductivity is underestimated, the dipole is fitted close to the skull-brain border in a radial direction for all test dipoles. It was found that the location errors due to underestimating skull conductivity are typically higher than those found due to neglecting the VS or neglecting a hole in the skull.

show abstract

“…2B. The electric sources and fields of the EEG can be studied using accurate individual resistive anatomical models (9,17,18). Representation of these results requires advanced displaying methods.…”

Section: Methodsmentioning

confidence: 99%