Dielectric Properties of Fluid-Saturated Bone

Chakkalakal, Dennis A.; Johnson, Marvin W.; Harper, Richard A.; Katz, J. Lawrence

doi:10.1109/tbme.1980.326713

Cited by 73 publications

(24 citation statements)

References 11 publications

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“…For instance, in a thicker skull in which the thickness of the (higher conductivity) spongiform layer is large relative to the thicknesses of the compacta layers, total skull conductivity can be expected to be higher than that of a thinner skull (Law, 1993). On the other hand, skull conductivity has been shown to be dependent on electrolyte content and on bone density (Akhtari et al, 2000; Chakkalakal et al, 1980). Thus, skull conductivity may be more strongly dependent on its material properties than on geometric details.…”

Section: Discussionmentioning

confidence: 99%

Simultaneous head tissue conductivity and EEG source location estimation

Acar

Makeig

2016

NeuroImage

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Accurate electroencephalographic (EEG) source localization requires an electrical head model incorporating accurate geometries and conductivity values for the major head tissues. While consistent conductivity values have been reported for scalp, brain, and cerebrospinal fluid, measured brain-to-skull conductivity ratio (BSCR) estimates have varied between 8 and 80, likely reflecting both inter-subject and measurement method differences. In simulations, mis-estimation of skull conductivity can produce source localization errors as large as 3 cm. Here, we describe an iterative gradient-based approach to Simultaneous tissue Conductivity And source Location Estimation (SCALE). The scalp projection maps used by SCALE are obtained from near-dipolar effective EEG sources found by adequate independent component analysis (ICA) decomposition of sufficient high-density EEG data. We applied SCALE to simulated scalp projections of 15 cm2-scale cortical patch sources in an MR image-based electrical head model with simulated BSCR of 30. Initialized either with a BSCR of 80 or 20, SCALE estimated BSCR as 32.6. In Adaptive Mixture ICA (AMICA) decompositions of (45-min, 128-channel) EEG data from two young adults we identified sets of 13 independent components having near-dipolar scalp maps compatible with a single cortical source patch. Again initialized with either BSCR 80 or 25, SCALE gave BSCR estimates of 34 and 54 for the two subjects respectively. The ability to accurately estimate skull conductivity non-invasively from any well-recorded EEG data in combination with a stable and non-invasively acquired MR imaging-derived electrical head model could remove a critical barrier to using EEG as a sub-cm2-scale accurate 3-D functional cortical imaging modality.

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Section: Discussionmentioning

confidence: 99%

Simultaneous head tissue conductivity and EEG source location estimation

Acar

Makeig

2016

NeuroImage

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“…Thus understanding electrical properties of bone tissue and their relations to underlying physical and physiological phenomena is crucial for full comprehension and proper modeling of the mechanisms appearing in impedance spectroscopy, tomography or during stimulated osteogenesis [15]. Electrical properties of both compact [16][17][18][19] and trabecular bone [20][21][22] have been investigated. The trabecular bone has been reported to be electrically anisotropic [15,23] and the electrical properties to be different in dry [15] and wet [16,24,25] tissue.…”

Section: Introductionmentioning

confidence: 99%

“…Electrical properties of both compact [16][17][18][19] and trabecular bone [20][21][22] have been investigated. The trabecular bone has been reported to be electrically anisotropic [15,23] and the electrical properties to be different in dry [15] and wet [16,24,25] tissue. Furthermore, electrical properties are significantly related to bone mechanical properties [26,27], structure [19,28,29], as well as to dry and ash densities [30].…”

Section: Introductionmentioning

confidence: 99%

Effect of human trabecular bone composition on its electrical properties

Sierpowska

Lammi

Hakulinen

et al. 2007

Medical Engineering & Physics

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“…Chakkalakal, Johnson, Harper, and Katz (1980) measured dielectric relaxation of bovine femoral cortical bone in vitro saturated with physiological solution (0.9% NaCl solution). They showed that the dielectric behavior of fluid saturated compact bone is determined mostly by fluid-filled pores.…”

Section: Introductionmentioning

confidence: 99%