Stroke type differentiation using spectrally constrained multifrequency EIT: evaluation of feasibility in a realistic head model

Abstract

We investigate the application of multifrequency electrical impedance tomography (MFEIT) to imaging the brain in stroke patients. The use of MFEIT could enable early diagnosis and thrombolysis of ischaemic stroke, and therefore improve the outcome of treatment. Recent advances in the imaging methodology suggest that the use of spectral constraints could allow for the reconstruction of a one-shot image. We performed a simulation study to investigate the feasibility of imaging stroke in a head model with realistic conductivities. We introduced increasing levels of modelling errors to test the robustness of the method to the most common sources of artefact. We considered the case of errors in the electrode placement, spectral constraints, and contact impedance. The results indicate that errors in the position and shape of the electrodes can affect image quality, although our imaging method was successful in identifying tissues with sufficiently distinct spectra.

Intracranial hemorrhage alters scalp potential distribution in bioimpedance cerebral monitoring: Preliminary results from FEM simulation on a realistic head model and human subjects

“…Clinical results specifically confirmed that there exists a statistically significant (P < 0.05) larger potential difference in the scalp potential distribution of patients suffering acute/subacute ICH than the controls, which, unlike simulated results, can be measured relatively fast (<1 h). Although these results are in agreement with the results from other numerical and experimental studies, 32,34,35,37,45,46 unlike previous experimental studies using stroke lesions from the chronic phase, i.e., lesions over a month old, 34,35,45 we obtained EIS recordings from patients in the acute and subacute phases, i.e., lesions less than five days old, to demonstrate the potential usefulness of EBI for the prehospital triage of patients suffering acute/subacute brain injury.…”

“…31 In the past decade, EBI has also been proposed as a potentially useful technique for stroke detection. [32][33][34][35] With regard to ICH, in vitro EIS and EIT studies suggest that hemorrhage in the brain will modify the tissue's electrical properties, as the conductivity of blood is about three times greater than that of brain tissue. 36 Unfortunately, previous quantitative studies have been based on simple models and not supported by human bioimpedance measurements.…”

“…36 Unfortunately, previous quantitative studies have been based on simple models and not supported by human bioimpedance measurements. 32,37 Experimental studies have also been limited to the chronic phase of the stroke that is not relevant to the ultimate goal of bioimpedance technology for detecting acute/subacute ICH. 34 In this study, 3D accurate finite elements method (FEM) …”

Multifrequency electrical impedance tomography with total variation regularization

“…For example, WFD cannot reconstruct proper images if the area of perturbation is too large (Malone et al, 2014b). A method for performing MFEIT using Spectral Constraints (MFEITSC) was proposed by Malone et al, (2014bMalone et al, ( , 2014a. The inverse problem was modified by substituting the conductivity with the volume fraction of each tissue in each voxel, describing the physical distribution of tissues in the domain.…”

“…Four frequencies were adopted in the range of 20 Hz -3 kHz, as the conductivities in this range have the largest changes across frequencies (Malone et al, 2014a).…”