Quantification of intraventricular hemorrhage with electrical impedance tomography using a spherical model

Tang, Tong; Sadleir, Rosalind

doi:10.1088/0967-3334/32/7/s06

Cited by 10 publications

(12 citation statements)

References 25 publications

(37 reference statements)

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“…The use of bioelectrical impedance measurements to detect water content and edema in the body was suggested already half a century ago [34]–[36]. Bioelectric measurements have evolved into an imaging technology known as Electrical Impedance Tomography (EIT) that uses arrays of contact electrodes to inject sub-sensory currents in the body and measure voltage to produce a map of electric impedance of tissue for use in various medical imaging applications, including detection of edema [37]–[44]. Bioelectrical measurements by electro-magnetic induction with non-contact electrical coils are considered a valuable alternative to contact electrode measurement [45]–[56].…”

Section: Discussionmentioning

confidence: 99%

Volumetric Electromagnetic Phase-Shift Spectroscopy of Brain Edema and Hematoma

et al. 2013

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Motivated by the need of poor and rural Mexico, where the population has limited access to advanced medical technology and services, we have developed a new paradigm for medical diagnostic based on the technology of “Volumetric Electromagnetic Phase Shift Spectroscopy” (VEPS), as an inexpensive partial substitute to medical imaging. VEPS, can detect changes in tissue properties inside the body through non-contact, multi-frequency electromagnetic measurements from the exterior of the body, and thereby provide rapid and inexpensive diagnostics in a way that is amenable for use in economically disadvantaged parts of the world. We describe the technology and report results from a limited pilot study with 46 healthy volunteers and eight patients with CT radiology confirmed brain edema and brain hematoma. Data analysis with a non-parametric statistical Mann-Whitney U test, shows that in the frequency range of from 26 MHz to 39 MHz, VEPS can distinguish non-invasively and without contact, with a statistical significance of p<0.05, between healthy subjects and those with a medical conditions in the brain. In the frequency range of between 153 MHz to 166 MHz it can distinguish with a statistical significance of p<0.05 between subjects with brain edema and those with a hematoma in the brain. A classifier build from measurements in these two frequency ranges can provide instantaneous diagnostic of the medical condition of the brain of a patient, from a single set of measurements. While this is a small-scale pilot study, it illustrates the potential of VEPS to change the paradigm of medical diagnostic of brain injury through a VEPS classifier-based technology. Obviously substantially larger-scale studies are needed to verify and expand on the findings in this small pilot study.

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Section: Discussionmentioning

confidence: 99%

Volumetric Electromagnetic Phase-Shift Spectroscopy of Brain Edema and Hematoma

et al. 2013

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“…TES is actively studied as an emerging therapeutic tool for treatment of depression [11], epilepsy [12], and other neurological disorders [13]. Electrical head models are also important in EIT applications for detection of intracranial bleeding or ischemia in stroke or traumatic brain injury [14], [15].…”

Section: Introductionmentioning

confidence: 99%

Skull Modeling Effects in Conductivity Estimates Using Parametric Electrical Impedance Tomography

Fernandez-Corazza

Turovets

Luu

et al. 2018

IEEE Trans. Biomed. Eng.

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Abstract-Objective: To estimate scalp, skull, compact bone and marrow bone electrical conductivity values based on Electrical Impedance Tomography (EIT) measurements, and to determine the influence of skull modeling details on the estimates. Methods: We collected EIT data with 62 current injection pairs and built five 6-8 million finite element (FE) head models with different grades of skull simplifications for four subjects, including three whose head models serve as Atlas in the scientific literature and in commercial equipment (Colin27 and EGI's Geosource atlases). We estimated electrical conductivity of the scalp, skull, marrow bone and compact bone tissues for each current injection pair, each model, and each subject. We also provide subject specific conductivity estimates for widely used Atlas head models.

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“…In previous papers (Sadleir and Tang 2009, Sadleir et al 2009, Tang et al 2010, Tang and Sadleir 2010, 2011) we described promising results in numerical simulations and phantom experiments. We found that an 16-electrode layout based on the electroencephalograph (EEG) 10–20 layout, combined with a measurement strategy that involved applying a sequence of current patterns with all return paths over the anterior fontanel (the ‘Cz pattern’) was superior to other patterns considered.…”

Section: Introductionmentioning

confidence: 82%

“…The sensitivity matrix may be computed from a finite element model of the imaged domain (Sadleir and Tang 2009). We found that reliable representations of introduced anomalies were produced when the head was modeled as a homogeneous sphere (Tang and Sadleir 2011), and this model was used as the sensitivity matrix in the in vivo reconstructions presented here. Reconstruction can then be achieved by pseudo-inversion of (1).…”

Section: Methodsmentioning

confidence: 99%

In vivoquantification of intraventricular hemorrhage in a neonatal piglet model using an EEG-layout based electrical impedance tomography array

et al. 2016

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Intraventricular hemorrhage (IVH) is a common occurrence in the days immediately after premature birth. It has been correlated with outcomes such as periventricular leukomalacia (PVL), cerebral palsy and developmental delay. The causes and evolution of IVH are unclear; it has been associated with fluctuations in blood pressure, damage to the subventricular zone and seizures. At present, ultrasound is the most commonly used method for detection of IVH, but is used retrospectively. Without the presence of adequate therapies to avert IVH, the use of a continuous monitoring technique may be somewhat moot. While treatments to mitigate the damage caused by IVH are still under development, the principal benefit of a continuous monitoring technique will be in investigations into the etiology of IVH, and its associations with periventricular injury and blood pressure fluctuations. Electrical impedance tomography (EIT) is potentially of use in this context as accumulating blood displaces higher conductivity cerebrospinal fluid (CSF) in the ventricles. We devised an electrode array and EIT measurement strategy that performed well in detection of simulated ventricular blood in computer models and phantom studies. In this study we describe results of pilot in vivo experiments on neonatal piglets, and show that EIT has high sensitivity and specificity to small quantities of blood (<1 ml) introduced into the ventricle. EIT images were processed to an index representing the quantity of accumulated blood (the ‘quantity index’, QI). We found that QI values were linearly related to fluid quantity, and that the slope of the curve was consistent between measurements on different subjects. Linear discriminant analysis showed a false positive rate of 0%, and receiver operator characteristic analysis found area under curve values greater than 0.98 to administered volumes between 0.5, and 2.0 ml. We believe our study indicates that this method may be well suited to quantitative monitoring of IVH in newborns, simultaneously or interleaved with electroencephalograph assessments.

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Quantification of intraventricular hemorrhage with electrical impedance tomography using a spherical model

Cited by 10 publications

References 25 publications

Volumetric Electromagnetic Phase-Shift Spectroscopy of Brain Edema and Hematoma

Volumetric Electromagnetic Phase-Shift Spectroscopy of Brain Edema and Hematoma

Skull Modeling Effects in Conductivity Estimates Using Parametric Electrical Impedance Tomography

In vivoquantification of intraventricular hemorrhage in a neonatal piglet model using an EEG-layout based electrical impedance tomography array

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