Electrode guarding in electrical impedance measurements of physiological systems--a crituque

Electro-impedance mammograms for automatic breast cancer screening: First insights on Mexican patients

Breast cancer is a very important health concern around the world. Early detection of such a disease increases the chances of survival. Among the available screening tools, there is the Electro-Impedance Mammography (EIM), which is a novel and less invasive method that captures the potential difference stored in breast tissues under the assumption that electrical properties among normal and pathologically altered tissues are different. In this paper, we address breast cancer detection as a multi-class problem aiming to determine the corresponding label in terms of the Breast Imaging Electrical Impedance classification system, the standard used by physicians for interpreting an EIM mammogram. For experimental purposes, for the first time in the literature, we took advantage of a dataset comprising EIM of Mexican patients. Aiming to establish a baseline for this task, traditional supervised learning methods were used together with two different feature extraction techniques: raw pixel data and transfer learning. Besides, data augmentation was exploited for compensating data imbalance. Different experimental settings were evaluated reaching classification rates over 0.85 in F-score. KNN emerges as a very promising classifier for addressing this task. The obtained results allow us to validate the usefulness of traditional methods for classifying electro-impedance mammograms.

Sensitivity distribution simulations of surface electrode configurations for electrical impedance myography

INTRODUCTION

Surface-based electrical impedance myography (EIM) is sensitive to muscle condition in neuromuscular disorders. However, the specific contribution of muscle to the obtained EIM values is unknown.

METHODS

We combined theory and the finite element method to calculate the electrical current distribution in a 3-dimensional model using different electrode array designs and subcutaneous fat thicknesses (SFTs). Through a sensitivity analysis, we decoupled the contribution of muscle from other surrounding tissues in the measured surface impedance values.

RESULTS

The contribution of muscle to surface EIM values varied greatly depending on the electrode array size and the SFT. For example, the contribution of muscle with 6-mm SFT was 8% for a small array compared with 32% for a large array.

CONCLUSIONS

The approach presented can be employed to inform the design of robust EIM electrode configurations that maximize the contribution of muscle across the disease and injury spectrum. Muscle Nerve 56: 887-895, 2017.

Bipolar resistivity profiling of 3D tissue culture

We describe a new low-cost technique for continuous monitoring of the thickness of biofilms and tissue cultures, and we demonstrate the advantage of using electrodes of different dimensions to probe different depths of a sample. We have used electric impedance spectroscopy to monitor keratinocyte stem cells (YF29) growing on an array of Ti/Pt coplanar microelectrodes. The thickness of the sample was reconstructed by fitting the measurements to theoretical curves. We have developed an algorithm for the rapid calculation of the resistance through a multilayered sample. This algorithm is based on conformal mapping and the serial partial capacitance technique. The validity of the technique was tested by measuring the sedimentation rate of an alumina powder. Sample thicknesses between 10 and 80 microm could be measured with a resolution of a few microns using the device.

An appraisal of techniques for studying cerebral circulation in the newborn. Report of a mini-symposium held in September 1982

The study of cerebral circulation in ill pre-term infants is important both to improve our understanding of the physiological aspects of cerebral blood flow control, and to provide further insight into the aetiology of intracranial intra-ventricular haemorrhage. Progress in this field has been hampered by the absence of measurement techniques which must be safe and clinically applicable whilst at the same time providing results with sufficient quality for the confident development of hypotheses. The symposium was held in order to evaluate critically the measurement techniques which might be considered for use in the sick, human newborn infant.