Emmanuel Marry | PubMed Health

PubMed2002

Electrical impedance endotomography.

In electrical impedance endotomography (EIE), the impedance measuring electrodes are placed at the centre of the region of interest instead of encircling it, as in usual electrical impedance tomography. EIE has been developed for prostate imaging. The developed mathematical model enables the derivation of analytical equations for electric potential, electric field and sensitivity. This paper focuses on the selection of an optimal current injection method capable of sensing distant points. Experimental measurements were carried out in vitro using an enlarged size, 50 mm diameter, 16-electrode mock-up probe placed in tap water. The collected data enabled the production of images of a circular insulating target, 10 mm in diameter located 100 mm from the axis of the probe. Future work includes extension of sensitivity range, improvement of image reconstruction, design of a multiple frequency hardware system and construction of a real-size, biocompatible impedance probe.

Computer Simulation↗

PubMed2002

Electrical impedance endo-tomography: imaging tissue from inside.

This paper describes a new method for scanning the conductivity of a tissue or an organ using a multielectrode impedance probe placed at the center of the region of interest. The long-term objective of the study is the evaluation, using an urethral impedance probe, of the lesion produced by ultrasound ablathermy of localized prostate cancer. The probe consists of electrodes placed at the surface of an insulating cylinder. The injected current passes around the cylinder and spreads in the medium surrounding the probe. This paper presents the theoretical bases of this method, the calculated sensitivity distributions of electrode configurations involving a pair of diametrically opposed electrodes and an application in vitro. The experimental set-up consisted of a water tank and a 16-electrode prototype probe 50 mm in diameter. Data sets were collected in the presence of conductivity perturbations produced by small size insulators or conductors and a 7.5% constant perturbation model. The presented images, although reconstructed using a simple retro-projection algorithm, demonstrate the feasibility of the method. Improvements in data collection and image reconstruction are possible.

Electric Impedance↗