Constrained MRI Impedance Imaging
Abstract
An approach for imaging electric tissue properties in vivo is proposed. The technique relies upon the integration of MRI data with electrical potential measurements made over the surface of the patient. Through a technique referred to as constrained electric impedance tomography, the conductivity of specific regions identified in MRI data can be calculated. This work is a numerical simulation of the physics and mathematics of this concept. A two-dimensional simulation of a simple structure containing three-regions of varying electrical conductivity was generated and a finite-element model of electrical current propagation created. By arranging 24 electrodes around the object and numerically applying a voltage between a pair of them, the voltages between other pairs of electrodes were calculated using the finite-element model. This was repeated by numerically applying a voltage between other electrode pairs. These simulated voltage data were then used in conjunction with the known spatial distribution of object components to solve for their unknown electrical conductivity. An iterative nonlinear optimization technique was used to find the electrical conductivity distribution that minimizes the difference between the calculated voltages and the simulated input data. In the absence of noise, the reconstruction was excellent; however, it was shown to degrade in the presence of experimental noise. Nevertheless, the stability of the reconstruction suggested that the technique will be practical in an experimental system. We will continue these stimulations during the course of next year.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2002
- Accession Number
- ADA410234
Entities
People
- Donald B. Plewes