EIT in Breast Cancer Imaging: Application to Patient-Specific Forward Model

Electrical Impedance Tomography is a relatively new technique whereby objects or phantoms can be imaged through injecting the containing medium with electrical currents along its periphery. EIT, in its various forms, has been applied to several areas in medical diagnosis and monitoring, including the measurements of breast tissues impedance. Studies have shown that cancerous tissues have electrical properties that are significantly different from their normal surroundings. X-ray mammography has been set as the primary method of breast cancer screening. However, EIT currently still falls within a category of techniques which are used as adjunct methods to X-ray mammography, in this category are Ultrasound and MRI. These techniques are used as follow-up on the results of mammography. the problem of estimating the inner conductivities from surface measurements is an ill-conditioned problem in which some regularization strategies have to take place in order to obtain a stable and accurate solution by incorporating some prior information into the solution. the purpose of this paper is to demonstrate the application of EIT on a patient-specific model for the single- and multiple-electrodes models and discuss the pros and cons of adding dimensionality to the model with respect to the image reconstruction process. This comparison will be based on the RMSE (Root mean square error) and Pearson's correlation criteria which were not used previously in this respect.

I. Introduction

Breast cancer continues to be a leading cause of death in western countries and yet the most common cancer in women worldwide, comprising 16% of all female cancers. It is estimated that 519,000 women died in 2004 due to breast cancer (WHO Global Burden of Disease, 2004). Breast cancer survival rates vary greatly worldwide, ranging from 80% or over in North America, Sweden and Japan to around 60% in middle-income countries and below 40% in low-income countries (Coleman et al., 2008). The prognostic for women diagnosed with the disease is greatly influenced by the stage at which it is discovered. Long term survival is significantly improved for women found with small tumors in the early stages of development.