Evaluation of the use of gold nanoparticle as contrast agent in electrical impedance imaging

Introduction: Electrical Impedance Tomography (EIT) is a real time and minimal invasive imaging modality for detection of lesions in tissues even when their structures show no changes. Early detection of lesion with EIT depends on difference between electrical impedance of targeted tissue and its surroundings. Therefore, finding a contrast agent for EIT that increase this difference could improve its ability for detection of lesions in early stages. In this study, ability of gold nanoparticles (GNP) to use as EIT contrast agent was investigated. Materials and Methods: Turkevich method was used to synthesis spherical shaped GNPs with the size of 20-25 nm. Characterization of size distribution and shape of synthesized NPs were determined by transmission electron microscopy (TEM). Two types of phantoms (chicken fat and muscle paste tissues) were prepared and their electrical impedance was measured by the 4- electrode method. These measurements were done with and without the presence of GNPs. Results: Results show that presence of gold nanoparticles leads to descending in electrical impedance of tissues. This effect is more significant in frequencies below 1 KHz and has different values for the fat and muscle tissues. Reduction in resistive impedance is about 40.24W and1.93W for fat and muscle tissues at frequency 1 KHz, respectively. Increase in EIT signal is a consequence of reduction in electrical impedance. Consequently, presence of GNPs enhances the EIT signal and this enhancement is different for the fat and muscle tissues. Conclusion: As signal enhancement is different for fat and muscle tissues, gold nanoparticles could be considered as EIT contrast agent to improve detection of abnormalities at early stages.