Active microwave tomographic imaging of isolated, perfused animal organs

Abstract

The relative transparency of biological materials to high-frequency electromagnetic waves has encouraged the development of new systems for imaging. This report describes experiments of microwave tomography conducted on a prototype. The object to be analyzed is submerged in water and is illuminated by a plane wave. The total electric field is analyzed by a microwave camera. The recorded data are then processed numerically in order to reconstruct the image that corresponds to the distribution of equivalent currents in a defined plane of a section. Experiments have been conducted on isolated kidneys with and without perfusion. The influence of the perfusing solution temperature has also been studied. These experiments show the potential of this system, especially through the correlation between microwave images and the biological structures. They also confirm previous results concerning spatial resolution and depth of exploration. Finally, the results demonstrate the influence of temperature and support the applicability of this imaging system in non-invasive thermometry, especially for clinical hyperthermia.

Advances in Electromagnetic Fields in Living Systems

“…The tremendous improvements in image quality and imaging time, during the past 20 years, suggest that the field of MRI still has an enormous potential for growth, especially in the measurement of tissue chemistry and function under normal or disease conditions. Several other tomographic techniques for tissue imaging are currently under investigation, which exploit the cost differential and at the same time, utilize the nonionizing and noninvasive advantages of electric and magnetic fields [Franchois, et al, 1998;Guerquin-Kern et al, 1985;Larsen and Jacobi, 1979;Meaney et al, 1996;Semenov et al, 1996Semenov et al, , 2002. Of late, a great deal of emphasis has been directed toward the area of breast cancer detection.…”

Planar microwave imaging camera for biomedical applications: Critical and prospective analysis of reconstruction algorithms

“…Preliminary evaluations have been performed on different sites with phantoms, isolated organs, or volunteers [e.g., Bolomey et al, 1983Bolomey et al, , 1987Guerquin-Kern et al, 1985;Gaboriaud et al, 1987]. They confirm the sensitivity of microwave images with respect to deep gradients in water content, temperature, blood flow rate, ..., through their influence on the complex permittivity of living tissues.…”