IMT

Various organs and tissues in a human body possess different electrical properties. For instance, it is a well-known fact that many tumours, in particular malignant breast tumours, feature electrical conductivity (ability to conduct electrical current), which differs considerably from the electrical conductivity of surrounding healthy tissues. The MEM makes it possible to obtain the picture of biological tissues electrical conductivity distribution in the breast in its transverse sections and locate such tumours in the obtained images.

The multifrequency electrical impedance mammograph (MEM) principle of operation is based on the method of electrical impedance tomography (EIT). The present device has come to replace the previously developed single-frequency device MEIK. Scientific research in the field of electrical impedance tomography has been developing since the middle of 1980s. The method enables the examiner, utilizing a full  (in mathematical sense) set of electrical measurements, performed with the help of a multielectrode system, to reconstruct spatial distribution of electrical properties inside an object. The process of reconstruction is carried out through solving of the so-called inverse problem for the equation of electric field in inhomogeneous medium. A group of Russian scientists, comprising researchers from the Institute of Radio-engineering and Electronics of the Russian Academy of Sciences, is one of the world leader in the field of the EIT. Below comes a list of some publications of the abovementioned researchers in scientific journals: A.V. Korjenevsky, et al "Electrical impedance computerized tomograph for medical applications", Instruments and Experimental Techniques, v. 40, No 3, p. 415-421 , 1997; V. Cherepenin, et al "A 3D electrical impedance tomography (EIT) system for breast cancer detection", Physiol. Meas., v. 22(1), p. 9-18, 2001; V. Cherepenin, et al, "Three-dimensional EIT imaging of breast tissues: system design and clinical testing", IEEE Trans. Medical Imaging, v. 21(6), p. 662-667, 2002; Korjenevsky A.V. et al, "Electrical impedance tomography system for 3D imaging of the breast tissues", Biomeditsinskie tekhnologii i radioelektronika, N 8, p. 5-10, 2003; Trokhanova O.V., Okhapkin M.B. and Korjenevsky A.V. "Dual-frequency electrical impedance mammography for the diagnosis of non-malignant breast disease", Physiol. Meas., v. 29, p. S331-S344, 2008.

The device comprises a measuring block with a built-in microprocessor control system, which houses a matrix with 256 electrodes. Two remote electrodes, which are positioned on a patients arm, are connected via a cable to the measuring block. During the scanning process the device, utilizing one out of 256 electrodes of the matrix sequentially injects into the patient’s body weak alternative electric current and registers corresponding distributions of potentials on its surfaces using the rest of the electrodes. The obtained data are used then for reconstruction of the electrical impedance images with the help of the mathematical algorithms utilizing a personal computer to which the device is connected vie the USB port. The utilized algorithm allows to reconstruct three-dimensional distribution of electrical conductivity (in the form of tomographic cross-sections of various depths) and to obtain highly detailed images. The utilized measuring scheme and the algorithm of image reconstruction make imaging results practically insusceptible to the skin surface condition. The MEM makes it possible to carry out examination with various frequencies, which in some cases enhances precision of diagnostics since depending on the tissues status, their electrical properties correlate differently with frequencies.

The mammograph is intended for application in specialized departments of hospitals and clinics of various institutions of public health. Electrical impedance mammography brings new possibilities into diagnostics of oncological as well non-oncological diseases of breast. Compared with the single-frequency electrical impedance mammography, multi-frequency mammography allows not only to diagnose the disease, but to define its form. For example, it is possible to differentiate a cystic mastopathy from an acyslic one, thus, segregating a risk group of patients with possible development of breast cancer for a closer examination and supervision. Visual changes in the tomograms are confirmed by quantitative characteristics of electrical conductivity, which rules out the elements of subjectivity in evaluation and establishing a diagnosis. Safety of the electrical impedance mammography method makes it possible to use it for screening and examination of young women. Details...