Electrical Impedance Tomography (EIT)

EIT is the technique enabling to visualize spatial distribution of electrical impedance (or conductivity) inside the object, such as human body. The device uses voltage measurements on the object's surface when the electric current passes through the volume, as initial data for the image reconstruction. A suitable operation of the device requires both fast and effective reconstruction algorithms and high accuracy of electrical measurements. As the measurements in electrical impedance tomography can be made rather fast, high processing speed of the facilities enables to visualize many processes (such as heart pulsation) in real time. We are developing both the measurement equipment for EIT and methods of inverse problem solving.

BELT BASED EIT SYSTEM FOR 2D CROSS-SECTIONAL IMAGING
The experimental electrical impedance tomograph and software are created, which are used now in medical researches, mainly in pulmonology. Main advantages of the developed approach are: the possibility of absolute conductivity visualization in a human body cross-section, high measurement rate up to 12 frames per second. As essential parts of the tomography system, there are the data processing system and database. According to the first clinical results, the new device is capable to diagnose number of pulmonary diseases including cancer, and therefore impedance tomography could substitute x-ray investigations in many cases as harmless and accessible method. The system is tested also currently as mean for lungs monitoring at premature babies. See the photos of EIT measuring equipment and reconstructed images of the human chest.

ON-LINE STATIC EIT RECONSTRUCTION SERVER AND GALLERY
Visualization of absolute conductivity distribution inside the body (i.e. real anatomy) is still intriguing problem in EIT. During a few years our research group develops fast and robust static EIT imaging method, which is used currently with the experimental EIT systems. We develop this server to enable researchers from EIT community to try our algorithms with the data collected by different instruments and to estimate advantages of static in vivo EIT imaging. Examples of static images reconstructed with this server are presented in the EIT gallery.

MEASURING SYSTEM AND RECONSTRUCTION ALGORITHM FOR 3D EIT STATIC IMAGING
The system enables to obtain images of the 3-D conductivity distribution in regions below the skin surface up to several centimeters deep. The 256-electrode measuring system and image reconstruction algorithm are used for breast tissues imaging and diagnostics, in particular, for malignant tumors detection. See the photo of the multifrequency electrical impedance mammograph MEM and examples of tomographic images obtained during clinical tests.

Magnetic Induction Tomography (MIT)

MIT unlike EIT doesn't requires electrical contacts with the body and uses interaction of oscillating magnetic field with conductive media. The field, which can be excited and registered by small coils arranged around the object, is perturbed by eddy currents in the object. The conductivity (and permittivity) can be reconstructed from the measurements of perturbed field outside the objects. We have developed theoretical base of induction tomography, reconstruction algorithm and forward problem solver for the simulation of measurements. Although the approximated equation for vector potential in case of MIT is very similar to the equation for scalar potential in case of EIT, there are important differences in solving corresponding inverse problems. The first experimental measuring system for MIT with 16 transmitting and receiving coils has been built and tested recently in the laboratory. First images are reconstructed successfully from the data measured on phantom with this system. Of course, the MIT approach can be used in many applications besides medicine due to contact-free operation and possibility to choose optimal frequency of magnetic field for given conductivity and size of the object under investigation.
See the illustrations of MIT basics, photo of the first measuring system and images reconstructed from the experimental data. The result of image reconstruction from the simulated data is also demonstrated.

Electric Field Tomography (EFT)

The EFT method exploits interaction of high-frequency electric field with inhomogeneous conductive medium without contact with the electrodes. Unlike an electrical impedance tomography no electric current is injected into the medium from the outside. The interaction is accompanied with high frequency redistribution of free charges inside the medium and leads to small and regular phase shifts of the field in the area surrounding an object. Such kind of phenomena is referred as the Maxwell-Wagner relaxation. Measuring the perturbations of the field using the set of electrodes placed around the object enables to reconstruct internal structure of the medium. Electric field of course can be used for imaging of dielectric (nonconducting) objects, this technique is known as electrical capacitance tomography (ECT). See the results of EFT imaging simulation.

References

• Trokhanova O V, Chijova Y A, Okhapkin M B, Korjenevsky A V and Tuykin T S "Possibilities of electrical impedance tomography in gynecology", Journal of Physics: Conference Series, v. 434, 012038, 2013
  
• V.A. Cherepenin, Y.V. Gulyaev, A.V. Korjenevsky, S.A. Sapetsky and T.S. Tuykin, "An electrical impedance tomography system for gynecological application GIT with a tiny electrode array", Physiol. Meas., v. 33, pp 849-862, 2012
• A.K. Babushkin., A.S. Bugaev, A.V. Vartanov, A.V. Korjenevsky, S.A. Sapetsky, T.S. Tuykin and V.A Cherepenin "Development of the methods and instruments of the magnetic induction tomography for investigation of the human brain and cognitive functions", Izvestia Rossiyskoy Akademii Nauk. Seria Fizicheskaya, v. 75, N 1, pp 144-148, 2011
  
• Yu.V. Gulyaev, A.V. Korjenevsky, T.S. Tuykin and V.A. Cherepenin "Vizualizing electrically conducting media by electric field tomography", Journal of Communication Technology and Electronics, v. 55, No 9, pp 1062-1069, 2010
• A.V. Korjenevsky and T.S. Tuykin, "Experimental demonstration of electric field tomography", Physiol. Meas., v. 31, pp S127-S134, 2010
• T. Tuykin and A. Korjenevsky "3D EFT imaging with planar electrode array: Numerical simulation", J. Phys.: Conf. Ser., v. 224, 012054, 2010
  
• S. Sapetsky, V. Cherepenin, A. Korjenevsky, V. Kornienko and A. Vartanov "Development of the system for visualization of electric conductivity distribution in human brain and its activity by the magnetic induction tomography (MIT) method", J. Phys.: Conf. Ser., v. 224, 012038, 2010
• A. Korjenevsky, V. Cherepenin, O. Trokhanova and T. Tuykin "Gynecologic electrical impedance tomograph", J. Phys.: Conf. Ser., v. 224, 012070, 2010
  
• A.V. Korjenevsky, T.S. Tuykin and V.A. Cherepenin "Imaging of conducting media by the electric field tomography method", Physics of wave phenomena, v. 18, pp 57-63, 2010
  
• O.V. Trokhanova, M.B. Okhapkin, A.V. Korjenevsky, V.N. Kornienko and V.A. Cherepenin "Diagnostic possibilities of the electrical impedance mammography method", Biomeditsinskaya Radioelektronika, No 2, pp 66-77, 2009
• A.V. Korjenevsky and T.S. Tuykin, "Phase measurement for electric field tomography", Physiol. Meas., v. 29, pp S151-S161, 2008
• O.V. Trokhanova, M.B. Okhapkin and A.V. Korjenevsky "Dual-frequency electrical impedance mammography for the diagnosis of non-malignant breast disease", Physiol. Meas., v. 29, pp S331-S344, 2008
• T. Tuykin and A. Korjenevsky, "Electric field tomography system with planar electrode array" IFMBE Proceedings, v. 17,  pp 201–204, 2007
• A.V. Korjenevsky and T.S. Tuykin, "Electric field tomography: setup for single-channel measurements", Physiol. Meas., v. 28, pp S279-S289, 2007
• A.V. Korjenevsky and T.S. Tuykin, "Single-channel measuring setup for experiments on electric field tomography", Biomeditsinskie tekhnologii i radioelektronika, N 1, pp 60-66, 2007
• A. Korjenevsky and T. Tuykin, "Experimental Setup for Single-Channel Electric Field Tomography Measurements", Proc. 7th Conf. Biomedical Applications of Electrical Impedance Tomography (Seoul, Korea), p 177, 2006
• A.V. Korjenevsky, "Electrical impedance tomography: research, medical applications and commercialization", Almanakh Klinicheskoy Meditsiny, v. 12, II Troitsk Conference "Medical Physics and Innovations in Medicine" (Troitsk, Russia), p. 58, 2006
• A.V. Korjenevsky, "Maxwell-Wagner relaxation in electrical imaging", Physiol. Meas., v. 26(2), pp S101-S110, 2005
• A.V. Korjenevsky, "Electric field tomography", Proc. XII Int. Conf. Electrical Bio-Impedance & V Electrical Impedance Tomography (Gdansk, Poland), pp 691-694, 2004
• S.A. Sapetsky and A.V. Korjenevsky, "Magnetic induction tomography: visualization of extensive objects", Proc. XII Int. Conf. Electrical Bio-Impedance & V Electrical Impedance Tomography (Gdansk, Poland), pp 695-698, 2004
• A.V. Korjenevsky, "Contactless tomography of conducting media by quasistatic alternative electric field", Radiotekhnika i Elektronika, v. 49, N 6, pp 761-766, 2004
• A.V. Korjenevsky, "Electric field tomography for contactless imaging of resistivity in biomedical applications", Physiol. Meas., v. 25(1), pp 391-401, 2004
• A.V. Korjenevsky, A.Yu. Karpov, V.N. Kornienko, Yu.S. Kultiasov and V.A. Cherepenin, "Electrical impedance tomography system for 3D imaging of breast tissues", Biomeditsinskie tekhnologii i radioelektronika, N 8, pp 5-10, 2003
• A.V. Korjenevsky, "Neural network algorithms for solving inverse problems in radio frequency tomography", Neyrokomp'utery: razrabotka i primemenie, N 9-10, pp 26-33,  2002
• V. Cherepenin, A. Karpov, A. Korjenevsky, V. Kornienko, Y. Kultiasov, M. Ochapkin, O. Trochanova and D. Meister, "Three-dimensional EIT imaging of breast tissues: system design and clinical testing", IEEE Trans. Medical Imaging, v. 21(6), pp 662-667, 2002
• V. Cherepenin, A. Karpov, A. Korjenevsky, V. Kornienko, Yu. Kultiasov, A. Mazaletskaya and D. Mazourov, "Preliminary static EIT images of the thorax in health and disease", Physiol. Meas., v. 23(1), pp 33-41, 2002
• A. Korjenevsky, "Solving inverse problems in electrical impedance and magnetic induction tomography by artificial neural networks" (in Russian), Journal of Radioelectronics, N 12 - December 2001, http://jre.cplire.ru/jre/dec01/index_e.html (www journal)
• A.V. Korjenevsky, V.A. Cherepenin and S.A. Sapetsky, "Magnetic induction tomography - new imaging method in biomedicine", Proc. 2nd World Congr. Industrial Process Tomography (Hannover), pp 240-246, 2001
• A.V. Korjenevsky, V.A. Cherepenin, A.Yu. Karpov, V.N. Kornienko and Yu.S. Kultiasov, "An electrical impedance tomography system for 3-D breast tissues imaging", Proc. XI Int. Conf. Electrical Bio-Impedance (Oslo), pp 403-407, 2001
• V. Bardin, V. Cherepenin, A. Karpov, A. Korjenevsky, V. Kornienko, Y. Kultiasov and V. Marushkov, "Static EIT-images of new-borns' lungs. Preliminary results", Proc. XI Int. Conf. Electrical Bio-Impedance (Oslo), pp 457-460, 2001
• O. Trokhanova, A. Karpov, V. Cherepenin, A. Korjenevsky, V. Kornienko, Y. Kultiasov and V. Marushkov, "Electro-impedance mammography testing at some physiological woman's periods", Proc. XI Int. Conf. Electrical Bio-Impedance (Oslo), pp 461-465, 2001
• V. Cherepenin, A. Karpov, A. Korjenevsky, V. Kornienko, A. Mazaletskaya, D Mazourov and D. Meister, "A 3D electrical impedance tomography (EIT) system for breast cancer detection", Physiol. Meas., v. 22(1), pp 9-18, 2001
• A. Karpov, A. Korjenevsky, D. Mazurov, V. Kornienko and A. Mazaletskaya, "3D Electrical Impedance Scanning of Breast Cancer", World Congr. Med. Phys. Biomed. Eng. (Chicago), 3 pp, CD-ROM, 2000
• D. Mazurov, A. Karpov,  V. Cherepenin, A. Korjenevsky, V. Kornienko, A. Mazaletskaya, "2D electrical impedance scanning of thorax cancer", 2nd EPSRC Engineering Network meeting Biomedical applications of EIT (London), 2000
• A. Korjenevsky, V. Cherepenin and S. Sapetsky, "Magnetic induction tomography: experimental realization", Physiol. Meas., v. 21(1), pp 89-94, 2000
• A.V. Korjenevsky, S.A. Sapetsky and V.A. Cherepenin, "Magnetic induction tomography: experimental implementation" (in Russian), Izvestiya Akademii Nauk, Seriya Fizicheskaya, v.63, No12, pp 2437-2441, 1999
• A.V. Korjenevsky, V.A. Cherepenin and S.A. Sapetsky, "Visualization of electrical impedance by magnetic induction tomography", Med. Biol. Eng. Comput., v. 37, Suppl. 2, Proc. Eur. Med. Biol. Eng. Conf. (Vienna), pp 154-155, 1999
• V.A. Cherepenin and A.V. Korjenevsky, "Numerical simulation of nonlinear impedance tomography", Med. Biol. Eng. Comput., v. 37, Suppl. 2, Proc. Eur. Med. Biol. Eng. Conf. (Vienna), p 152, 1999
• A.V. Korjenevsky and V.A. Cherepenin, "Progress in realization of magnetic induction tomography", Annals of the New York Academy of Sciences, v. 873, pp 346-352, 1999
• A.V. Korjenevsky and V.A. Cherepenin, "Magnetic induction tomography" (in Russian), Journal of Radioelectronics, N 1 - December 1998, http://jre.cplire.ru/jre/dec98/index_e.html (www journal)
• A.V. Korjenevsky and V.A. Cherepenin, "Measuring system for induction tomography", Proc. X Int. Conf. Electrical Bio-Impedance (Barcelona), pp 365-368, 1998
• V.A. Cherepenin and A.V. Korjenevsky, "Nonlinear impedance tomography", Proc. X Int. Conf. Electrical Bio-Impedance (Barcelona), pp 449-450, 1998
• A.V. Korjenevsky, V.A. Cherepenin, V.N. Kornienko and Yu.S. Kultiasov, "Electrical impedance tomography with non-adjacent current injection and back projection image reconstruction", Proc. X Int. Conf. Electrical Bio-Impedance (Barcelona), pp 451-453, 1998
• A.V. Korzhenevskii and V.A. Cherepenin, "Magnetic induction tomography", Journal of Communication Technology and Electronics, v. 42, No 4, pp 469-474 (translated from Russian "Radiotekhnika i Elektronika", v. 42, No 4, pp 506-512), 1997
• A.V. Korzhenevskii, V.N. Kornienko, M.Yu. Kul'tiasov, Yu.S. Kul'tiasov and V.A . Cherepenin, "Electrical impedance computerized tomograph for medical applications", Instruments and Experimental Techniques, v. 40, No 3, pp 415-421 (translated from Russian "Pribory i Tekhnika Experimenta", No 3, pp 133-140), 1997
• A. Korjenevsky and V. Cherepenin, "Induction tomography: theory, computer simulation and elements of measuring system", Med. Biol. Eng. Comp., v.35, suppl. part 1, World Congr. Medical Physics and Biomedical Engineering (Nice), p 330, 1997
• A.V. Korjenevsky, V.A. Cherepenin, L.V. Yasin, "Nonstationary radiative transport in highly scattering media simulated by the method of particles" (in Russian), Izvestiya Akademii Nauk, Seriya Fizicheskaya, v.61, No12, pp 2363-2369, 1997
• V.A. Cherepenin, A.V. Korjenevsky, V.N. Kornienko, Yu.S. Kultiasov and M.Yu. Kultiasov, "The electrical impedance tomograph: new capabilities", Proc. IX Int. Conf. Electrical Bio-Impedance (Heidelberg), pp 430-433, 1995
• A.V. Korjenevsky, "Reconstruction of absolute conductivity distribution in electrical impedance tomography", Proc. IX Int. Conf. Electrical Bio-Impedance (Heidelberg), pp 532-535, 1995

Contact:
Alexander Korjenevsky
E-mail:  korjenevsky@cplire.ru