Electromagnetic tomography and tomographic angiography

A system for tomographic imaging of a dielectric object, comprising:

• an electromagnetic measurement system configured to acquire electromagnetic (EM) signals and digitize the EM signals,
• a cardiac activity recording system configured to acquire Electrocardiogram (ECG) signals and digitize the acquired ECG signals, and
• a computer system with a processor configured to
• synchronize the EM signals and the ECG signals,
• reconstruct images or movies of dielectric properties of the object or reconstruct images or movies of angio-dielectric properties of the object,
• process the reconstructed images or movies of the dielectric properties or the angio-dielectric properties,
• assess hypoxia and viability of biological tissues based on the post-processed images or movies, and
• for images ε(r)adupdated or movies ε(r, time)adupdated of angio-dielectric properties, the processor is further configured to:
• establish parameters and geometric configuration of the EM measurement system, including at least one of frequencies of the EM measurement system used, data acquisition time per acquisition frame, number of frames acquired, dielectric properties of media surrounding the object under the study within an imaging domain, number and position of transmitting antennas of the EM measurement system, and number and position of receiving antennas of the EM measurement system
• synchronize measurements of the EM signals and measurements of the ECG signals,
• choose a first and second phase of interest from a cardiac activity cycle,
• use raw data acquired from electromagnetic measurements system during the first phase,
• form a matrix of complex EM fields from N transceivers measured on M receivers according to (M*N matrix)−SijEXP-1, i=1,N;
• j=1,M;
• calibrate and form M*N matrix of calibrated SijEXP-1 based on first measurement phase data,
• use raw data acquired from electromagnetic measurements system during the second phase,
• form a matrix of complex EM fields from N transceivers measured on M receivers according to (M*N matrix)−SijEXP-2, i=1,N;
• j=1,M;
• calibrate and form M*N matrix of calibrated SijEXP-2 based on second measurement phase data,
• calculate perturbated M*N matrix of SijEXP 1/2=SijEXP-1+α(SijEXP-1−SijEXP-2)/|SijEXP-1|, wherein |SijEXP-1| is a norm of complex SijEXP-1 and α—is a parameter chosen by a trial method,
• iteratively reconstruct an image by using an initial distribution of dielectric properties ε1(r) at first iteration, wherein ε1(r)=ε0, where ε0 is known dielectric properties of outside of an object under the study and within the imaging domain,
• calculate EM field distribution from N (i=1,N) transceivers within the study domain Ei(εk(r)) and on M (j=1,M) receivers SijTHR at kth iteration (k=1,K),
• calculate of alteration Δ(ε(r)) using gradient or/and Newton type of methods in form of:
• a) for gradient Δ(ε(r))˜Σi,jN,M(Ei*(εk(r))×Ej*(εk(r))×(SijTHR−SijEXP 1/2)
• b) for Newton Δ(ε(r))˜inversion of the matrix Dij=(Ei*(εk(r))×Ej(εk(r));
• update a distribution of dielectric properties within the study domain at iteration kas ε(r)updated=εk-1(r)+Δ(ε(r)),
• determine if ε(r)updated satisfies a decision making criteria,
• in response to determining the decision criteria is satisfied displaying the reconstructed angio-dielectric image ε(r)updated and further process the image and store the image in a memory of the computer system,
• in response to determining the decision criteria is not satisfied, take the reconstructed angio-dielectric image ε(r)updated to the next iteration cycle,
• wherein the criteria is based on the satisfaction of the following inequation at iteration k:
• Σi,jN,M|(SijTHR_iter=k−SijEXP 1/2)|<β*Σi,jN,M|(SijTHR_iter=1−SijEXP 1/2)|, where |A| denotes a norm of complex A and β is a convergence accuracy parameter;
• provide multiple reconstructed images over time,
• provide input and control parameters and calculation flow control, and
• store electromagnetic measurements data, cardiac activity data and reconstructed angio-dielectric images ε(r)updated in a memory of the computer system.