The system comprising an internal unit (10) comprising two arrays of N transmitter and N receiver antennas (11R, 11T) for transmitting a microwave signal(s) to one or more body tissues of a patient and for detecting a scattered microwave signal(s) by said one or more body tissues; feeding and multiplexing means (12) in connection with said N transmitter and N receiver antennas (11T, 11R) and with an external computing unit (20) configured to receive said scattered microwave signal(s) and convert it/them into an image, wherein the feeding and multiplexing means (12) provide, under the control of a controller (21) of the external computing unit (20), a continuous sequential selection of different pairs of transmitter and receiver antennas (11T, 11R) to perform the transmission of the microwave signal(s) and the detection of the scattered microwave signal(s).