title: System Description and First Application of an FPGA-Based Simultaneous Multi-Frequency Electrical Impedance Tomography.
abstract: A new prototype of a multi-frequency electrical impedance tomography system is presented. The system uses a field-programmable gate array as a main controller and is configured to measure at different frequencies simultaneously through a composite waveform. Both real and imaginary components of the data are computed for each frequency and sent to the personal computer over an ethernet connection, where both time-difference imaging and frequency-difference imaging are reconstructed and visualized. The system has been tested for both time-difference and frequency-difference imaging for diverse sets of frequency pairs in a resistive/capacitive test unit and in self-experiments. To our knowledge, this is the first work that shows preliminary frequency-difference images of in-vivo experiments. Results of time-difference imaging were compared with simulation results and shown that the new prototype performs well at all frequencies in the tested range of 60 kHz-960 kHz. For frequency-difference images, further development of algorithms and an improved normalization process is required to correctly reconstruct and interpreted the resulting images.
authors.affiliation: Philips Chair for Medical Information Technology, RWTH Aachen University, Pauwelsstrasse 20, Aachen 52074, Germany. santos@hia.rwth-aachen.de.
authors.forename: Susana
authors.initials: S
authors.lastname: Aguiar Santos
authors.affiliation: Philips Chair for Medical Information Technology, RWTH Aachen University, Pauwelsstrasse 20, Aachen 52074, Germany. anne.robens@rwth-aachen.de.
authors.forename: Anne
authors.initials: A
authors.lastname: Robens
authors.affiliation: Philips Chair for Medical Information Technology, RWTH Aachen University, Pauwelsstrasse 20, Aachen 52074, Germany. boehm@hia.rwth-aachen.de.
authors.forename: Anna
authors.initials: A
authors.lastname: Boehm
authors.affiliation: Philips Chair for Medical Information Technology, RWTH Aachen University, Pauwelsstrasse 20, Aachen 52074, Germany. leonhardt@hia.rwth-aachen.de.
authors.forename: Steffen
authors.initials: S
authors.lastname: Leonhardt
authors.affiliation: Philips Chair for Medical Information Technology, RWTH Aachen University, Pauwelsstrasse 20, Aachen 52074, Germany. teichmann@hia.rwth-aachen.de.
authors.forename: Daniel
authors.initials: D
authors.lastname: Teichmann
keywords: FPGA; bioimpedance spectroscopy; complex impedance; electrical impedance tomography; frequency-difference imaging; multi-frequency; time-difference imaging