Performance improvements in a MF-EIT system for acute stroke: The UCL Mk2.5

A recently developed EITS system, the UCLH mk2.5 was tested on a resistor phantom and in linear time and frequency difference imaging of a cylindrical tank, 10cm diameter, filled with 0.1% saline, and 16 electrodes in a ring; the test object was a cylinder of banana, 2 cm long and 1 cm in diameter. Reproducible images with the same location as the test object were obtained with both methods. Noise over time was similar to previous measurements, 0.3%. The pixels located at the centre of the perturbation showed a similar spectrum to that measured with a HP impedance analyser with a centre frequency of 16 kHz compared to the 10 kHz with the HP impedance analyser. Overall, the system is much improved and is being evaluated in blood filled tanks, to represent more demanding multi-frequency test objects, with a view to use in human subjects. Keywords— multi-frequency electrical impedance tomography, EITS, acute stroke detection, calibration.