A 1 MHz Miniaturized Electrical Impedance Tomography System for Prostate Imaging

• Published in: IEEE transactions on biomedical circuits and systems Vol. 14; no. 4; pp. 787 - 799
• Main Authors: Rao, Arun, Murphy, Ethan K., Halter, Ryan J., Odame, Kofi M.
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.08.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Acidity; Amplification; application specific integrated circuit (ASIC); biomedical instrumentation; Biomedical measurement; Cancer screening; CMOS; Electric Impedance; Electrical impedance; Electrical impedance tomography (EIT); Electrodes; Equipment Design; Frequency ranges; hardware system design; Humans; Image reconstruction; imaging; Impedance; Instrumentation; Male; Medical imaging; Medical screening; Miniaturization - instrumentation; Phantoms, Imaging; Probes; Prostate - diagnostic imaging; Prostate cancer; prostate imaging; Prostatic Neoplasms - diagnostic imaging; Signal to noise ratio; Sodium channels; Tomography; Tomography - instrumentation; Tomography - methods; Variable gain; Voltage measurement
• ISSN: 1932-4545; 1940-9990
• DOI: 10.1109/TBCAS.2020.2994297

An ASIC for a high frequency electrical impedance tomography (EIT) imaging system for prostate cancer screening is presented. The ASIC enables a small form-factor architecture, which ensures high signal-to-noise ratio (SNR) at MHz frequencies. The 4-channel ASIC was designed and fabricated in a standard CMOS 0.18-<inline-formula><tex-math notation="LaTeX">\mu</tex-math></inline-formula>m technology and integrates a novel current driver for current stimulus, instrumentation amplifier to interface with the tissue, VGA to provide variable gain and ADC with SPI interface for digitization. A prototype miniaturized EIT system was built and it was evaluated using a model transrectal imaging probe immersed into a tank filled with saline and a metal inclusion that demonstrated the open-domain problem of imaging prostate cancer lesion. The system maintained an SNR between 66 and 76 dB over the frequency range of 500 Hz to 1 MHz. Also, it produced reconstructed EIT images that depicted the presence of the small metal inclusion that modeled a prostate cancer imaging application.