Real-Time Coded Excitation Imaging Using a CMUT-Based Side Looking Array for Intravascular Ultrasound

• Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control ferroelectrics, and frequency control, 2021-06, Vol.68 (6), p.2048-2058
• Main Authors: Zangabad, Reza Pakdaman, Bosch, Johan G., Mastik, Frits, Beurskens, Robert H. S. H., Henneken, Vincent A., Weekamp, Johannes W., van der Steen, Antonius F. W., van Soest, Gijs
• Format: Article
• Language: English
• Subjects: Acoustics; Arrays; Atherosclerosis; Atherosclerotic plaque; Attenuation; Bandwidth; Broadband; capacitive micromachined ultrasound transducer (CMUT); coded excitation (CE); coronary heart disease; Diameters; Excitation; Frequency modulation; Image quality; Image reconstruction; Imaging; intravascular ultrasound (IVUS); Micromachining; mismatched filtering; Penetration depth; pixel-based beam-forming; Quality assessment; Real time; Short pulses; Signal to noise ratio; Stents; Transducers; Ultrasonic imaging; Ultrasound; Wire
• ISSN: 0885-3010; 1525-8955
• DOI: 10.1109/TUFFC.2021.3054971

Intravascular ultrasound (IVUS) is a well-established diagnostic method that provides images of the vessel wall and atherosclerotic plaques. We investigate the potential for phased-array IVUS utilizing coded excitation (CE) for improving the penetration depth and image signal-to-noise ratio (SNR). It is realized on a new experimental broadband capacitive micromachined ultrasound transducer (CMUT) array, operated in collapse mode, with 96 elements placed at the circumference of a catheter tip with a 1.2- {mm} diameter. We characterized the array performance for CE imaging and showed that the −6-dB device bandwidth at a 30-V dc biasing is 25 MHz with a 20-MHz center frequency, with a transmit sensitivity of 37 kPa/V at that frequency. We designed a linear frequency modulation code to improve penetration depth by compensating for high-frequency attenuation while preserving resolution by a mismatched filter reconstruction. We imaged a wire phantom and a human coronary artery plaque. By assessing the image quality of the reconstructed wire phantom image, we achieved 60- and 70- \mu{\mathrm {m}} axial resolutions using the short pulse and coded signal, respectively, and gained 8 dB in SNR for CE. Our developed system shows 20-frames/s, pixel-based beam-formed, real-time IVUS images.