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 1.2mm diameter. We characterized the array performance for CE imaging and showed that the -6 dB device bandwidth at 30 V DC biasing is 25 MHz with 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 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 μm and 70 μm axial resolution using the short pulse and coded signal, respectively and gained 8 dB in SNR for coded excitation. Our developed system shows 20 frames per second, pixel-based beam-formed, real-time IVUS images.

Acoustics, Atherosclerotic plaque, Bandwidth, CMUT, Coded Excitation, Coronary Heart Disease, Frequency modulation, Imaging, IVUS, Mismatched Filtering, Pixel-based beam-forming, Signal to noise ratio, Transducers, Ultrasonic imaging,
I E E E Transactions on Ultrasonics, Ferroelectrics and Frequency Control
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Department of Biomedical Engineering

Pakdaman Zangabad, R, Bosch, J.G, Mastik, F, Beurskens, R, Henneken, V.A. (Vincent A.), Weekamp, J.W. (Johannes W.), … van Soest, G. (2021). Real-Time Coded Excitation Imaging Using a CMUT-based Side Looking Array for Intravascular Ultrasound. I E E E Transactions on Ultrasonics, Ferroelectrics and Frequency Control. doi:10.1109/TUFFC.2021.3054971