Real-Time Coded Excitation Imaging Using a CMUT-based Side Looking Array for Intravascular Ultrasound
Reza Pakdaman Zangabad (Erasmus MC)
Johan G. Bosch (Erasmus MC)
Frits Mastik (Erasmus MC)
Robert H.S.H. Beurskens (Erasmus MC)
Vincent A. Henneken (Philips Research)
Johannes W. Weekamp (Philips Research)
Antonius F.W. van der Steen (TU Delft - ImPhys/Medical Imaging, Erasmus MC, Philips Research)
Gijs van Soest (Erasmus MC)
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Abstract
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.
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