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

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 reconstructedwire phantom image, we achieved 60- and 70-mu maxial 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.

Automated summary

The study investigates the potential of phased-array IVUS utilizing coded excitation (CE) for improving penetration depth and image signal-to-noise ratio. By characterizing the performance of a new experimental broadband capacitive micromachined ultrasound transducer (CMUT) array, the research showed promising results in improving image quality in medical imaging.