3-D ultrasound imaging using a forward-looking CMUT ring array for intravascular/intracardiac applications

Abstract—Forward-viewing ring arrays can enable new applications in intravascular and intracardiac ultrasound. This work presents compelling, full-synthetic, phased-array volumetric images from a forward-viewing capacitive micro-machined ultrasonic transducer (CMUT) ring array wire bonded to a custom integrated circuit front end. The CMUT ring array has a diameter of 2 mm and 64 elements each 100 m 100 m in size. In conventional mode, echo signals received from a plane reflector at 5 mm had 70% fractional bandwidth around a center frequency of 8.3 MHz. In collapse mode, 69 % fractional bandwidth is measured around 19 MHz. Measured signal-to-noise ratio (SNR) of the echo averaged 16 times was 29 dB for conventional oper-ation and 35 dB for collapse mode. B-scans were generated of a target consisting of steel wires 0.3 mm in diameter to determine resolution performance. The 6 dB axial and lat-eral resolutions for the B-scan of the wire target are 189 m and 0.112 radians for 8 MHz, and 78 m and 0.051 radi-ans for 19 MHz. A reduced firing set suitable for real-time, intravascular applications was generated and shown to pro-duce acceptable images. Rendered three-dimensional (3-D) images of a Palmaz-Schatz stent also are shown, demon-strating that the imaging quality is sufficient for practical applications. I