Textured-piezoelectric-ceramic-based focused intravascular ultrasonic transducer with improved image quality and uniformity

Abstract

Intravascular ultrasound (IVUS) imaging is a minimally invasive medical technology that plays a critical role in diagnosis, treatment guidance, and post-treatment assessment of coronary artery diseases. As a crucial component of the IVUS system, conventional IVUS transducers are designed to be planar and unfocused to adequately cover the region of interest. However, this design comes at the cost of spatial resolution. Here, we developed a high-performance focused IVUS transducer using Pb(In1/2Nb1/2)O3-Pb(Sc1/2Nb1/2)O3-PbTiO3 (PIN-PSN-PT) textured ceramics with both high electromechanical performance (thickness-mode electromechanical coupling factor kt: ∼60%) and high Curie temperature (TC: ∼250 °C). Benefiting from the relatively low clamped dielectric constant ( ϵ 33 S /ϵ0: ∼450) of PIN-PSN-PT-textured ceramics in contrast to currently used soft piezoelectric ceramics (>1000), we designed a relatively large aperture for the focused IVUS transducer, with a goal of enhancing lateral resolution across a larger depth of field, ranging from 1 to 5 mm. The developed focused IVUS transducer operates at 42 MHz with an −6 dB bandwidth of 72%, featuring a 0.6 × 0.6 mm2 aperture while maintaining an electrical impedance of approximately 40-60 Ω. The axial and lateral resolutions characterized by wire phantom imaging are 45 and 208 μm, respectively. The acoustic pressure generated by the focused IVUS transducer is 1.4 times higher than that of its planar counterpart. Ex vivo porcine coronary artery imaging demonstrates that our focused IVUS transducer offers improved image quality and uniformity for the visualization of intravascular structures. Our work shows great potential of PIN-PSN-PT-textured ceramics for creating high-frequency miniaturized focused transducers.