Quadruple ultrasound, photoacoustic, optical coherence, and fluorescence fusion imaging with a transparent ultrasound transducer

Abstract

Ultrasound and optical imagers are used widely in a variety of biological and medical applications. In particular, multimodal implementations combining light and sound have been actively investigated to improve imaging quality. However, the integration of optical sensors with opaque ultrasound transducers suffers from low signal-to-noise ratios, high complexity, and bulky form factors, significantly limiting its applications. Here, we demonstrate a quadruple fusion imaging system using a spherically focused transparent ultrasound transducer that enables seamless integration of ultrasound imaging with photoacoustic imaging, optical coherence tomography, and fluorescence imaging. As a first application, we comprehensively monitored multiparametric responses to chemical and suture injuries in rats’ eyes in vivo, such as corneal neovascularization, structural changes, cataracts, and inflammation. As a second application, we successfully performed multimodal imaging of tumors in vivo, visualizing melanomas without using labels and visualizing 4T1 mammary carcinomas using PEGylated gold nanorods. We strongly believe that the seamlessly integrated multimodal system can be used not only in ophthalmology and oncology but also in other healthcare applications with broad impact and interest.

High-resolution functional photoacoustic monitoring of vascular dynamics in human fingers

“…In addition to the applicability of the PAM itself, it can be easily combined with optical and ultrasonic technologies. The PAM study using a transparent ultrasonic transducer [ 64 ] is accelerating the combination of these technologies, which would help to diagnose PAD by providing multiple clinical information.…”

A Review of Transparent Sensors for Photoacoustic Imaging Applications

“…Furthermore, it has high electromechanical coupling, a high longitudinal sound speed, and a low dielectric constant [63], and thus is the prime choice for large-aperture, high-frequency, and highsensitivity optically transparent sensors. In 2014, Brodie et al introduced a sensor for US particle manipulation [28] 2b,e [32,60]. Epoxy was used for the acoustic lens and backing layer material for both sensors.…”

“…Optics-based US sensors mainly include Fabry-Perot (FP) etalons (FP) [17,18], micro-ring resonators (MRRs) [19][20][21][22], and grating-based sensors [23][24][25]. Transparent piezoelectric-based US sensors use piezoelectric materials that have sufficient optical transmittance, such as polyvinylidene fluoride (PVDF) polymer films [26,27] and lithium niobite (LN) single crystals [28][29][30][31][32]. Transparent CMUT is a new type of optically transparent US sensors, which has a limited operating frequency (less than 20 MHz) and is expensive due to the specialized MEMS fabrication techniques [33][34][35].…”

A photoacoustic finder fully integrated with a solid-state dye laser and transparent ultrasound transducer

“…The PAF fully integrates a custom transparent ultrasound transducer (TUT) and a solid-state dye laser handpiece. Unlike a conventional opaque UT, the TUT seamlessly enables coaxial optical and acoustic beams in a small form factor [ 42 ]. Our TUT is the first to use a single crystal lead magnesium niobate-lead titanate (PMN-PT), different from the TUT previously developed, which uses lithium niobate (LNO) [ 42 ] and polyvinylidene fluoride (PVDF) [ 43 ].…”

“…Unlike a conventional opaque UT, the TUT seamlessly enables coaxial optical and acoustic beams in a small form factor [ 42 ]. Our TUT is the first to use a single crystal lead magnesium niobate-lead titanate (PMN-PT), different from the TUT previously developed, which uses lithium niobate (LNO) [ 42 ] and polyvinylidene fluoride (PVDF) [ 43 ]. As a piezoelectric material, PMN-PT is especially suitable in the low-frequency range, due to its high electromechanical and dielectric properties compared to LNO and PVDF [ 44 ].…”