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Triple-Element Back-to-Back Transducer with 3D Printed Housing for Intravascular Ultrasound Imaging: A Feasibility Study

Intravascular ultrasound (IVUS) can provide a high-resolution cross-sectional image of the blood vessel to detect the plaque morphology. The resolution of the IVUS image is proportional to a center frequency, however, a penetration depth decreases accordingly. To compensate for this problem, in this study, we propose the triple-element IVUS transducer capable of selecting an operating frequency according to the desired imaging area. In the proposed transducer, three-piezoelectric layers of 10 MHz, 20 MHz, and 30 MHz are formed on the top and both sides of the cube-shaped acoustic stack. These active layers share a common backing layer connected to one co-axial cable and can be driven simultaneously. In order to facilitate the manufacture process of the proposed IVUS transducer, split-assembling fabrication technique and a 3D printed housing with patterned electrodes were employed. The design specifications of the transducer were determined based on finite element analysis (FEA) simulation, and the prototype transducer was fabricated for feasibility study. The successful operation of individual elements constituting the proposed transducer was verified through B-mode imaging experiments using wire and tissue-mimicking phantoms. Subsequently, as a result of performing frequency compounding by combining two and three fundamental images, it was confirmed that the CNR (Contrast-to-Noise) value was improved by about 44%-77%. Therefore, the proposed IVUS transducer is expected to be one of the useful methods for diagnosing vascular diseases.