title: Phantom evaluation of stacked-type dual-frequency 1-3 composite transducers: A feasibility study on intracavitary acoustic angiography.
abstract: In this paper, we present phantom evaluation results of a stacked-type dual-frequency 1-3 piezoelectric composite transducer as a feasibility study for intracavitary acoustic angiography. Our previous design (6.5/30 MHz PMN-PT single crystal transducer) for intravascular contrast ultrasound imaging exhibited a contrast-to-tissue ratio (CTR) of 12 dB with a penetration depth of 2.5 mm. For improved penetration depth (>3 mm) and comparable contrast-to-tissue ratio (>12 dB), we evaluated a lower frequency 2/14 MHz PZT 1-3 composite transducer. Superharmonic imaging performance of this transducer and a detailed characterization of key parameters for acoustic angiography are presented. The 2/14 MHz arrangement demonstrated a -6 dB fractional bandwidth of 56.5% for the transmitter and 41.8% for the receiver, and produced sufficient peak-negative pressures (>1.5 MPa) at 2 MHz to induce a strong nonlinear harmonic response from microbubble contrast agents. In an in-vitro contrast ultrasound study using a tissue mimicking phantom and 200 μm cellulose microvessels, higher harmonic microbubble responses, from the 5th through the 7th harmonics, were detected with a signal-to-noise ratio of 16 dB. The microvessels were resolved in a two-dimensional image with a -6dB axial resolution of 615 μm (5.5 times the wavelength of 14 MHz waves) and a contrast-to-tissue ratio of 16 dB. This feasibility study, including detailed explanation of phantom evaluation and characterization procedures for key parameters, will be useful for the development of future dual-frequency array transducers for intracavitary acoustic angiography.
authors.affiliation: Department of Mechanical & Aerospace Engineering, The North Carolina State University, Raleigh, NC 27695, USA.
authors.forename: Jinwook
authors.initials: J
authors.lastname: Kim
authors.affiliation: Department of Mechanical & Aerospace Engineering, The North Carolina State University, Raleigh, NC 27695, USA.
authors.forename: Sibo
authors.initials: S
authors.lastname: Li
authors.affiliation: Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Chapel Hill, NC 27599, USA.
authors.forename: Sandeep
authors.initials: S
authors.lastname: Kasoji
authors.affiliation: Joint Department of Biomedical Engineering, University of North Carolina and North Carolina State University, Chapel Hill, NC 27599, USA.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Dayton
authors.affiliation: Department of Mechanical & Aerospace Engineering, The North Carolina State University, Raleigh, NC 27695, USA. Electronic address: xjiang5@ncsu.edu.
authors.forename: Xiaoning
authors.initials: X
authors.lastname: Jiang
mesh_terms: D000162:Acoustics; D000792:Angiography / Q000295:instrumentation*; D003287:Contrast Media; D004867:Equipment Design; D005240:Feasibility Studies; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D045423:Microbubbles; D019047:Phantoms, Imaging; D059629:Signal-To-Noise Ratio; D014159:Transducers; D018084:Ultrasonography, Interventional / Q000295:instrumentation* / Q000379:methods
chemical_list: D003287:Contrast Media
keywords: 1–3 composite transducer; Dual-frequency transducer; Intracavitary probe; Superharmonic imaging; Ultrasound contrast agents