Ultrasonic Imaging 2014, Vol. 36(3) 167–176 © The Author(s) 2014 Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/0161734614523738 ultrasonicimaging.sagepub.com Article Double Ring Array Catheter for In Vivo Real-Time 3D Ultrasound Stephen W. Smith 1 , Paul Gardea 2 , Vivek Patel 1 , Stephen J. Douglas 2 , and Patrick D. Wolf 1 Abstract We developed new forward-viewing matrix transducers consisting of double ring arrays of 118 total PZT elements integrated into catheters used to deploy medical interventional devices. Our goal is 3D ultrasound guidance of medical device implantation to reduce x-ray fluoroscopy exposure. The double ring arrays were fabricated on inner and outer custom polyimide flexible circuits with inter-element spacing of 0.20 mm and then wrapped around an 11 French (Fr) catheter to produce a 15 Fr catheter (outer diameter [O.D.]). We used a braided cabling technology to connect the elements to the Volumetrics Medical Imaging (VMI) real-time 3D ultrasound scanner. Transducer performance yielded an average -6 dB fractional bandwidth of 49% ± 11% centered at 4.4 MHz for 118 elements. Real-time 3D cardiac scans of the in vivo pig model yielded good image quality including en face views of the tricuspid valve and real-time 3D guidance of an endo-myocardial biopsy catheter introduced into the left ventricle. Keywords 2D array transducer, real-time 3D imaging, interventional devices, catheter, cardiac Introduction The long-term goal of this project is the development of integrated kits comprised of matrix transducers consisting of ring arrays with a central catheter lumen for real-time 3D ultrasound guidance of the deployment of interventional medical devices. Our purpose is to reduce x-ray fluoroscopy exposure to the patient and health care personnel during interventional device implantation. Previously, we developed side-viewing and forward-viewing lead zirconate tita- nate (PZT)-based matrix array catheter transducers 1,2 and endoscopes 3,4 for real-time in vivo 3D ultrasound imaging. More recently, we fabricated forward-viewing ring array catheters for 3D image guidance of interventional devices such as the vena cava filter and aortic aneurysm stent graft, 5 trans-apical heart valves, 6 and atrial septal occluders. 7 A forward-viewing ring array was originally described by Wang et al. 8 Other laboratories are developing forward-viewing capaci- tive micromachined ultrasonic transducers (CMUT) ring arrays for electrophysiological 1 Department of Biomedical Engineering, Duke University, Durham, NC, USA 2 Covarx Corporation, Apex, NC, USA Corresponding Author: Stephen W. Smith, Department of Biomedical Engineering, Duke University, Box 90281,Durham, NC 27708, USA. Email: ssmith@duke.edu 523738UIX XX X 10.1177/0161734614523738Ultrasonic ImagingSmith et al. research-article 2014