To test the feasibility of performing intravascular ultrasound imaging using ultrasound transducers mounted inside the balloon of a dilatation catheter, we evaluated a prototype catheter which consisted of 8 miniature 20MHz ultrasound transducers mounted radially around the tip of a 4.5F balloon dilatation catheter and excited by small wires running the 150 cm length of the catheter through the inflation lumen. The transducer array was located at the catheter tip midway within the length of a 3.0cm long polyethylene balloon and was 2.3 mm in external diameter. Imaging occurred perpendicular top the long-axis of the catheter through the balloon in a radial direction. Accuracy of measuring arterial internal diameter was assessed in vitro by sequentially exciting industrial transducers while the catheter tip was located within pig aortic segments which varied from 4 to 16mm in internal diameter. Ultrasound aortic diameter measurements were correlated with actual aortic diameters. (r=0.98 and SEE=0.65mm). We conclude that it is feasible to measure arterial diameter through a dilatation balloon using a fixed array of miniature ultrasound transducers. Further development is ongoing to miniaturize the array so that intracoronary imaging will be possible in humans.
Mallory J, Gregory KW, Morcos NC, Griffith J, Henry W., Evaluation of a balloon angioplasty intravascular ultrasonic imaging device. Circulation (Suppl.II) 76:II-371, 1987.