Dual-frequency IVUS transducer for acoustic radiation force impulse (ARFI) imaging

Coronary atherosclerotic disease is the major cause of mortality in the United States. Elasticity imaging techniques such as acoustic radiation force impulse (ARFI) imaging using intravascular ultrasound (IVUS) transducers can be used to characterize coronary plaque. Conventional IVUS transducers with frequencies of 20 MHz - 60 MHz are not optimized for high-voltage, long-duration pulses required for ARFI imaging. In this work, a dual-frequency IVUS transducer, consisting of a 6.5 MHz “pushing” element and a 26 MHz “tracking” element, was designed and fabricated for ARFI application. In ARFI testing with a 160 V, 1000-cycle burst excitation, a displacement of 12.3 μm was detected in a phantom with a Young´s modulus of 10 kPa at an axial depth of 3.5 mm. The result of this study suggests great potential of this dual-frequency IVUS transducer for intravascular ARFI imaging.