Harmonic intravascular ultrasound imaging with a dual-frequency catheter

Recent studies have shown the feasibility of tissue and contrast harmonic imaging with a prototype nonlinear intravascular ultrasound (IVUS) system using a conventional single-element rotating IVUS catheter. In this study, a dual-frequency transducer element was mounted in an IVUS catheter and its second harmonic imaging performance was investigated and compared with that of a conventional IVUS catheter. Hydrophone measurements showed a transmit efficiency improvement of >6 dB for the dual-frequency catheter at 20 MHz. In vitro phantom experiments showed a signal-to noise ratio improvement of >5 dB in second harmonic mode at 40 MHz (H40) with the dual-frequency catheter, when using equal transmit voltage for both catheters. Finally, in vivo experiments were conducted and showed image improvement in H40 acquisitions with respect to the conventional IVUS catheter. (E-mail: m.frijlink@erasmusmc.nl)