A DUAL FREQUENCY IVUS TRANSDUCER WITH A LATERAL MODE TRANSMITTER FOR CONTRAST ENHANCED INTRAVASCULAR ULTRASOUND IMAGING

摘要

Recent studies suggest that dual frequency intravascular ultrasound (IVUS) transducers are promising in contrast ultrasound for molecular imaging or vasa vasorum (VV) assessment to identify vulnerable plaques. Low frequency (1-3 MHz) acoustic waves are widely used for contrast imaging because it can excite microbubbles more effectively. However, conventional thickness mode 1-3 MHz transducers are not suitable for IVUS since bulky transducer size is not permitted in fine IVUS catheters used for coronary interventions (approx. 3-French). In this paper, a dual frequency (2.25 MHz/30 MHz) IVUS transducer with a lateral mode transmitter (2.25 MHz) and a thickness mode high frequency receiver (30 MHz) was designed, fabricated and characterized. In contrast detection tests, superharmonic microbubble responses flown through a 200 μm diameter tube was successfully detected with a contrast to noise ratio (CNR) of 13 dB and an axial resolution (-6 dB) of 0.1 μs (150 μm). The results showed that this dual frequency FVUS transducer with a lateral mode transmitter can be used to detect super-harmonic signal (12th to 15th harmonic) ideal for superharmonic imaging of microvascular structures.