A preliminary engineering design of intravascular dual-frequency transducers for contrast-enhanced acoustic angiography and molecular imaging.
A preliminary engineering design of intravascular dual-frequency transducers for contrast-enhanced acoustic angiography and molecular imaging.
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DOI：
10.1109/tuffc.2014.6805699
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发表时间：
2014-05
期刊：
影响因子：
--
通讯作者：
Jiang X
中科院分区：
文献类型：
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作者：
Ma J;Martin K;Dayton PA;Jiang X
目前的血管内超声（IVUS）探头由于其设计用于高频基模成像，因此未针对对比度检测进行优化。然而，来自经皮造影成像的数据表明，利用造影超声进行分子成像或血管评估以进一步阐明动脉粥样硬化斑块沉积的可能性。本文介绍了一种小孔径（0.6 × 3 mm）血管内超声探头的设计、制造和表征，该探头针对高频对比成像进行了优化。该设计采用双频（6.5 MHz/30 MHz）换能器布置，用于在低频（接近其共振）激发微泡，并在高频检测其宽带谐波，最大限度地减少检测到的组织反向散射。原型探头能够在6.5 MHz下产生1.2 MPa以上的稀疏压力（机械指数：0.48）的非线性微泡响应，并且还能够使用宽带接收元件（中心频率：30 MHz，−6-dB分数带宽：58.6%）检测微泡响应。微气泡在200 μ m直径的微管道中流动时，可清晰地检测到非线性超谐波，信噪比大于12 dB。基频（30 MHz）下的初步体模成像和双频超谐波成像结果表明，小孔径双频IVUS探头有望用于对比增强IVUS成像。
Current intravascular ultrasound (IVUS) probes are not optimized for contrast detection because of their design for high-frequency fundamental-mode imaging. However, data from transcutaneous contrast imaging suggests the possibility of utilizing contrast ultrasound for molecular imaging or vasa vasorum assessment to further elucidate atherosclerotic plaque deposition. This paper presents the design, fabrication, and characterization of a small-aperture (0.6 × 3 mm) IVUS probe optimized for high-frequency contrast imaging. The design utilizes a dual-frequency (6.5 MHz/30 MHz) transducer arrangement for exciting microbubbles at low frequencies (near their resonance) and detecting their broadband harmonics at high frequencies, minimizing detected tissue backscatter. The prototype probe is able to generate nonlinear microbubble response with more than 1.2 MPa of rarefractional pressure (mechanical index: 0.48) at 6.5 MHz, and is also able to detect microbubble response with a broadband receiving element (center frequency: 30 MHz, −6-dB fractional bandwidth: 58.6%). Nonlinear super-harmonics from microbubbles flowing through a 200-μm-diameter micro-tube were clearly detected with a signal-to-noise ratio higher than 12 dB. Preliminary phantom imaging at the fundamental frequency (30 MHz) and dual-frequency super-harmonic imaging results suggest the promise of small aperture, dual-frequency IVUS transducers for contrast-enhanced IVUS imaging.