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.2014.2977
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发表时间：
2014-05-01
影响因子：
3.6
通讯作者：
Jiang, Xiaoning
中科院分区：
文献类型：
--
作者：
Ma, Jianguo;Martin, K. Heath;Jiang, Xiaoning
目前的血管内超声（IVUS）探头由于其高频基模成像的设计而没有优化对比度检测。然而，经皮造影的数据表明，利用超声造影进行分子成像或血管评估来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 x 3mm） IVUS探头的设计、制造和特性，该探头优化用于高频对比度成像。该设计利用双频（6.5 MHz/30 MHz）换能器布置，在低频激发微气泡（接近其共振），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。该原型探头在6.5 MHz时能够产生大于1.2 MPa的稀有分数压力（机械指数：0.48）的非线性微泡响应，并且能够在宽带接收元件（中心频率：30 MHz， -6 db分数带宽：58.6%）下检测微泡响应。微气泡在直径200 μ m的微管中流动时产生的非线性超谐波被清晰地检测到，信噪比大于12 dB。初步的基频（30 MHz）幻象成像和双频超谐波成像结果表明，小孔径双频IVUS换能器有望用于对比度增强的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 x 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-mu m-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.