New Ultrasound Device May Aid in Detecting Risk for Heart Attack, Stroke

来自北卡罗来纳州立大学和北卡罗来纳大学教堂山分校的研究人员开发了一种超声设备，可以帮助识别动脉斑块，这些牙菌斑有脱离并引起心脏病发作或中风的高风险。

At issue is the plaque that builds up in arteries as we age. Some types of plaque are deemed “vulnerable,” meaning that they are more likely to detach from the artery wall and cause heart attack or stroke.

“Existing state-of-the-art technologies are capable of determining if plaque is present in the arteries, but can’t tell whether it’s vulnerable. And that makes it difficult to assess a patient’s risk,” says Dr. Paul Dayton, co-author of a paper on the new device and professor in the joint biomedical engineering department at NC State and Chapel Hill. “Our goal was to develop something that could effectively identify which plaques are vulnerable.”

There are two ultrasound techniques that can help identify vulnerable plaques, but both depend on the use of contrast agents called “microbubbles.”

第一种技术是识别动脉中的“ Vasa vasorum”。这些是经常浸入动脉斑块的小血管的簇，被认为是斑块很脆弱的指标。当将微泡注入动脉中时，它们会跟随血液的流动。如果存在瓦萨·巴萨鲁姆（Vasa Bateorum），则微泡也将流过这些血管，从而有效地在超声图像上突出显示它们。

The second technique is called molecular imaging, and relies on the use of “targeted” microbubbles. These microbubbles attach themselves to specific molecules that are more likely to be found in vulnerable plaques, making the plaques stand out on ultrasound images.

“问题在于，现有的血管内超声技术在检测对比剂方面没有很好的工作，”北卡罗来纳州机械和航空工程副教授江·江博士说，生物医学工程和共同教授的辅助教授纸。

“So we’ve developed a dual-frequency intravascular ultrasound transducer which transmits and receives acoustic signals,” Jiang says. “Operating on two frequencies allows us to do everything the existing intravascular ultrasound devices can do, but also makes it much easier for us to detect the contrast agents – or microbubbles – used for molecular imaging and vasa vasorum detection.”

The prototype device has performed well in laboratory testing, but the researchers say they are continuing to optimize the technology. They hope to launch pre-clinical studies in the near future.

该论文“用于对比度增强的声学血管造影和分子成像的血管内双频传感器的初步工程设计”超声波，铁电和频率控制的IEEE交易。该论文的主要作者是MA Jianguo MA，机械工程博士学位。北卡罗来纳州的学生。该论文由博士Heath Martin合着。联合生物医学工程计划的学生。

The research was supported by the National Institutes of Health, under grant 1R01EB015508.

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编辑报告s:The study abstract follows.

“血管内双频传感器的初步工程设计，用于对比增强声学血管造影和分子成像”

Authors：北卡罗来纳州立大学的江瓜和江江；Heath Martin和Paul A. Dayton，北卡罗来纳州立大学和北卡罗来纳大学教堂山分校

Published: May 2014,超声波，铁电和频率控制的IEEE交易

Abstract:Current intravascular ultrasound (IVUS) probes are not optimized for contrast detection due to 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 mm2), 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 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 ?m diameter micro-tube were clearly detected with a signal-to-noise ratio higher than 12 dB. The 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.