Development of a Miniature Real-Time High-Resolution Endoscopic 3D Ultrasound System

拟议的研究计划侧重于开发用于高分辨率成像应用的高频超声技术。高频超声是一项相对较新的技术，它使用微制造成像探头，其分辨率比目前用于诊断成像的传统超声系统高一个数量级。具体而言，主要目标是开发小型化（<3mm）成像内窥镜以及所有相关的电子硬件和软件，使该技术能够用作从体内可视化组织的工具，而不是目前仅限于外部局部应用的等效技术。这种高分辨率内窥镜的潜在应用包括腹腔镜、听觉、心内、神经成像等。在传统的脉冲回波超声中，成像系统的分辨率与换能器产生的超声脉冲的频率成正比，然而，更高的频率（更高的分辨率）是以较低的穿透深度为代价的。传统的低频大穿透超声成像系统是基于压电传感器阵列的。通过使用由许多单独寻址的压电元件组成的换能器阵列，可以通过电子方式改变孔径的有效曲率，从而获得更好的图像质量。阵列的使用也使得可以在更大的一组元素（线性阵列）上复用一组元素的子集，或者从一组固定的元素（相控阵）上引导超声波波束到不同的角度。由于相控阵有能力引导聚焦的超声光束，它们可以用更小的尺寸产生大视场的图像，这使得它们适合内窥镜应用，只要探头的直径不受电子互连封装的影响。这个正在进行的研究项目最近解决了一些与开发微型高频相控阵内窥镜相关的挑战。这些挑战包括阵列元件的微制造，以及将这些元件以小型化的形式连接到电缆系统。虽然先前开发的内窥镜是目前世界上最先进的超声成像阵列之一，但在将其作为一种有用的诊断技术实现之前，仍有大量的研究问题和挑战需要解决。拟议的研究计划将通过设计、制造和实现第一种电子硬件和软件来建立这些先前的发展，以允许成像内窥镜生成实时高分辨率图像。该研究项目还将开发新型的二维微加工成像阵列，不仅可以产生高质量的图像，还可以从相同小型化形状的内窥镜中产生实时3D体积。目前还没有其他成像技术能够将如此高的分辨率与微型前视内窥镜的外形因素结合起来。这项技术在几个不同的医学领域彻底改变诊断的潜力是非常真实的。这不仅对加拿大医疗保健系统（以及国际）有很大的好处，可以改善诊断和手术指导，而且这项技术也代表了有价值的知识产权，在地方和国家范围内都有许多商业化的机会。该研究项目通过将高科技微加工训练与传统生物医学工程方法的独特结合，对研究生来说也是一个非常有价值的培训项目。

The proposed research program is focused on developing high-frequency ultrasound technologies for use in high-resolution imaging applications. High-frequency ultrasound is a relatively new technology that uses micro-fabricated imaging probes that are capable of an order of magnitude higher resolution than conventional ultrasound systems currently used in diagnostic imaging. Specifically, the primary objective is to develop miniaturized (<3mm) imaging endoscopes and all of the associated electronic hardware and software that will enable this technology to be used as a tool for visualizing tissues from within the body, as opposed to the current equivalent technology that is limited to external topical applications. Potential applications of such a high resolution endoscope include laparoscopic, auditory, intracardiac, neural imaging, and many more. In conventional pulse-echo ultrasound, the resolution of the imaging system is proportional to the frequency of the ultrasound pulse generated by the transducer, however, higher frequency (higher resolution) comes at the price of lower penetration depth. Conventional low frequency large penetration ultrasound imaging systems are based on piezoelectric transducer arrays. By using a transducer array, which is made of many individually addressed piezoelectric elements, the effective curvature of the aperture can be changed electronically, resulting in a much better image quality. Use of an array also makes it possible to either multiplex a subset of elements across a much larger set of elements (linear array), or to steer the ultrasound beam to different angles from a fixed set of elements (phased array). Because phased arrays have the ability to steer the focused ultrasound beam, they can generate images with a large field-of-view from a much smaller form factor, and this makes them desirable for endoscopic applications as long as the diameter of the probe is not dominated by packaging of the electrical interconnects.This on-going research program has recently solved some of the challenges associated with developing miniature high frequency phased array endoscopes. These challenges include the micro-fabrication of the array elements and interconnecting these to a cabling system in a miniaturized form factor. Although the previously developed endoscope currently represents one of the most advanced ultrasound imaging arrays in the world, there are still a large number of research questions and challenges that need to be addressed before it can be realized as a useful diagnostic technology. The proposed research program will build upon these previous developments by designing, fabricating, and implementing first of a kind electronic hardware and software to allow the imaging endoscope to generate real-time high resolution images. The research program will also develop novel 2D micro-fabricated imaging arrays that will not only produce images of superior quality, but also real-time 3D volumes from an endoscope of identical miniaturized form factor. Currently no other imaging technology exists that combines such high resolution, with the miniature forward looking endoscopic form factor. The potential for this technology to revolutionize diagnostics in several different fields of medicine is very real. Not only could this be of great benefit to the Canadian health care system (and international) in terms of improving diagnostics and surgical guidance, but the technology also represents valuable IP that has many commercialization opportunities on both a local and national scale. This research program is also a very valuable training program for graduate students through a unique combination of high tech micro-fabrication training with conventional biomedical engineering methods.