A real-time electronic beamformer for high-resolution ultrasound imaging of the Cochlea

低频(&lt；20 MHz)超声(LFUS)是诊断医学中最常见的成像手段之一，主要是因为它安全、可靠和实时。相比之下，高频(&gt；20 MHz)超声(HFUS)成像是一项相对较新的技术，与低频系统相比，图像分辨率高一个数量级。尽管分辨率有所提高，但高频超声系统并未常规用于临床实践。阻碍它们被采用的主要障碍是，直到最近，这些系统都是基于单一元件的几何聚焦换能器，产生的图像景深有限，帧速率慢。在LFUS系统中，通过用换能器阵列和电子波束形成器取代单一单元换能器，实现了帧速率和景深的显著改善。这允许在组织内的大范围深度进行电子聚焦，并提高了帧速率。因此，为高频超声开发基于阵列的系统引起了极大的兴趣。不幸的是，制造高频阵列及其相关的波束形成器是极其困难的。特别是，为了在这些非常短的波长上产生紧密准直的超声束，需要具有微观尺寸的阵列元件。此外，高频信号对电子波束形成器的数字采样分辨率和并行信号处理速度提出了更高的要求。2009年，世界上第一个商用的基于HFUS阵列的系统发布。然而，该系统的阵列是为局部应用而设计的，在这种应用中，相对较大的孔和包装并不重要。我们正在开发一种更小的内窥镜形式的高频超声阵列，专门用于通过耳道成像耳朵的亚表面结构。该提案寻求为实时50 MHz数字波束形成器提供基础设施资金。这将允许我们使用定制的50 MHz阵列内窥镜生成实时图像，该内窥镜是我们目前正在使用我们最近建立的微制造设施开发的。使用多普勒测速仪的实时成像能力对于进一步了解内耳动力学是必不可少的。

Low-frequency (< 20 MHz) ultrasound (LFUS) is one of the most common imaging modalities in diagnostic medicine, primarily because it is safe, reliable, and real-time. In contrast, high-frequency (>20MHz) ultrasound (HFUS) imaging is a relatively new technique, with an order of magnitude better image resolution compared to low-frequency systems. Despite the improved resolution, HFUS systems are not routinely used in clinical practice. The main barrier preventing their adoption is that until recently, these systems were based on single-element geometrically focused transducers that produced images with a limited depth-of-field and slow frame-rate. In LFUS systems, drastic improvements in both frame-rate and depth-of-field have been achieved by replacing the single-element transducer with a transducer array and an electronic beamformer. This allows electronic focusing at a wide range of depths within the tissue and increased frame-rates. Consequently, there has been a great deal of interest in developing array-based systems for HFUS. Unfortunately, fabricating high-frequency arrays and their associated beamformers is extremely difficult. In particular, to produce a tightly collimated ultrasound beam at these very short wavelengths, array elements with microscopic dimensions are required. In addition, the high frequencies require that the digital sampling resolution of the electronic beamformer and speed of parallel signal processing be greatly increased. In 2009, the world's first commercially available HFUS array-based system was released. The arrays for this system, however, are designed for use in topical applications in which relatively large apertures and packaging are of no concern. We are developing a much smaller HFUS array in an endoscopic form factor, specifically for imaging sub-surface structures of the ear via the ear canal. This proposal seeks infrastructure funding for a real-time 50 MHz digital beamformer. This will allow us to generate real-time images using the custom 50 MHz array endoscopes that we are currently developing using our recently established micro-fabrication facility. Real-time imaging capabilities with Doppler velocimetry are essential to furthering our understanding of inner-ear dynamics.