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

低频（< 20mhz）超声（LFUS）是诊断医学中最常见的成像方式之一，主要是因为它安全、可靠和实时。相比之下，高频（bbb20 mhz）超声（HFUS）成像是一项相对较新的技术，与低频系统相比，其图像分辨率要高一个数量级。尽管分辨率有所提高，但HFUS系统并未在临床实践中常规使用。阻碍其应用的主要障碍是，直到最近，这些系统都是基于单元件几何聚焦换能器，产生的图像景深有限，帧率较慢。在LFUS系统中，通过用换能器阵列和电子波束形成器取代单元件换能器，大大提高了帧率和景深。这使得电子聚焦在组织内的大范围深度和提高帧率。因此，人们对开发基于阵列的HFUS系统非常感兴趣。不幸的是，制造高频阵列及其相关的波束形成器是非常困难的。特别是，为了在这些非常短的波长上产生紧密准直的超声波光束，需要具有微观尺寸的阵列元件。此外，高频率要求电子波束形成器的数字采样分辨率和并行信号处理速度大大提高。2009年，世界上第一个商用的HFUS阵列系统发布。然而，该系统的阵列设计用于局部应用，其中相对较大的孔径和封装无关紧要。我们正在开发一种更小的内窥镜形式的HFUS阵列，专门用于通过耳道对耳朵的表面下结构进行成像。该提案为实时50 MHz数字波束形成器寻求基础设施资金。这将使我们能够使用定制的50 MHz阵列内窥镜生成实时图像，我们目前正在使用我们最近建立的微型制造设备开发内窥镜。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至关重要。

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.