Very-High-Frequency Ultrasound Imaging With Coded Signals and Annular Arrays

描述(申请人提供)：甚高频超声提供分辨率优于100微米的非侵入性诊断成像。甚高频超声(VHFU)对皮肤、眼部、胃肠道粘膜和动脉斑块等浅表组织的成像具有重要意义。VHFU的两个主要限制因素是小的景深和频率相关的衰减。较小的景深只允许在焦点周围较小的轴向范围内获得高分辨率图像，而频率相关的衰减限制了VHFU在浅层成像中的应用。我们建议开发信号处理和VHFU成像策略，以缓解这两个限制因素。具体地说，我们将结合编码激励算法和环形阵列技术。VHFU编码信号的具体设计将提高信噪比(SNR)，从而增加VHFU波的穿透深度。VHFU环形阵列允许动态聚焦，可以显著增加景深，而不需要线性阵列中所需的大量元件；这极大地简化了电子设备，并促进了临床扫描的实施。超声中的编码激励从来没有在非常高的频率下被研究过，也没有被与最先进的环形阵列相结合。我们计划扩展这些方法，以获得有关组织微结构的定量信息。这种定量的超声信息将导致一种新的方法来区分疾病和正常组织，并监测疾病的进展或消退。虽然这个项目中将要开发的技术和方法对浅层组织成像具有普遍的适用性，但这个研究计划将在眼科学的背景下开发。这项拟议的研究可以显著改善对青光眼、玻璃体膜、出血、脉络膜肿瘤以及视网膜和脉络膜脱离等眼科病理的评估，这些疾病对常规高频超声成像具有挑战性。如果成功，这项拟议的研究还将导致其他临床专业诊断超声的显著改进。它将允许获得分辨率高、景深更大和穿透深度更深的医学图像，并带来改进诊断成像和疾病管理的新能力。

DESCRIPTION (provided by applicant): Ultrasound at very-high-frequency provides non-invasive diagnostic imaging with resolution better than 100 um. Very-high-frequency ultrasound (VHFU) is of great interest for imaging superficial tissues, such as skin, eye, gastrointestinal mucosa, and arterial plaque. The two main limiting factors for VHFU are the small depth of field and the frequency-dependent attenuation. The small depth of field allows fine-resolution images over only a small axial range about the focus, and the frequency-dependent attenuation limits application of VHFU to shallow imaging. We propose to develop signal-processing and VHFU imaging strategies that will mitigate these two limiting factors. Specifically, we will combine coded-excitation algorithms with annular-array technologies. The specific design of coded signals for VHFU will increase signal-to-noise ratio (SNR), which will permit an increased depth of penetration of VHFU waves. VHFU annular arrays allow dynamic focusing that can significantly increase the depth of field without requiring the large number of elements needed in linear arrays; this greatly simplifies electronics and facilitates implementation for clinical scanning. Coded excitation in ultrasound has never been investigated at very high- frequencies nor has it been combined with state-of-the-art annular arrays. We plan to extend the methodologies to obtain quantitative information about tissue microstructures. This quantitative ultrasound information will lead to a new means of distinguishing diseased from normal tissue and of monitoring disease progression or regression. While the technology and methodology to be developed in this project have general applicability for imaging superficial tissues, this research program will be developed in the context of ophthalmology. The proposed research can lead to significant improvement in evaluation of ophthalmic pathologies such as glaucoma, vitreous membranes, hemorrhage, choroidal tumors, and retinal and choroidal detachment that are challenging to image with conventional high-frequency ultrasound. If successful, the proposed research also will lead to significant improvement of diagnostic ultrasound in other clinical specialties. It will allow obtaining medical images with exquisite resolution, increased depth of field and a greater depth of penetration, and lead to new capabilities for improved diagnostic imaging and disease management.