Advanced Polymeric Tissue-Mimicking Materials and Phantoms for Evaluation of Multispectral Photoacoustic Imaging Systems

超声是成像疾病的有力工具，包括癌症、骨科疾病和心脏功能。超声波的一个限制是，它的目标区域与背景组织之间的对比度较低。因此，人们对一种称为光声成像的特殊超声进行了广泛的研究。光声成像利用光在感兴趣的区域产生声音。这增加了对比度。不幸的是，光声超声尚未被批准在人体中广泛使用。这可能部分是由于缺乏标准化设备和方法来验证光声成像所需的新型成像设备。因此，这项提议的工作将创造出具有已知光学和声学特性的专门塑料物体，适合于光声成像设备的校准和标准化。该提案结合了学术界和食品和药物管理局的专业知识，以创建对仪器制造商和医生有用的测试对象和方法。由此产生的测试对象将提高如何最好地制造光声成像仪器的知识，并可能简化该设备的监管批准。反过来，这将增加患者获得这一重要成像技术的机会，最终促进国民健康和生活质量。技术概述光声成像提供了类似于超声的深层组织成像，但具有增强的光学对比度和额外的功能和分子成像能力。然而，与成熟的技术（超声、MRI、CT）不同，光声成像系统评估没有标准化的性能测试方法或模型。最根本的限制是缺乏材料来同时模拟组织在广泛的光学波长和声学频率范围内的特性。这使得研究人员、仪器制造商和监管机构没有明确的策略来评估设备的安全性和有效性。这项工作将创造稳定的、与生物相关的成像幽灵，具有良好的光学吸收/散射系数、声阻抗等特征，在广泛的光学波长和声学频率范围内广泛模拟组织。文献检索和实验室研究将确定合适的材料，如聚丙烯酰胺水凝胶或新型聚氯乙烯塑料溶胶配方。内在特性将在FDA使用经过验证的分光光度法和声脉冲传输方法和设备进行测量。一旦幻影材料配方得到优化，我们将构建几种特定配置的幻影，以评估图像质量指标，如空间分辨率，穿透深度等。然后，这些新的幻影将与三种具有完全不同工作参数范围（例如光学波长）的光声系统一起使用。图像质量指标将在设备之间进行比较，以阐明系统之间的性能权衡以及系统设计选择和幻影属性对性能的总体影响。目标是产生具有6个月稳定性的幽灵，在光谱上模拟血红蛋白和脱氧血红蛋白，并包含能够进行图像质量测试的目标。结果将是一个经过良好验证的组织模拟模型，以支持设备开发人员并为监管决策提供信息，包括用作潜在的FDA医疗设备开发工具。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL SUMMARYUltrasound is a powerful tool to image diseases including cancer, orthopedic disorders, and heart function. One limitation of ultrasound is that it suffers from low contrast between the region of interest versus the background tissue. Therefore, there is a wide body of research into a special kind of ultrasound known as photoacoustic imaging. Photoacoustic imaging uses light to generate sound only in the area of interest. This increases the contrast. Unfortunately, photoacoustic ultrasound is not yet approved for widespread use in people. This might be partially due to a lack of standardization devices and methods to validate the novel imaging equipment that is needed for photoacoustic imaging. Therefore, this proposed work will create specialized plastic objects with known optical and acoustic properties suitable for calibrating and standardizing photoacoustic imaging equipment. This proposal combines expertise from academia and the Food and Drug Administration to create test objects and methods that will be useful to instrument manufacturers and physicians. The resulting test objects will improve knowledge of how to best create photoacoustic imaging instrumentation and might also streamline regulatory approval of this equipment. In turn, this will increase patient access to this important imaging technique to ultimately advance the national health and quality of life. TECHNICAL SUMMARYPhotoacoustic imaging provides deep tissue imaging similar to ultrasound but with enhanced optical contrast and additional functional and molecular imaging capabilities. However, no standardized performance test methods or phantoms exist for photoacoustic imaging system evaluation unlike mature techniques (ultrasound, MRI, CT). The fundamental limitation is a lack of materials to simultaneously simulate tissue properties over a broad range of optical wavelengths and acoustic frequencies. This leaves investigators, instrument manufacturers, and regulatory agencies without clear strategies to evaluate device safety and effectiveness. This proposed work will create stable, biologically relevant imaging phantoms with well-characterized optical absorption/scattering coefficients, acoustic impedance, etc. that broadly simulate tissue over a wide range of optical wavelengths and acoustic frequencies. A literature search and laboratory study will identify suitable materials such as polyacrylamide hydrogels or novel polyvinyl chloride plastisol formulations. Intrinsic properties will be measured using well-validated spectrophotometry and acoustic pulse transmission methods and equipment at FDA. Once the phantom material formulations have been optimized, we will construct phantoms in several specific configurations to evaluate image quality metrics such as spatial resolution, penetration depth, etc. These novel phantoms will then be used with three photoacoustic systems with substantially different operating parameter ranges (e.g. optical wavelengths). Image quality metrics will be compared between devices to elucidate performance trade-offs between systems and the overall impact of system design choices and phantom properties on performance. The goal is to produce phantoms with 6-month stability that spectrally mimic hemoglobin and deoxyhemoglobin and contain targets that enable image quality testing. The outcome will be a well-validated tissue-mimicking phantom to support device developers and inform regulatory decision-making including use as potential FDA Medical Device Development Tools.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.