FDA Scholar Program: Blood-Mimicking Phantoms for Assessing Oximetry Performance of Photoacoustic Imaging Systems

FDA 学者计划：用于评估光声成像系统血氧饱和度性能的模拟血液模型

• 批准号: 2149602
• 负责人: Jesse Jokerst
• 金额: $ 10万
• 依托单位: University of California-San Diego
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-02-01 至 2024-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2149602&HistoricalAwards=false
• 关键词: FDA; Scholar; Program; Blood; Mimicking; FDA; Scholar; Program; Blood; Mimicking

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 (contrast is the difference in signal intensity between the region of interest and the background tissue). Therefore, there is a large 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 devices and methods to validate and standardize the novel imaging equipment needed for photoacoustic imaging. Therefore, this work will create specialized plastic objects with optical and acoustic properties that mimic human tissue with different amounts of tissue oxygenation. These objects can be used to calibrate and standardize photoacoustic imaging equipment. This proposal combines expertise from academia and the Food and Drug Administration to identify materials that have similar optical and acoustic properties as human tissue. We will then add dyes that have absorption spectra similar to hemoglobin. The resulting test objects will improve knowledge of how to best create photoacoustic imaging instrumentation that measures tissue oxygenation 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 health and quality of life of US taxpayers. 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 such as computed tomography. The fundamental limitation—and scientific problem to be studied here—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. Our prior work with the Food and Drug Administration (FDA) built 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. We will now integrate chromophores to simulate tissue oxygenation (SO2) over a range of oxygen saturation/perfusion values. Objective 1 of this research will develop phantoms that simulate blood oxygen-dependent photoacoustic spectra. Combinations of dyes will be selected to develop tunable formulations that reproduce blood-like multispectral photoacoustic signals at sets of discrete optical wavelengths commonly used for photoacoustic oximetry. Photoacoustic-derived SO2 measurements will be compared against ground truth values as well as against photoacoustic measurements in bovine blood with variable SO2. Ground truth SO2 of bovine blood will be measured by oximetry. Objective 2 will use the phantoms to establish quantitative oximetry test methods. These methods will be performed on three different photoacoustic systems located at UCSD and FDA. Phantoms with different background optical properties and containing blood-mimicking inclusions at different depths and mimicked SO2 levels will be used for parametric study of photoacoustic device oximetry performance. Improvements in the SO2 measurement accuracy of our three photoacoustic systems using various fluence correction algorithms will be quantified to determine device sensitivity to tissue properties and morphology.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.

非技术总结超声是图像疾病，包括癌症，骨科疾病和心脏功能的强大工具。超声波的一种局限性是，它的对比度低（对比是感兴趣区域和背景组织之间信号强度的差异）。因此，对一种特殊的超声（称为光声成像）进行了大量研究。光声成像使用光才能在感兴趣的领域产生声音，这增加了对比度。不幸的是，光声超声尚未批准用于人们的宽度使用。这可能部分是由于缺乏验证和标准化光声成像所需的新型成像设备的设备和方法。因此，这项工作将创建具有光学和声学特性的专门塑料物体，这些物体模仿人体组织具有不同量的组织氧合。这些对象可用于校准和标准化光声成像设备。该建议结合了学术界的专业知识和食品和药物管理局，以识别具有与人体组织相似的光学和声学特性的材料。然后，我们将添加具有类似于血红蛋白的抽象光谱的染料。最终的测试对象将提高如何最好地创建光声成像仪器，以测量组织氧合，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种重要成像技术的机会，以最终提高美国纳税人的健康和生活质量。技术总结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以及其他功能和分子成像功能。但是，与成熟技术（例如计算机断层扫描）不同，没有用于光声成像系统评估的标准化性能测试方法或幻影。基本限制以及这里要研究的科学问题 - 缺乏在广泛的光波长和声学频率上同时模拟组织特性的材料。这使研究人员，仪器制造商和监管机构没有明确的策略来评估设备安全性和有效性。我们先前与食品药品监督管理局（FDA）建立了稳定的，具有生物学相关的成像幻象，具有良好的光吸收/散射系数，声学阻抗等，它们在各种光学波长和声学频率上广泛模拟组织。现在，我们将整合发色团以模拟一系列氧饱和/灌注值的组织氧合（SO2）。这项研究的目标1将开发模拟血氧依赖的光声光谱的幻象。将选择染料的组合来开发可调式公式，以在通常用于光声氧仪的一组离散光波长下重现鲜血的多光谱光声信号。将比较光声衍生的SO2测量值与地面真相值以及与具有可变SO2的牛血的光声测量值进行比较。牛血的地面真理SO2将通过血氧仪测量。目标2将使用幻影来建立定量的血氧仪测试方法。这些方法将在UCSD和FDA的三个不同的光声系统上执行。具有不同背景光学特性并在不同深度和模仿SO2水平的含有血液的夹杂物的幻影将用于光声器械血氧仪性能的参数研究。使用各种通力校正算法的三个光声系统的SO2测量精度的改善将被量化以确定对组织性能和形态学的设备敏感性。该奖项反映了NSF的法定任务，并被认为是通过基金会的知识分子和广泛影响的评估来通过评估来支持的珍贵。