Dynamic focussing photoacoustic microscopy of angiogenesis in vivo

体内血管生成的动态聚焦光声显微镜

• 批准号: 329389797
• 负责人: Professor Dr. Holger Gerhardt
• 金额: --
• 依托单位: Institut für Physik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/329389797?language=en
• 关键词: Dynamic; focussing; photoacoustic; microscopy; angiogenesis

Photoacoustic (PA) microscopy relies on the absorption of short optical pulses to generate ultrasound waves within the tissue. These waves propagate to the surface of the target organism where time-resolved PA signals are detected by single ultrasound transducers or transducer arrays. This allows high resolution, sub-micron 3-D images to be obtained, which show the spatial distributions of the tissue chromophores. PA microscopy combines a number of powerful attributes, such as single cell resolution and strong absorption-based contrast in vascularised soft tissues. This is used to exploit the differences in the absorption spectra of oxy- and deoxyhaemoglobin for making quantitative measurements of functional parameters, such as blood oxygen saturation, blood flow, and total haemoglobin concentration. High-speed PA microscopy has enabled the visualisation of the change in oxygen saturation in propagating single red blood cells. In addition, PA microscopy allows the detection of genetic reporters, such as fluorescent and photoswitchable proteins. While piezoelectric ultrasound detectors are the most widely used, they have distinct drawbacks, such as a resonant frequency response and opacity, which adversely affect the acoustic sensitivity of the imaging system due to, for example, large source-detector distances. Fabry-Pérot interferometer (FPI) ultrasound sensors have been shown to provide diffraction-limited element sizes, high acoustic sensitivity, near-uniform frequency response, and optical transparency for efficient backward mode PA imaging, i.e. excitation and detection on the same side of the target. Additional key advantages of using FPI sensors for PA microscopy, rather than conventional piezoelectric detectors, lie in minimal source-detector distances and acoustic impedance mismatches. This will result in major increases in acoustic sensitivity compared to current methods and an improvement in the accuracy of quantitative PA microscopy. This project aims to combine FPI ultrasound sensor technology with PA microscopy by developing novel detection geometries and sensor readout schemes to enable dynamic focussing of the acoustic detection, i.e. the combination of multi-scale OR-PAM and AR-PAM capability in one instrument. Dynamic focussing PA microscopy will be combined with other optical microscopy platforms, such as scanning confocal fluorescence, MP and super-resolution microscopy. In addition, methods for in vivo quantitative, functional PA microscopy of angiogenesis in preclinical studies will be developed. Multiwavelength PA microscopy will be used to image blood flow and oxygenation, and molecular imaging of reporter proteins, such as photoswitchable phytochromes. This will enable simultaneous functional and molecular microscopy of growing blood vessels to study the effect of blood flow and oxygenation on the role of epithelial cells during angiogenesis.

光声（PA）显微镜依靠吸收短光脉冲在组织内产生超声波。这些波传播到目标生物的表面，在那里时间分辨PA信号被单个超声换能器或换能器阵列检测到。这允许获得高分辨率的亚微米三维图像，显示组织发色团的空间分布。PA显微镜结合了许多强大的属性，如单细胞分辨率和基于血管软组织的强吸收对比度。这是用来利用在氧和脱氧血红蛋白的吸收光谱的差异，使定量测量功能参数，如血氧饱和度，血流量和总血红蛋白浓度。高速PA显微镜能够观察到单个红细胞在繁殖过程中氧饱和度的变化。此外，PA显微镜允许检测遗传报告，如荧光和光切换蛋白。虽然压电超声探测器是应用最广泛的，但它们有明显的缺点，如谐振频率响应和不透明性，这对成像系统的声灵敏度有不利影响，例如，由于源-探测器距离大。法布里-普氏干涉仪（FPI）超声传感器已被证明具有衍射限制元件尺寸、高声学灵敏度、近乎均匀的频率响应和光学透明度，可用于高效的后向模式PA成像，即在目标的同一侧激发和检测。与传统的压电探测器相比，使用FPI传感器用于PA显微镜的另一个关键优势在于最小的源-探测器距离和声阻抗不匹配。与目前的方法相比，这将大大提高声学灵敏度，并提高定量PA显微镜的准确性。该项目旨在通过开发新的检测几何形状和传感器读出方案，将FPI超声传感器技术与PA显微镜相结合，实现声学检测的动态聚焦，即在一台仪器中结合多尺度OR-PAM和AR-PAM能力。动态聚焦PA显微镜将与其他光学显微镜平台相结合，如扫描共聚焦荧光、MP和超分辨率显微镜。此外，将开发用于血管生成临床前研究的体内定量、功能性PA显微镜方法。多波长PA显微镜将用于血流和氧合成像，以及报告蛋白的分子成像，如光开关光敏色素。这将使生长血管的功能和分子显微镜能够同时研究血管生成过程中血流和氧合对上皮细胞作用的影响。