Optical absorption contrast, large imaging depth at ultrasonic resolution, and the potential of functional/quantitative imaging are the features driving the rapid development of photoacoustic (PA) imaging. For quantitative and functional PA imaging, the fluence distribution is required to transform a PA image to a map of absorption coefficients. A suitable method to estimate the fluence for in vivo applications must not require a priori knowledge of the medium optical properties, should work for various illumination conditions, and must be applicable to different PA imaging geometries. Existing methods of estimating fluence in tissue do not meet these requirements simultaneously. Here we present a method to measure the fluence distribution in tissue using acousto-optics (AO) that meets all the above requirements. We developed a PA and AO tomography system for small-animal imaging to investigate the potential and the feasibility of fluence-corrected PA imaging using our method in a single instrument. We performed experiments on phantoms, an ex vivo tissue sample, and freshly sacrificed mice. We demonstrate that the correction for spatial and spectral fluence variations in PA images establishes the direct relation between image value and optical absorption, which in turns improves the quantitative estimation of blood oxygen saturation.

中文翻译：

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光声和声光层析成像技术，用于定量和功能成像

光吸收对比度，超声分辨率下的大成像深度以及功能/定量成像的潜力是推动光声（PA）成像快速发展的特征。对于定量和功能性PA成像，需要注量分布以将PA图像转换为吸收系数图。估算体内应用注量的合适方法不必先验具有中等光学特性的知识，应该适用于各种照明条件，并且必须适用于不同的PA成像几何形状。现有的估计组织通量的方法不能同时满足这些要求。在这里，我们提出了一种使用声光（AO）来测量组织中注量分布的方法，该方法可以满足所有上述要求。我们开发了用于小动物成像的PA和AO层析成像系统，以在单个仪器中使用我们的方法研究通过注量校正的PA成像的潜力和可行性。我们的幻影，一个进行实验，体外组织样本和新鲜处死的小鼠。我们证明，PA图像中空间和光谱注量变化的校正建立了图像值和光吸收之间的直接关系，从而改善了血氧饱和度的定量估计。