Ultrasound mediated bioluminescence tomography for high sensitivity, high spatial resolution 3D imaging

光学成像是一种独特而强大的技术，可以在人体实验技术的原理中实现“细化”和“简化”。使用传统的疾病模型，在确定的时间点处死受感染的动物(3-10只)，并切除组织以确定病原体数量和定位。例如，一个六个时间点的实验将导致使用18-60只动物。相比之下，光学成像的非侵入性使得只需对同一组动物中检测到的可见光或近红外信号成像，通常总共六到八个，就可以监测感染的过程。重要的是，在整个实验中对同一动物进行多次成像，可以极其准确和一致地跟踪疾病的进展，同时允许每种动物充当自己的对照。使用光学成像有一个主要缺点，因为光被组织严重散射，导致图像质量较差。例如，在追踪组织中的干细胞时，光学散射意味着我们不能准确地知道细胞在体内的哪里，有多少细胞处于特定的位置，以及它们的作用是什么。这严重阻碍了理解干细胞在帮助人体免疫反应中的使用的研究。我们建议开发一种结合超声和光学技术的成像系统，以显著提高生物发光成像的空间分辨率和灵敏度。超声波的信息将以两种方式使用来解决这个问题。首先，由于超声波对组织的机械性能做了很小的改变，这可以用来调制组织内产生的生物发光光。这提供了一种可用于精确探测组织的不同区域的调制光‘信标’，从而克服了光散射的影响，并提高了空间分辨率。其次，我们将使用超声图像来提供组织结构的3D地图。调制光信标和结构信息将被用于形成基于我们广泛使用的NIRFAST软件(www.nirfast.org)的图像重建算法。在项目过程中，该系统将在裸鼠研究中进行演示。根据我们的概念验证数据，我们预计空间分辨率将达到最大0.5 mm，而目前的技术水平为2.5 mm。这将对3R产生重大影响。替代：更好的成像将提供更准确的计算模型；减少：成像使相同的动物能够随着时间的推移使用，更准确的定量成像允许在单个研究中使用更少的动物；改进：通过提高研究结果的质量。

Optical imaging is a unique and powerful technique for implementation of 'refinement' and 'reduction' within the Principles of Humane Experimental Techniques. Using traditional disease models, infected animals (ranging between 3-10) are sacrificed at defined time points and tissues are excised for determination of pathogen numbers and localization. For example, a six time point experiment would result in the use of 18-60 animals. In contrast, the non-invasive nature of optical imaging allows the course of an infection to be monitored simply by imaging the visible or near infrared signal detected from within the same group of animals, typically six to eight in total. Importantly, multiple imaging of the same animal throughout an experiment allows disease progression to be followed with extreme accuracy and consistency, while allowing each animal to act as its own control. There is a major drawback in using optical imaging as light is heavily scattered by tissue which results in poor quality images. For example in tracking stem cells in tissue, optical scattering means that we cannot tell where precisely where the cells go in the body, how many are at a particular and what their action is. This severely hampers research into understanding the use of stem cells in aiding the body's immune response. We propose to develop an imaging system that combines ultrasound and optical techniques to significantly improve the spatial resolution and sensitivity of bioluminescence imaging. Information from the ultrasound will be used in two ways to address this problem. Firstly, as ultrasound makes a small change to the mechanical properties of the tissue, this can be used to modulate the bioluminescent light produced within the tissue. This provides a modulated light 'beacon' which can be used to precisely probe different regions of the tissue, thus overcoming the effects of light scattering and improving spatial resolution. Secondly we will use the ultrasound image to provide 3D maps of tissue structure. Both modulated light beacons and structural information will be used to inform an image reconstruction algorithm based on our widely used NIRFAST software (www.nirfast.org). The system will be demonstrated in studies of nude mice during the course of the project. Based on our proof of concept data, we anticipate that the spatial resolution will be a maximum of 0.5mm, compared to the current state of the art of 2.5mm. This will contribute to a significant impact on the 3Rs. Replacement: better imaging will inform more accurate computational models; Reduction: imaging enables the same animals to used over time and more accurate quantitative imaging allows fewer animals to be used in a single study; Refinement: through the improved quality of research findings.