Multi-Emission Radioisotope - Marine Animal Imaging Device+ (MERMAID+)

美人鱼+旨在使小型水生动物的体内放射性同位素成像成为可能。为此，我们将开发和表征一种用于小型鱼类和贻贝正电子发射断层扫描(PET)的概念验证(PoC)设备，并探索其与其他成像方式的结合。从长远来看，美人鱼+的概念将应用于可持续养鱼研究(综合多营养水产养殖)和生物医学研究，因为某些鱼种(例如斑马鱼)正越来越多地被用作各种人类疾病(阿尔茨海默氏症、糖尿病、动脉硬化……)的模型。由于专门用于啮齿动物的PET扫描仪的开发，使用特定的放射性示踪剂在临床前和翻译研究方面取得了重大进展。不幸的是，对鱼类的体内功能成像仍然非常有限。虽然对于透明的幼体来说，光学方法可能就足够了，但对于成年斑马鱼和其他鱼类物种，需要更多的模式；另一方面，鱼类的分子核成像仍然具有挑战性。美人鱼+旨在应对这些挑战。在“多发射放射性同位素--海洋动物成像设备”(美人鱼)项目(美人鱼)范围内开展了初步工作，该项目由欧盟--TRANCE一年期种子基金提供支持。在美人鱼+中，我们的两模块PET原型将升级到16个模块，并将安装一个CT设备。将使用专用模体进行校准和表征。利用内务部。在3D打印技术方面，将开发一个鱼类模型，以及一个专用的成像室。后者包括淡水和麻醉供应以及温和的鱼类固定。对于发射伽马射线的非纯PET示踪剂的可能使用，我们将通过蒙特卡罗模拟的方法来研究PET与康普顿相机(CC)的结合。CC的目的是通过检测单次伽马射线来提高检测灵敏度；还应补充断层扫描信息。为了利用这一独特的混合检测概念，我们将开发一种新的图像重建算法，能够将PET和CC数据联合重建为单一图像。这一新方法需要内部审计。这两种模式的放射性衰变和探测过程的专用和匹配模型。将模拟图像质量的模体，以研究不同的放射性同位素、构型和重建方法对图像的影响。美人鱼+这包含了极具原创性的研究：充满水的成像室的POC系统、重建算法和新颖的应用。美人鱼+的研究结果与那些专注于鱼类生理和病理的研究领域相关。此外，我们的方法对其他领域也很有意义，因为设想的软件可以转移到其他应用和成像配置上，FISH成像室可以适应其他成像方式或商业扫描仪。

MERMAID+ aims to make in-vivo radioisotope imaging of small aquatic animals practicable. To this end, we will develop and characterize a proof-of-concept (PoC) device for positron emission tomography (PET) dedicated to small fish and mussels, and explore its combination with other imaging modalities. In the long-term, the MERMAID+ concept will be applied to research on sustainable fish farming (integrated multi trophic aquaculture) and biomedical research, as certain fish species (e.g. zebrafish) are being increasingly used as models for various human diseases (Alzheimer, diabetes, arteriosclerosis...). Thanks to the development of dedicated PET scanners for rodents, significant advances in pre-clinical and translational research have been achieved using specific radiotracers. Unfortunately, in-vivo functional imaging of fish is still very limited. While for transparent larvae optical methods might be sufficient, for adult zebrafish and other fish species further modalities are desired; on the other hand, molecular nuclear imaging for fish remains challenging. MERMAID+ aims to address these challenges. Preliminary work has been carried out within the project "Multi-Emission Radioisotopes - Marine Animal Imaging Device" (MERMAID), supported by one-year EU-ATTRACT seed funds. Within MERMAID+, our two-module PET prototype will be upgraded to 16 modules, and a CT device will be incorporated. Calibration and characterisation will be carried out with dedicated phantoms. Using i.a. 3D-printing technology, a fish phantom will be developed, as well as a dedicated imaging chamber. The latter includes fresh-water and anaesthesia supply and gentle fish immobilization. Regarding the possible use of non-pure PET tracers with emission of gamma rays, we will investigate the combination of PET with a Compton camera (CC) by means of Monte-Carlo simulations. The CC aims to increase the detection sensitivity by detecting single gamma rays; t should also complementary tomographic information. To exploit this unique hybrid detection concept, we will develop a novel image reconstruction algorithm capable to jointly reconstruct PET and CC data into a single image. This new approach requires i.a. dedicated and matched models of radioactive decay and detection processes for the two modalities. Image-quality phantoms will be simulated to study the effects on the image of various radioisotopes, configurations and reconstruction approaches. MERMAID+ this contains extremely original research: PoC system with water-filled imaging chamber, reconstruction algorithms, and novel application. The outcomes of MERMAID+ are relevant for those research fields that focus on the physiology and pathology of fish. Additionally, our methods are also of interest for other areas, as the envisioned software can be transferred to other applications and imaging configurations, and the fish imaging chamber can be adapted to other imaging modalities or commercial scanners.