MERMAID (Multi-Emission Radioisotopes - Marine Animal Imaging Device) proposes a unique imaging approach that opens the door to unexplored research paths in various disciplines. Its adaptive geometry will allow several fish and marine species to be studied from a new perspective. MERMAID will be the first dedicated imaging device for radioisotope imaging of small aquatic animals, thus paving the way to expand the use of zebrafish as a model for human diseases innovations and additionally in sustainable aquaculture. In addition to gaining new basic knowledge of aquatic animals and imaging technology, several fields worldwide can benefit in the long run, e.g. to reduce the number of sacrificed mammals used as laboratory animals by increasing the utility of zebrafish or to improve sustainable fish farming. Fish are essential in several research fields, as the main target of study (e.g., aquaculture, biology) or as a "surrogate" of human physiology to develop models of disease. For the latter, zebrafish is a recognized biological model. Compared to laboratory mice, zebrafish requires less space and breed very fast. As the continuously increasing demand of fishery products negatively affects the environment, many efforts are put on developing sustainable fish farming. If food chains and their interlinking could be visualized, we could count on an exceptional tool to optimize growth rates and reduce environmental impact. Molecular imaging techniques are well-established tools to explore functional processes in living beings. In particular, Positron Emission Tomography (PET) is a widely used nuclear imaging modality in medical diagnostics and biomedical research. For the latter, rodents are often the animals of choice, and dedicated PET systems are commercially available. These scanners, however, are inappropriate for aquatic animals; available spatial resolution is insufficient for small fishes.

Through a dedicated detector geometry and flexible imaging chambers, imaging of various animal shapes and sizes will be possible. Within this project a demonstrator for nuclear imaging of aquatic animals, based on state-of-the art detector components has been developed and characterised. This demonstrator now will be extended, including a module enabling Computed Tomography (CT) to obtain additional anatomical information. For the delivery of the radiotracer, novel methodologies will be investigated. Aquatic micro-organisms, such as micro-algae, will be used as radioactivity carriers. Certain micro-organisms, when labeled with specific radionuclides and combined with an adequate imaging device, could provide relevant information about dynamic processes of interest, such as feed paths and intake.

• Fraunhofer-Einrichtung für Individualisierte und Zellbasierte Medizintechnik
• Isotopenlabor der Sektion Naturwissenschaften der Universität zu Lübeck