MERMAID (Multi-Emission Radioisotopes – Marine Animal Imaging Device) proposes a unique imaging approach that opens the door to unexplored research paths in various disciplines. MERMAID will be the first dedicated imaging device for radioisotope imaging of small aquatic animals, thus paving the way to innovations in sustainable aquaculture and expanding the use of zebrafish as a model for human diseases.

Its adaptive geometry will allow several fish and marine species to be studied from a new perspective. 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 recognised 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 visualised, we could count on an exceptional tool to optimise 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 flexible detector geometry, imaging of various animal shapes and sizes will be possible. One of the goals of this project is to build and characterise such a demonstrator for nuclear imaging of aquatic animals, based on state-of-the art detector components. Via computer simulations, we will combine PET with a Compton camera (CC). The latter will allow the detection sensitivity to be significantly improved, adding a high level of geometrical flexibility and complementary tomographic information. The CC should also improve MERMAID performance for non-pure positron emitters. Therefore, a large variety of radionuclides could be used.

This unique hybrid detection concept will require also a novel image reconstruction software, aimed to jointly reconstruct tomographic images from PET and CC within a single algorithm. For the delivery of the radiotracer, novel methodologies will be investigated. Aquatic micro-organisms, such as microalgae, will be used as radioactivity carriers to provide information about processes of interest, such as as feed paths and intake. This unparalleled combination of nuclear tomographic imaging with tracer transport through selected micro-organisms will break new ground for life and biomedical scientists, and sustainable aquaculture industry.