Preclinical Applications of Brain PET/MRI

The two imaging techniques positron emission tomography (PET) and magnetic resonance imaging (MRI) enable advanced in vivo imaging in different fields of biomedical research. The combination of these two imaging modalities into a single device merges functional and morphologic information. High-resolution MRI of morphology with good soft-tissue contrast and spectroscopic detection of endogenous metabolite distributions is completed by means of high-sensitive PET by functional parameters such as glucose metabolism, amino acid transport, proliferation, receptor density, or drug concentration.
In preclinical research, the acquisition of PET and MR images of the same animal has been realized using different strategies in recent years. While initially most studies have been performed on separate devices with subsequent co-registration of the images, new and more integrated systems are available. Accordingly, fused images are obtained by the use of (i) separate instruments, (ii) in-line/sequential PET/MRI, or (iii) fully integrated PET/MRI scanners. Preclinical PET/MRI benefits in particular brain imaging in various small-animal models of diseases, including genetically-engineered animals. By providing a powerful tool for identification as well as functional characterization of new drug targets or disease biomarkers, the obtained information supports e.g. the development and follow-up of the efficacy of accordingly targeting drugs significantly.
Our research group at the Helmholtz-Zentrum Dresden-Rossendorf has been focused on the development of radiopharmaceuticals for brain PET imaging for almost two decades. Four newly developed radioligands for imaging of depression and dementia have been translated into human application within the last eight years. Related to the programme-oriented research within the Helmholtz Association the main emphasis of the group has recently moved into cancer research trying to visualize and characterize molecular switches which are involved in brain tumor development and progression by means of preclinical PET/MRI.