1. Department of Neurology and Neurosurgery; University of Tartu; Tartu; Estonia
2. Department of Neuroscience, Neurology; Uppsala University; Uppsala; Sweden
3. Department of Nuclear Medicine; North Estonian Medical Center; Tallinn; Estonia
4. Department of Radiology; North Estonian Medical Center; Tallinn; Estonia
5. Department of Chemistry; Biomedical Center; Analytical Chemistry; Uppsala University; Uppsala; Sweden