The present invention relates to novel compounds of formula (I) or detectably labeled compounds thereof, stereoisomers, racemic mixtures, pharmaceutically acceptable salts, hydrates or solvates, which are useful for imaging and determining the amount of alpha-
synuclein aggregates. Furthermore, the compounds may be used to diagnose a
disease, disorder or disorder associated with alpha-
synuclein aggregates (e.g., Parkinson's
disease or e.g., or multi-
system atrophy (MSA)), to determine a susceptibility to the
disease, disorder or disorder, to predict a prognosis of the disease, disorder or disorder, and to diagnose a disease, disorder or disorder associated with alpha-
synuclein aggregates. In some embodiments, disease evolution in a patient suffering from the disease, disorder or
abnormality is monitored, progression of the disease, disorder or
abnormality is monitored, and responsiveness of a patient suffering from the disease, disorder or
abnormality to its treatment is predicted.