the radiochemistry is performed which is fitted to the apparatus in order to perform a radiosynthesis the cassette normally includes fluid pathways a reaction vessel and ports for receiving reagent vials as well as any solid phase extraction cartridges used in post radiosynthetic clean up steps optionally in a further embodiment of the invention the automated radiosynthesis apparatus can be linked to a high performance liquid chromatograph hplc the present invention therefore provides a cassette for the automated synthesis of a compound of the invention the radiolabeled compound of the invention as described herein may bind to nfts or tau aggregates and aid in identifying the amount of nfts tau aggregates present which in turn may correlate with the stage of ad the present invention thus provides a method of imaging comprising the step of administering a radiolabeled compound of the invention as described herein to a subject and detecting said radiolabeled compound of the invention in said subject the present invention further provides a method of detecting tau aggregates in vitro or in vivo using a radiolabeled compound of the invention as described herein hence the present invention provides better tools for early detection and diagnosis of alzheimers disease the present invention also provides better tools for monitoring the progression of alzheimers disease and the effect of treatment as would be understood by one of skill in the art the.