In vivo imaging method

1) A method to diagnose the early stages of Parkinson's disease (PD), said method comprising:

• (i) administering to a subject a detectable quantity of an in vivo imaging agent, wherein said in vivo imaging agent comprises an α-synuclein binder labelled with an in vivo imaging moiety, and wherein said in vivo imaging agent binds to α-synuclein with a binding affinity of 0.1 nM-50 μM;
• (ii) allowing said administered in vivo imaging agent of step (i) to bind to α-synuclein deposits in the autonomic nervous system (ANS) of said subject;
• (iii) detecting signals emitted by said bound in vivo imaging agent of step (ii) using an in vivo imaging method;
• (iv) generating an image representative of the location and/or amount of said signals;
• and,
• (v) using the image generated in step (iv) to determine of the presence of, or susceptibility to, PD.