Patent ID: 8790619

Claim:
An in vivo imaging agent of Formula I: wherein: R 1 is C 1-3 alkyl or C 1-3 fluoroalkyl; R 2 is hydrogen, hydroxyl, halo, cyano, C 1-3 alkyl, C 1-3 alkoxy, C 1-3 fluoroalkyl, or C 1-3 fluoroalkoxy; R 3 and R 4 are independently C 1-3 alkyl, C 7-10 aralkyl, or R 3 and R 4 , together with the nitrogen to which they are attached, form a nitrogen-containing C 4-6 aliphatic ring optionally comprising 1 further heteroatom selected from nitrogen, oxygen and sulfur; Y 1 is CH 2 ; and, Y 2 is CH 2 , CH 2 —CH 2 , CH(CH 3 )—CH 2 or CH 2 —CH 2 —CH 2 ; and wherein the agent of Formula I comprises an atom which is a radioisotope suitable for in vivo imaging.