Patent ID: 8506932

Claim:
A compound of Formula I: or a salt thereof, wherein said compound is labelled with an imaging moiety, and wherein: X 1 and X 2 are independently selected from hydrogen, halogen, C 1-6 alkoxy, C 1-6 alkyl; R 1 and R 2 are independently selected from C 1-6 alkyl, C 1-6 aminoalkyl, C 1-6 alkoxyalkyl, C 1-6 alkoxy, C 1-6 hydroxyalkyl, a polyethylene glycol (PEG) group, C 3-10 cycloalkyl, C 3-10 cycloethers, and C 3-10 cycloamines; R 3 is C 1-6 [ 18 F]fluoroalkyl; R 4 is hydrogen, C 1-6 alkyl, C 1-6 alkanoyl, C 1-6 cycloalkyl, C 1-6 fluoroalkyl, hydroxy, or halogen; Y 1 is S, SO, SO 2 , or CH 2 ; and, n is 0 to 10.