Patent ID: 8420052

Claim:
A compound of the formula (Ia) or a pharmaceutically acceptable salt thereof; wherein: A l is N; A 3 is CH; R 1 is halogen, OR 8 , and OR 9 ; R 8 is selected from the group consisting of H, alkyl, haloalkyl, alkenyl, haloalkenyl, alkynyl, haloalkynyl, cycloalkyl, halocycloalkyl, alkoxyalkyl, haloalkoxyalkyl, cycloalkoxyalkyl, thioalkoxyalkyl, halothioalkoxyalkyl, cyclothioalkoxyalkyl, aryl, arylalkyl, substituted aryl, substituted arylalkyl, heteroaryl, heteroarylalkyl, substituted heteroaryl, and substituted heteroarylalkyl; R 9 is selected from the group consisting of aryl, substituted aryl, heteroaryl, and substituted heteroaryl; W is N; and X is selected from the group consisting of aryl, substituted aryl, heteroaryl, and substituted heteroaryl; provided that at least one of X and R 1 comprises a halogen or a radiolabel; wherein the radiolabel is a radionuclide selected from the group consisting of 11 C, 13 N, 15 O, 18 F, 123 I, 124 I, 125 I, 131 I and 77 Br.