Radiolabeled compounds and uses thereof

A compound having the formula:

• or a pharmaceutically acceptable salt thereof,
• wherein:
• r and s are each independently an integer ranging from 0 to 6;
• R1 is —H, -aryl, —C1-C6 alkyl, —C3-C7 cycloalkyl, —C3-C7 cycloalkenyl, or -3- to 7-membered heterocycle;
• R2 is —H, -aryl, —C1-C6 alkyl, —C3-C7 cycloalkyl, —C3-C7 cycloalkenyl, -3- to 7-membered heterocycle, -halo, —CF3, —C2-C6 alkenyl, —C2-C6 alkynyl, —N(R4)2, —CN, —OR4 or —SR4;
• R3 is -aryl or -5- to 7-membered aromatic heterocycle, each of which is substituted with one R6 group and optionally substituted with one or more of the following groups:
• —C1-C6 alkyl, —C3-C7 cycloalkyl, —C3-C7 cycloalkenyl or -3- to 7-membered heterocycle, -halo, —CF3, —C2-C6 alkenyl, —C2-C6 alkynyl, —(C1-C6 alkylene)-aryl, —N(R4)2, —CN, —OR4, —SR4, —S(O)—R4, —SO2—R4, —SO2NH—R4, —SO3H, —NH—SO2—R4, —C(O)R5 or —NHC(O)R5;
• each occurrence of R4 is independently —H, —C1-C6 alkyl, —C2-C6 alkenyl, —C2-C6 alkynyl, -aryl, —(C1-C6 alkylene)-aryl, —C3-C7 cycloalkyl, —C3-C7 cycloalkenyl or -3- to 7-membered heterocycle;
• R5 is —R4, —N(R4)2 or —OR4;
• R6 is -M-Q, —O-M-Q, —S-M-Q, —NH-M-Q, —F, —18F, —18F-labeled CF3, —CF2H, —18F-labeled CF2H, or —11C-labeled CN;
• M is —11C-labeled C1-C6 alkylene-, —11C-labeled C2-C6 alkenylene-, —11C-labeled C2-C6 alkynylene-, —18F-labeled C1-C6 alkylene-, —18F-labeled C2-C6 alkenylene-, or —18F-labeled C2-C6 alkynylene-;
• Q is —H or -aryl.