1. A radiolabeled compound of the Formula I to Formula VI:

Formula IV Formula V Formula VI wherein:

For Formula I:

A is N or CR ¹ ; B is N or CR ² ; J is N or CR ³ ; K is N or CR ⁴ ; L is N or CR ⁵ ; M is N or CR ⁶ ; P is N or CR ⁷ ; and Q is N or CR ⁸ , provided that no more than two of A, B, J, K, L, M, P and Q can be N;

X is a bond or is selected from the group consisting of C _1-6 alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ¹⁰ )C(S)-, -S(O)N(R ¹⁰ )- and - N(R ¹⁰ )S(O) ₂ -;

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-C _r6 alkyl, perhaloC,- ₆ alkyl, C, _-6 alkyl, C _3-6 CyC loalkyl, C _3- i ₂ cycloalkylCi. ₅ alkyl, C ₆ -i ₄ aryl, C _6- ioarylCi _-4 alkyl, heteroaryl, Ci. ₅ alkoxy, H(OCH ₂ CH ₂ )^ ₆ O-, Ci _-3 alkyl(OCH ₂ CH ₂ ) _1-6 O-, halo-Ci _-5 alkoxy, halo-Ci _-3 alkyl(OCH ₂ CH ₂ ),. ₆ O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C _3- i ₂ cycloalkylCi. ₅ alkoxy, heteroarylC _2-5 alkoxy, C _6-14 aryloxy, C _6-1 oarylCi _-4 alkoxy, heteroaryloxy, C,. ₅ alkylNR ¹⁰ C(O)-, (C,- ₆ alkyl) ₂ NC(O)CH(Ci. ₅ alkyl)-, halo- Ci- ₆ alkylNR ¹⁰ C(O)CH(C _1-5 alkyl)-, halo-C,- ₆ alkylOC(O)CH(Ci _-5 alkyl)-, halo- C, _-5 alkylNR ¹⁰ C(O)-, C _1-5 alkylNR ^I0 C(O)O-, C,. ₅ alkylC(O)-, Ci _-5 alkylC(O)O-, C _6- i ₀ arylC(O)- and C _6- i ₀ arylC(O)O-; or at least one of R ¹ and R ² , R ² and R ³ , R ³ and R ⁴ , R ⁵ and R ⁶ , R ⁶ and R ⁷ , or R ⁷ and R ⁸ together with the carbon atoms to which they

are attached to, form a substituted or unsubstituted aromatic or non-aromatic carbocyclic or heterocyclic ring; provided that at least any two of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are hydrogens;

R ⁹ is hydrogen or is selected from the group consisting of halo, Ci _-6 alkyl, C ₃ . ₆ cycloalkyl, C _3- i ₂ cycloalkylCi. ₅ alkyl, C _6- i ₄ aryl, C _6- ioarylCi_ ₄ alkyl, heteroaryl, halo-(CH ₂ CH ₂ ) _1-6 -; halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ),_ ₆ -, halo-CH ₂ CH ₂ - (OCH ₂ CH ₂ )^O(CO)- and halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ), _-6 (CO)-; each R ¹⁰ is independently H or C]- ₆ alkyl; provided that the compound of Formula I is not a compound selected from the group consisting of 2-fluoroethyl 6-fluoro-4-methoxy-9H-pyrido[3,4-b]indole-3- carboxylate, 2-fluoropropyl 6-fluoro-4-methoxy-9H-pyrido[3,4-b]indole-3- carboxylate, 9H-pyrido[3,4-b]indole-3-carboxylate, 9H-pyrido[3,4-b]indole-3- thiocarboxylate, 9H-pyrido[3,4-b]indole-3-carboxamide, 9H-pyrido[3,4-b]indole-3- carbimidate, β-carboline-3-carboxylate, β-carboline-3-thiocarboxylate, β-carboline- 3-carboxamide, β-carboline-3-carbimidate; (S)-4-(3-(3-(2'-l 8F]-fluoroethylamino)- 2-hydroxypropoxy)-carbazol, R, S, SS and SR-l '-[18F]-fluorocarazolol (FCAR) and [1 lC]-carazolol (CAR), (S)-(-)-4-(2-hydroxy-3-(l'-[18]fluoroisopropyl)- aminopropoxy)carbazole, 7-(2-fluoroethoxy)-l-methyl-9H- β-carboline, 7-(2- fluoropropoxy)-l -methyl-9H- β-carboline, 7-[2-(2-fluoroethoxy)ethoxy]-l -methyl- 9H- β-carboline, 7-{2-[2-(2-fluoroethoxy)ethoxy]ethoxy}-l-methyl-9H- β-carboline and carbazolyl-(4)-oxypropanolamine and their derivatives; wherein the radiolabel comprises a radionuclide selected from the group consisting of ^{1 1} C, ¹³ N, ¹⁵ O, ¹⁸ F, ¹²³ 1, ¹²⁴ 1, ¹²⁵ I, ¹³¹ I and ⁷⁷ Br; and pharmaceutically acceptable salts thereof; For Formula II:

X is a bond or is selected from the group consisting of Ci _-6 alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ¹⁰ )C(S)-, -S(O)N(R ¹⁰ )- and - N(R ¹⁰ )S(O) ₂ -;

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-C,- ₆ alkyl, perhaloC,- ₆ alkyl, C, _-6 alkyl, C _3-6 CVClOaIkVl, C _3- i ₂ cycloalkylCi _-5 alkyl, C _6- i ₄ aryl, heteroaryl, C,. ₅ alkoxy, H(OCH ₂ CH ₂ ) _1-6 0-, C, _-3 alkyl(OCH ₂ CH ₂ ) _1-6 O-, halo-C _1-5 alkoxy,

halo-Ci. ₃ alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C^^cycloalkylCi-salkoxy, heteroarylC ₂ - ₅ alkoxy, C ₆ -ι ₄ aryloxy, C ₆ -ioarylC] _-4 alkoxy, heteroaryloxy, C, _-5 alkylNR ¹⁰ C(O)-, (Ci- ₆ alkyl) ₂ NC(O)CH(Ci _-5 alkyl)-, halo- C , - ₆ alkylNR ' ⁰ C(O)CH(C , _-5 alkyl)-, halo-Ci - ₆ alkyl OC(O)CH(C , - ₅ alkyl)-, halo- C,. ₅ a ^] kylNR ^l0 C(O)-, C, _-5 alkylNR ¹⁰ C(O)O-, Ci_ ₅ alkylC(O)-, Ci. ₅ alkylC(O)O-, C _6- i ₀ arylC(O)- and C ₆ . , _o ary IC(O)O-; or at least one of R ¹ and R ² , R ² and R ³ , R ³ and R ⁴ , R ⁵ and R ⁶ , R ⁶ and R ⁷ , or R ⁷ and R ⁸ together with the carbon atoms to which they are attached to, form a substituted or unsubstituted aromatic or non-aromatic carbocyclic or heterocyclic ring; provided that at least any two of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are hydrogens;

R ⁹ is hydrogen or is selected from the group consisting of halo, C _3-6 cycloalkyl, heteroaryl, halo-(CH ₂ CH ₂ ), _-6 -; halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _1-6 -, halo-CH ₂ CH ₂ - (OCH ₂ CH ₂ ) _1-6 O(CO)- and halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ )i. ₆ (CO)-; each R ¹⁰ is independently H or Ci- ₆ alkyl; wherein the radiolabel comprises a radionuclide selected from the group consisting of ¹¹ C, ¹³ N, ¹⁵ O, ¹⁸ F, ¹²³ 1, ¹²⁴ 1, ¹²⁵ I, ¹³¹ I and ⁷⁷ Br; and pharmaceutically acceptable salts thereof; For Formula III:

Y and Y' are each independently a bond or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , - C(S)NH ₂ , haloCi- ₆ alkyl, perhalod- ₆ alkyl, C _1-6 alkyl, C ₃ . ₆ cycloalkyl, C ₃ -i ₂ cycloalkylCi _-5 alkyl, C ₆ _i ₄ aryl, C ₆ -ιoarylC _)-4 alkyl, heteroaryl, Ci-salkoxy, H(OCH ₂ CH ₂ ) _L6 O-, C _I-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-C,. ₅ alkoxy, halo-Ci. ₃ alkyl(OCH ₂ CH ₂ ), _-6 O-, halo-CH ₂ CH ₂ O-, C ₃ . ₆ cycloalkoxy, C ₃ .i ₂ cycloalkylCi- ₅ alkoxy, heteroarylC ₂ . ₅ aIkoxy, C ₆ -i ₄ aryloxy, and heteroaryloxy when R ¹ ' and R ¹² are absent;

R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-C _r6 alkyl, perhaloCi- ₆ alkyl, C, _-6 alkyl, C _3-6 cycloalkyl, H(OCH ₂ CH ₂ ) _1-6 O-, C,. ₃ alkyl(OCH ₂ CH ₂ ) _1-6 O-, halo-C _1-5 alkoxy, halo-Ci _-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, ImIo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy,

heteroarylC _2-5 alkoxy, C _6- ] ₄ aryloxy, C _6- ioarylCi _-4 alkoxy, heteroaryloxy, C,. ₅ alkylNR ¹⁰ C(O)-, (C,- ₆ alkyl) ₂ NC(O)CH(Ci. ₅ alkyl)-, halo- C , - ₆ alkylNR ' ⁰ C(O)CH(C , _-5 alkyl)-, halo-C , - ₆ alkylOC(O)CH(C , _-5 alkyl)-, halo- C,. ₅ alkylNR ¹⁰ C(O)-, C _l-5 alkylNR ¹⁰ C(O)O-, Ci _-5 alkylC(O)-, C _1-5 alkylC(O)O-, C _6- i ₀ arylC(O)- and C _6- ] ₀ arylC(O)O-; or at least one of R ⁵ and R ⁶ , R ⁶ and R ⁷ or R ⁷ and R together with the carbon atoms to which they are attached to, form a substituted or unsubstituted aromatic or non-aromatic carbocyclic or heterocyclic ring; provided that at least one of R ⁵ , R ⁶ , R ⁷ and R ⁸ is a hydrogen; each R ¹⁰ is independently H or Ci- ₆ alkyl;

R ¹¹ and R ¹² are each independently absent, a hydrogen or are each independently selected from the group consisting of halo, Ci _-6 alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi. ₅ alkyl, C ₆ -i ₄ aryl, Ce-ioarylC^alkyl, heteroaryl, halo-(CH ₂ CH ₂ )i^-, halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ),. ₆ -, halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ), _-6 O(CO)- and halo- CH ₂ CH ₂ -(OCH ₂ CH ₂ ) , ₆ (CO)- ; wherein the radiolabel comprises a radionuclide selected from the group consisting of ¹¹ C, ¹³ N, ¹⁵ O, ¹⁸ F, ¹²³ 1, ¹²⁴ I, ¹²⁵ I, ¹³¹ I and ⁷⁷ Br; and pharmaceutically acceptable salts thereof; For Formula IV:

W is O or -N-X-R ⁹ ;

X is a bond or is selected from the group consisting of Ci _-6 alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ^I0 )C(S)-, -S(O)N(R ¹⁰ )- and - N(R'°)S(O) ₂ -;

Y and Y' are each independently a bond or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , - C(S)NH ₂ , halo-C i- ₆ alkyl, perhaloCi- ₆ alkyl, C _1-6 alkyl, C _3-6 cycloalkyl, C ₃ _i ₂ cycloalkylCi _-5 alkyl, C ₆ -i ₄ aryl, heteroaryl, Ci _-5 alkoxy, H(OCH ₂ CH ₂ ), _-6 O-, C _1-3 alkyl(OCH ₂ CH ₂ ) _1-6 O-, halo-Ci _-5 alkoxy, halo-C, _-3 alkyl(0CH ₂ CH ₂ )i _-6 0-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C _3- i ₂ cycloalkylCi. ₅ alkoxy, heteroarylC _2-5 alkoxy, C _6- i ₄ aryloxy, C ₆ -ioarylCi _-4 alkoxy and heteroaryloxy when R ^{1 1} and R ¹² are absent; or Y is

and R ¹² is absent;

R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹ , -C(O)NH ₂ , -C(S)NH ₂ , halo-Crβalkyl, perhaloC,- ₆ alkyl, C,. ₆ alkyl, C ₃ - ₆ cycloalkyl, C ₃ -i ₂ cycloa]kylCi. ₅ alkyl, C ₆ -i ₄ aryl, C _ό -ioarylCi^alkyl, heteroaryl, Ci.salkoxy, H(OCH ₂ CH ₂ )^O-, C,. ₃ alkyl(OCH ₂ CH ₂ )i- ₆ θ-, halo-C _I-5 alkoxy, halo-Ci _-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-CH ₂ CH ₂ O-, C ₃ . ₆ cycloalkoxy, C ₃ -i ₂ cycloalkylCi- ₅ alkoxy, heteroarylC _2-5 alkoxy, C _6- i ₄ aryloxy, C ₆ -ioarylCi_ ₄ aIkoxy, heteroaryloxy, C, _-5 alkylNR ¹⁰ C(O)-, (C,- ₆ alkyl) ₂ NC(O)CH(C, _-5 alkyl)-, halo- C i - ₆ alkylNR ¹⁰ C(O)CH(C , _-5 alkyl)-, halo-C , - ₆ alkylOC(O)CH(C , _-5 alkyl)-, halo- Ci _-5 alkylNR ¹⁰ C(O)-, Ci _-5 alkylNR ¹⁰ C(O)O-, Ci _-5 alkylC(O)-, Ci_ ₅ alkylC(O)O-, C ₆ -i ₀ arylC(O)- and C _6-10 arylC(O)O-; or at least one of R ⁵ and R ⁶ , R ⁶ and R ⁷ or R ⁷ and R ⁸ together with the carbon atoms to which they are attached to, form a substituted or unsubstituted aromatic or non-aromatic carbocyclic or heterocyclic ring; provided that at least one of R ¹ , R ² , R ³ and R ⁴ is a hydrogen;

R ⁵ , R ⁶ , R ⁷ , R ⁸ and R° are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-Ci- ₆ alkyl, perhaloC,- ₆ alkyl, C,. ₆ alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi _-5 alkyl, C _ό -uaryl, C ₆ -ioarylCi _-4 alkyl, heteroaryl, C,. ₅ alkoxy, H(OCH ₂ CH ₂ ) ,. ₆ O-, C _1-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-C,. ₅ alkoxy, halo-C, _-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C ₃ -i ₂ cycloalkylCi- ₅ alkoxy, heteroarylC _2-5 alkoxy, C _6- i ₄ aryloxy, heteroaryloxy, C, _-5 alky INR ¹⁰ C(O)-, (Q-ealkyl^NC^CHtCsalkyl)-, halo- Ci- ₆ alkylNR ¹⁰ C(O)CH(C, _-5 alkyl)-, halo-C _r6 alkylOC(O)CH(Ci _-5 alkyl)-, halo- C,. ₅ alkylNR ¹⁰ C(O)-, Ci _-5 alkylNR ¹⁰ C(O)O-, C _1-5 alkylC(O)-, C,. ₅ alkylC(O)O-, C _6- i ₀ arylC(O)- and C ₆ -ι ₀ arylC(O)O-;

R ⁹ is hydrogen or is selected from the group consisting of halo, Ci _-6 alkyl, C _3-6 cycloalkyl, Cs.^cycloalkylCi^alkyl, C ₆ .i ₄ aryl, C ₆ -ioarylCi _-4 alkyl, heteroaryl, halo-(CH ₂ CH ₂ ) _l-6 -; halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _{1 -6} -, halo-CH ₂ CH ₂ - (OCH ₂ CH ₂ ) _L6 O(CO)- and halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ), _-6 (CO)-;

each R ¹⁰ is independently H or C _h alky];

R ¹¹ and R ¹² are each independently absent, a hydrogen or are each independently selected from the group consisting of halo, Ci _-6 alkyl, C ₃ - ₆ cycloalkyl, C _3- i ₂ cycloalkylCi _-5 alkyl, C _6-)4 aryl, C ₆ -ioarylCi _-4 alkyl, heteroaryl, halo-(CH ₂ CH ₂ )i- ₆ -; halo-CH ₂ CH ₂ -(OCH ₂ CH2), _-6 -, halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ),. ₆ O(CO)- and halo- CH ₂ CH ₂ -(OCH ₂ CH ₂ ) , ^(CO)-; wherein the radiolabel comprises a radionuclide selected from the group consisting of ^{1 1} C, ¹³ N, ¹⁵ O, ¹⁸ F, ¹²³ 1, ¹²⁴ 1, ¹²⁵ I, ¹³¹ I and ⁷⁷ Br; and pharmaceutically acceptable salts thereof; For Formula V:

X is a bond or is selected from the group consisting of -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ^l0 )C(O)-, -N(R ¹⁰ )C(S)-, -S(O)N(R ¹⁰ )- and - N(R ¹⁰ )S(O) ₂ -;

R ⁵ and R ⁶ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-C ₂ - ₆ alkyl, perhaloC,- ₆ alkyl, Ci _-6 alkyl, C _3-6 cycloalkyl, C ₃ -i ₂ cycloalkylC|. ₅ alkyl, C _6- i ₄ aryl, heteroaryl, Ci.salkoxy, H(OCH ₂ CH ₂ ) _I-6 O-, Ci _-3 alkyl(OCH ₂ CH ₂ ) _1-6 O-, halo-C _1-5 alkoxy, halo-Ci _-3 alkyl(OCH ₂ CH ₂ ),. ₆ O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C ₃ _i ₂ cycloalkylCi_ ₅ alkoxy, heteroarylC _2-5 alkoxy, C ₆ -i ₄ aryloxy, heteroaryloxy, C,. ₅ alkylNR ¹⁰ C(O)-, (Ci- ₆ alkyl) ₂ NC(O)CH(C _1-5 alkyl)-, halo- C i - ₆ alkylNR ¹⁰ C(O)CH(C i . ₅ alkyl)-, halo-C, - ₆ alkylOC(O)CH(C , _ ₅ alkyl)-, halo- C,. ₅ alkylNR ¹⁰ C(O)-, Ci_ ₅ alkylNR ¹⁰ C(O)O-, Ci _-5 alkylC(O)-, C _! _ ₅ alkylC(O)O-, C ₆ -ioarylC(0)- and C ₆ -ioarylC(0)0-; or R ⁵ and R ⁶ together with the carbon atoms to which they are attached to, form a substituted or unsubstituted aromatic or non- aromatic carbocyclic or heterocyclic ring;

R ⁹ is hydrogen or is selected from the group consisting of halo, Ci _-6 alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi _-5 alkyl, C _6- i ₄ aryl, C ₆ -ioarylCi _-4 alkyl, heteroaryl, halo-(CH ₂ CH ₂ ), _-6 -; 1IaIo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _L6 -, halo-CH ₂ CH ₂ - (OCH ₂ CH ₂ )^O(CO)- and halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ )i _-6 (CO)-; each R ¹⁰ is independently H or Ci- ₆ alkyl; wherein the radiolabel comprises a radionuclide selected from the group consisting of ^{1 1} C, ¹³ N, ¹⁵ 0, ¹⁸ F, ¹²³ 1, ¹²⁴ I, ¹²⁵ I, ¹³¹ I and ⁷⁷ Br; and pharmaceutically acceptable salts thereof;

For Formula VI:

X is a bond or is selected from the group consisting of C|. ₆ alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ¹⁰ )C(S)-, -S(O)N(R ¹⁰ )- and - N(R ¹⁰ )S(O) ₂ -;

Y is a bond or is selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-C,- ₆ a]kyl, perhaloCi- ₆ alkyl, Ci. ₆ alkyl, C _3-6 cycloalkyl, C _3- | ₂ cycloalkylCi- ₅ alkyl, C _6- i ₄ aryl, C ₆ -ioarylCi _-4 alkyl, heteroaryl, Ci _-5 alkoxy, H(OCH ₂ CH ₂ ) _)-6 O-, Ci _-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo- C, _-5 alkoxy, halo-Ci _-3 alkyl(OCH ₂ CH ₂ ), _-6 O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C _3- i ₂ cycloalkylC|- ₅ alkoxy, heteroarylC _2-5 alkoxy, C ₆ _i ₄ aryloxy, C ₆ .ioarylCi _-4 alkoxy and heteroaryloxy;

R ⁵ and R ⁶ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , haloC _r6 alkyl, perhaloCi- ₆ alkyl, Ci _-6 alkyl, C ₃ - ₆ cycloalkyl, C ₃ .i ₂ cycloalkylCi. ₅ alkyl, C _6- i ₄ aryl, C _6- ioarylCi _-4 alkyl, heteroaryl, Q-salkoxy, H(OCH ₂ CH ₂ ) _I-6 O-, Ci _-3 alkyl(OCH ₂ CH ₂ ) _1-6 O-, halo-Ci. ₅ alkoxy, halo-C _1-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-CH ₂ CH ₂ O-, C ₃ . ₆ cycloalkoxy, C ₃ -i ₂ cycloalkylCi. ₅ alkoxy, heteroarylC _2-5 alkoxy, C _6-14 aryloxy, C _6- ioarylC _)-4 alkoxy, heteroaryloxy, Ci. ₅ alkylNR ¹⁰ C(O)-, (C,- ₆ alkyl) ₂ NC(O)CH(Ci- ₅ alkyl)-, halo- Ci - ₆ alkylNR ¹⁰ C(O)CH(C , . ₅ alkyl)-, halo-C , - ₆ alkylOC(O)CH(C , _-5 alkyl)-, halo- C, _-5 alkylNR ¹⁰ C(O)-, C, _-5 alkylNR ¹⁰ C(O)O-, C _1-5 alkylC(O)-, Ci _-5 alkylC(O)O-, C _6- ioarylC(0)- and C ₆ -ioarylC(0)0-; or R ⁵ and R ⁶ together with the carbon atoms to which they are attached to, form a substituted or unsubstituted aromatic or non- aromatic carbocyclic or heterocyclic ring;

R ⁹ is hydrogen or is selected from the group consisting of halo, Ci _-6 alkyl, C _3-6 cycloalkyl, C ₃ .i ₂ cycloalkylCi _-5 alkyl, C _6- i ₄ aryl, C _6- ioarylCi _-4 alkyl, heteroaryl, halo-(CH ₂ CH ₂ ) _l-6 -; 1IaIo-CH ₂ CH ₂ -(OCH ₂ CH ₂ )I _-6 -, halo-CH ₂ CH ₂ - (OCH ₂ CH ₂ ) _1-6 O(CO)- and halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ), _-6 (CO)-; each R ¹⁰ is independently H or Cj- ₆ alkyl;

R ¹¹ is a hydrogen or is selected from the group consisting of halo, Ci _-6 alkyl, C ₃ . ₆ cycloalkyl, C _3- i ₂ cycloalkylCi _-5 alkyl, C _6- i ₄ aryl, C _6- ioarylCi. ₄ alkyl, heteroaryl, halo-(CH ₂ CH2)i-6-; halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _1-6 -, halo-CH ₂ CH ₂ - (OCH ₂ CH ₂ )L ₆ O(CO)- and halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _1-6 (CO)-;

provided that at least one of R ¹ to R ¹² comprises a radiolabel, as defined herein; wherein the radiolabel comprises a radionuclide selected from the group consisting of ^{1 1} C, ¹³ N, ¹⁵ O, ¹⁸ F, ¹²³ 1, ¹²⁴ I, ¹²⁵ I, ¹³¹ I and ⁷⁷ Br; and pharmaceutically acceptable salts thereof. 2. The radiolabeled compound of Claim 1 , wherein: For Formula I:

A is N or CR ¹ ; B is N or CR ² ; J is N or CR ³ ; K is N or CR ⁴ ; L is N or CR ⁵ ; M is N or CR ⁶ ; P is N; and Q is N or CR ⁸ ;

X is a bond or is selected from the group consisting of Ci- _ό alkylenyl, -C(O)-, -C(S)-, -C(O)O- and -C(S)O-; and

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , haloC,- ₆ alkyl, perhaloCi- ₆ alkyl, C, _-6 aIkyl, C ₃ - ₆ cycloalkyl, C ₃ _i ₂ cycloalkylC _1-5 alkyl, C _6-]4 aryl, C ₆ -ιoarylC| _-4 alkyl, heteroaryl, C _1-5 alkoxy, H(OCH ₂ CH ₂ ) _{I 6} O-, Ci _-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-Ci. ₅ alkoxy, halo-Ci _-3 alkyl(OCH ₂ CH ₂ ),. ₆ O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C _3-12 cycloalkylCi.5alkoxy, heteroarylC _2-5 alkoxy, C _6- i ₄ aryloxy, C _ό -ioarylCi^alkoxy, heteroaryloxy, Ci. ₅ alkylNR ¹⁰ C(O)-, (C,- ₆ alkyl) ₂ NC(O)CH(C _1-5 alkyl)-, halo- Ci- ₆ alkylNR ¹⁰ C(O)CH(Ci_ ₅ alkyl)-, halo-Ci- ₆ alkylOC(O)CH(Ci- ₅ alkyl)-, halo- Ci _-5 alkylNR ¹⁰ C(O)-, d. ₅ alkylNR ¹⁰ C(O)O-, C _1-5 alkylC(O)-, Ci _-5 alkylC(O)O-, C _6- i ₀ arylC(O)- and C _6- i ₀ arylC(O)O-; or at least one of R ¹ and R ² , R ² and R ³ , R ³ and R ⁴ , R ⁵ and R ⁶ , R ⁶ and R ⁷ , or R ⁷ and R ⁸ together with the carbon atoms to which they are attached to, form a substituted or unsubstituted aromatic or non-aromatic carbocyclic or heterocyclic ring; For Formula II:

X is a bond or is selected from the group consisting of Ci- ₆ alkylenyl, -C(O)-, -C(S)-, -C(O)O- and -C(S)O-; and

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , haloCi- ₆ alkyl, perhaloC-ealkyl, C, _-6 alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi_ ₅ alkyl, C _6- i ₄ aryl, heteroaryl, Ci _-5 alkoxy, H(OCH ₂ CH ₂ ), _-6 O-, Ci _-3 alkyl(OCH ₂ CH ₂ ), _-6 O-, halo-Ci _-5 alkoxy, halo-C,. ₃ alkyl(OCH ₂ CH ₂ ) _1-6 O-, halo-CH ₂ CH ₂ O-, C ₃ . ₆ cycloalkoxy,

C _3- i ₂ cycloalkylCi. ₅ alkoxy, heteroarylC _2-5 alkoxy, C ₆ -i ₄ aryloxy, C ₆ .ioarylCi _-4 alkoxy, heteroaryloxy, C _l-5 alkylNR ¹⁰ C(O)-, (C,- ₆ alkyl) ₂ NC(O)CH(C _1-5 alkyl)-, halo- Ci _-5 alky]NR ¹⁰ C(O)-, Ci. ₅ alkylNR ¹⁰ C(O)O-, C, _-5 alkylC(O)-, C,. ₅ alkylC(O)O-, C ₆ . ₎₀ arylC(O)- and C ₆ -ioarylC(0)0-; or at least one of R ¹ and R ² , R ² and R ³ , R ³ and R ⁴ , R ⁵ and R ⁶ , R ⁶ and R ⁷ , or R ⁷ and R ⁸ together with the carbon atoms to which they are attached to, form a substituted or unsubstituted aromatic or non-aromatic carbocyclic or heterocyclic ring; For Formula III:

Y and Y' are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-C,- ₆ alkyl, perhaloCi- ₆ alkyl, Ci- _ό alkyi, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi_ ₅ alkyl, C ₆ -i ₄ aryl, heteroaryl, C _1-5 alkoxy, H(OCH ₂ CH ₂ )i _-6 O-, C, _-3 alkyl(OCH ₂ CH ₂ ), _-6 O-, halo-C _1-5 alkoxy, halo-C _1-3 alkyl(OCH ₂ CH ₂ )i- ₆ O-, halo- CH ₂ CH ₂ O-, Cv _ό cycloalkoxy, C _3- i ₂ cycloalkylCi _-5 alkoxy, heteroarylC _2-5 alkoxy, C _ό -πaryloxy, C _6- ioarylC _1-4 alkoxy and heteroaryloxy when R ^{1 1} and R ¹² are absent;

R , R , R and R are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , haloCi- ₆ alkyl, perhaloC _r6 alkyl, Ci_ ₆ alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi_ ₅ alkyl, C _6- | ₄ aryl, heteroaryl, Ci-salkoxy, H(OCH ₂ CH ₂ )^O-, C,. ₃ alkyl(OCH ₂ CH ₂ )i- ₆ θ-, halo-C _2-5 alkoxy, halo-C _2-3 alkyl(OCH ₂ CH ₂ ) _1-6 O-, halo-CH ₂ CH ₂ O-, C ₃ _ ₆ cycloalkoxy, C _3- i ₂ cycloalkylCi. ₅ alkoxy, heteroarylC _2-5 alkoxy, C _6-14 aryloxy, C _6- ioarylCi _-4 alkoxy, heteroaryloxy, Ci _-5 alkylNR ¹⁰ C(O)-, (C,- ₆ alkyl) ₂ NC(O)CH(C _1-5 alkyl)-, halo- C ₂ - ₆ alkylNR ¹⁰ C(O)CH(Ci _-5 alkyl)-, halo-C,- ₆ alkylOC(O)CH(C, _-5 alkyl)-, halo- C _1-5 alkylNR ¹⁰ C(O)-, C _1-5 alkylNR ^I0 C(O)O-, C _1-5 alkylC(O)-, C, _-5 alkylC(O)O-, C ₆ ., ₀ arylC(O)- and C _6-10 arylC(O)O-; or at least one of R ¹ and R ² , R ² and R ³ , R ³ and R ⁴ , R ⁵ and R ⁶ , R ⁶ and R ⁷ , or R ⁷ and R ⁸ together with the carbon atoms to which they are attached to, form a substituted or unsubstituted aromatic or non-aromatic carbocyclic or heterocyclic ring; For Formula IV:

W is O or -N-X-R ⁹ ;

R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ ,

-C(O)NH ₂ , -C(S)NH ₂ , halo-C|- ₆ alkyl, perhaloC,- ₆ alkyl, Ci. ₆ alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi_ ₅ alkyl, C _6- | ₄ aryl, C _6- ioarylCi _-4 alkyl, heteroaryl, Ci.salkoxy, H(OCH ₂ CH ₂ ) _I-6 O-, C _1-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-C,. ₅ alkoxy, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C ₃ -i ₂ cycloalkylCi. ₅ alkoxy, heteroary!C ₂ - ₅ alkoxy, C _6- i ₄ aryloxy, C ₆ _ioarylCi _-4 alkoxy, heteroaryloxy, Ci _-5 alkylNR ^l0 C(O)-, (C ₁ - ₆ alkyl) ₂ NC(O)CH(C _{1 -5} alkyl)-, halo- C,- ₆ alkylNR ^l0 C(O)CH(C _1-5 alkyl)-, halo-C,- ₆ alkylOC(O)CH(C, _-5 alkyl)-, halo- C, _-5 alkylNR ^l0 C(O)-, C,. ₅ alkylNR ¹⁰ C(O)O-, C, _-5 alkylC(O)-, C _1-5 alkylC(O)O-, C _6-)0 arylC(O)- and C _6- i ₀ arylC(O)O-; or at least one of R ¹ and R ² , R ² and R ³ or R ³ and R ⁴ together with the carbon atoms to which they are attached to, form a substituted or unsubstituted aromatic or non-aromatic carbocyclic or heterocyclic ring; For Formula V:

X is a bond or is selected from the group consisting of Ci _-6 alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ^I0 )C(O)-, -N(R ^IO )C(S)-, -S(O)N(R ¹⁰ )- and - N(R ¹⁰ )S(O) ₂ -;

R ⁵ and R ⁶ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-Ci- ₆ alkyl, perhaloC _r6 alkyl, Ci _-6 alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi_ ₅ alkyl, C _6- i ₄ aryl, C _6- ioarylCi _-4 alkyl, heteroaryl, C^alkoxy, H(OCH ₂ CH ₂ ) _1-6 O-, Ci _-3 alkyl(OCH ₂ CH ₂ ) _1-6 O-, halo-C _1-5 alkoxy, halo-C, _-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C ₃ _i ₂ cycloalkylC]. ₅ alkoxy, heteroarylC _2-5 alkoxy, C _6- i ₄ aryloxy, C ₆ _ioarylCi. ₄ alkoxy, heteroaryloxy, C, _-5 alkylNR ¹⁰ C(O)-, (Ci- ₆ alkyl) ₂ NC(O)CH(C _1-5 alkyl)-, halo-Ci. ₆ alkylNR ¹⁰ C(O)CH(C _1-5 alkyl)-, halo-C,- ₆ alkylOC(O)CH(C _1-5 alkyl)-, halo- C, _-5 alkylNR ¹⁰ C(O)-, C _I-5 alkylNR ¹⁰ C(O)O-, Ci _-5 alkylC(O)-, d. ₅ alkylC(O)O-, C _6- i ₀ arylC(O)- and C _6- i ₀ arylC(O)O-; and

R ⁹ is hydrogen or is selected from the group consisting of halo, Ci _-6 alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi _-5 alkyl, C _6- i ₄ aryl, C _6- ioarylCi _-4 alkyl, heteroaryl, halo-(CH ₂ CH ₂ )i _-6 -; halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ )i _-6 -, halo-CH ₂ CH ₂ - (OCH ₂ CH ₂ ) _L6 O(CO)- and halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ), _-6 (CO)-; For Formula VI:

X is a bond or is selected from the group consisting of Ci- _ό alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ¹⁰ )C(S)-, -S(O)N(R ¹⁰ )- and - N(R ¹⁰ )S(O) ₂ -;

Y is a bond or is selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , haloCi- ₆ alkyl, perhaloCi- ₆ alkyl, C| _-6 alkyl, C ₃ . ₆ cycloalkyl, C _3- i ₂ cycloalkylCi _-5 alkyl, C _6- i ₄ aryl, C _6- ioarylCi- ₄ alkyl, heteroaryl, C _1-5 alkoxy, H(OCH ₂ CH ₂ ) _1-6 O-, C,. ₃ alkyl(OCH ₂ CH ₂ ) _1-6 O-, halo- C|. ₅ alkoxy, halo-C _1-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C _3- i ₂ cycloalkylCi- ₅ alkoxy, heteroarylC _2-5 alkoxy, C ₆ -i ₄ aryloxy, C ₆ -ioarylCi _-4 alkoxy and heteroaryloxy;

R ⁵ and R ⁶ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-Ci- ₆ alkyl, perhaloC,- ₆ alkyl, C, _-6 alkyl, C ₃ _ ₆ cycloalkyl, C _3- i ₂ cycloalkylCi _-5 alkyl, C _6- i ₄ aryl, C _6- ioarylCi- ₄ alkyl, heteroaryl, Ci _-5 alkoxy, H(OCH ₂ CH ₂ )^O-, C,. ₃ alkyl(OCH ₂ CH ₂ )i- ₆ O-, halo-C,. ₅ alkoxy, halo-Ci _-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C^^cycloalkylCi^alkoxy, heteroarylC _2-5 alkoxy, C _6- i ₄ aryloxy, C _6- ioarylCi _-4 alkoxy, heteroaryloxy, C _)-5 alkylNR ¹⁰ C(O)-, (Ci- ₆ alkyl) ₂ NC(O)CH(Ci _-5 alkyl)-, halo- C,- ₆ alkylNR ¹⁰ C(O)CH(Ci _-5 alkyl)-, halo-Ci- ₆ alkylOC(O)CH(Ci _-5 alkyl)-, halo- C, _-5 alkylNR ¹⁰ C(O)-, Ci _-5 alkylNR ¹⁰ C(O)O-, d- ₅ alkylC(O)-, C, _-5 alkylC(O)O-, C ₆ . ₁₀ arylC(O)- and C _{6- 10} ary IC(O)O-;

R ⁹ is hydrogen or is selected from the group consisting of halo, Ci _-6 alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylC]- ₅ alkyl, C _6- i ₄ aryl, C _6- ioarylCi _-4 alkyl, heteroaryl, halo-(CH ₂ CH ₂ ) _1-6 -; halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _1-6 -, halo-CH ₂ CH ₂ - (OCH ₂ CH ₂ ) _1-6 O(CO)- and halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ), _-6 (CO)-; and

R ¹¹ is absent, a hydrogen or is selected from the group consisting of halo, Ci _-6 alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi _-5 alkyl, C _6- i ₄ aryl, C _6- ioarylCi- ₄ alkyl, heteroaryl, halo-(CH ₂ CH ₂ ) _I-6 -; halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ )i _-6 -, halo-CH ₂ CH ₂ - (OCH ₂ CH ₂ ) _L6 O(CO)- and halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ), _-6 (CO)-; wherein the radiolabel comprises a radionuclide selected from the group consisting of ^{1 1} C, ¹³ N, ¹⁵ O, ¹⁸ F, ¹²³ 1, ¹²⁴ I, ¹²⁵ I, ¹³¹ I and ⁷⁷ Br; and pharmaceutically acceptable salts thereof.

3. The compound of Claim 2, wherein:

For Formula I:

A is N or CR ¹ ; B is N or CR ² ; J is N or CR ³ ; K is N or CR ⁴ ; L is N or CR ⁵ ; M is N or CR ⁶ ; P is N or CR ⁷ ; and Q is N or CR ⁸ , provided that no more than two of A, B, J, K, L, M, P and Q can be N;

X is a bond or is selected from the group consisting of Ci _-6 alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ^IO )C(S)-, -S(O)N(R ¹⁰ )- and - N(R ¹⁰ )S(O) ₂ -; and

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-C,- ₆ alkyl, perhaloC,- ₆ alkyl, C,. ₆ alkyl, C ₃ _ ₆ cycloalkyl, C _3- i ₂ cycloalkylCi_ ₅ alkyl, heteroarylC _2-5 alkoxy, C _ό -uaryl, C _6-10 aryICi _-4 alkyl, heteroaryl, C _1-5 alkoxy, H(OCH ₂ CH ₂ ) _I-6 O- and C _1-3 alkyl(OCH ₂ CH ₂ ), _-6 O-; For Formula II:

X is a bond or is selected from the group consisting of C] _-6 alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ¹⁰ )C(S)-, -S(O)N(R ¹⁰ )- and - N(R ¹⁰ )S(O) ₂ -; and

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , haloC,- ₆ alkyl, perhaloCi- ₆ alkyl, C _1-6 alkyl, C ₃ . ₆ cycloalkyl, C _3- i ₂ cycloalkylCι _-5 alkyl, heteroarylC ₂ - ₅ alkoxy, C _6-14 aryl, C _6- i ₀ arylC _1-4 alkyl, heteroaryl, Ci _-5 alkoxy, H(OCH ₂ CH ₂ ), _-6 O- and C ₁ . ₃ alkyl(OCH ₂ CH ₂ )i- ₆ O-; For Formula HI:

Y and Y' are each independently a bond or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , - C(S)NH ₂ , haloCi- ₆ alkyl, perhaloC _r6 alkyl, C _1-6 alkyl, C ₃ . ₆ cycloalkyl, C _3- i ₂ cycloalkylCi. ₅ alkyl, C ₆ .i ₄ aryl, heteroaryl, Ci.salkoxy, H(OCH ₂ CH ₂ )^O-, Ci _-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-d _-5 alkoxy, halo-C, _-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C ₃ -i ₂ cycloalkylCi. ₅ alkoxy, heteroarylC ₂ . ₅ alkoxy, C _6-14 aryloxy, C _6- ioarylCi _-4 alkoxy and heteroaryloxy when R ¹¹ and R ¹² are absent; and

R , R , R and R are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ ,

-C(O)NH ₂ , -C(S)NH ₂ , halo-C _r6 alkyl, perhaloC _r6 alkyl, Ci _-6 alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi _-5 alkyl, heteroarylC _2-5 alkoxy, C _6- i ₄ aryl, C _6- ioarylCi _-4 alkyl, heteroaryl, d _-5 alkoxy, H(OCH ₂ CH ₂ ) _{1 -6} O- and C,_ ₃ alkyl(OCH ₂ CH ₂ )i. ₆ O-; For Formula IV:

W is O or -N-X-R ⁹ ;

X is a bond or is selected from the group consisting of Ci _-6 alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ¹⁰ )C(S)-, -S(O)N(R ¹⁰ )- and - N(R ¹⁰ )S(O) ₂ -;

Y and Y' are each independently a bond or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , - C(S)NH ₂ , halo-Ci- ₆ alkyl, perhaloCi- ₆ alkyl, Ci _-6 alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi _-5 alkyl, C _6- i ₄ aryl, heteroaryl, Ci-salkoxy, H(OCH ₂ CH ₂ ) _I-6 O-, C _I-3 alkyl(OCH ₂ CH ₂ ),. ₆ O-, halo-C _1-5 alkoxy, halo-C _1-3 alkyl(OCH ₂ CH ₂ ), _-6 O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C _3- i ₂ cycloalkylCi. ₅ alkoxy, heteroarylC _2-5 alkoxy, C _6- i ₄ aryloxy, C _ό -ioarylCi^alkoxy and heteroaryloxy when R ¹¹ and R ¹² are absent; and

R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-Ci- ₆ alkyl, perha]oC _r6 alkyl, Ci _-6 alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi- ₅ alkyl, heteroarylC _2-5 alkoxy, C ₆ -i ₄ aryl, C ₆ -ioarylCi_ ₄ alkyl, heteroaryl, C^alkoxy, H(OCH ₂ CH ₂ ) _{I -6} O- and Ci _-3 alkyl(OCH ₂ CH ₂ )i _-6 O-; For Formula V:

X is a bond or is selected from the group consisting of Ci _-6 alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ¹⁰ )C(S)-, -S(O)N(R ¹⁰ )- and - N(R ¹⁰ )S(O) ₂ -; and

R ⁵ and R ⁶ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-d-ealkyl, perhaloC _r6 alkyl, Chalky., C ₃ . ₆ cycloalkyl, C _3- i ₂ cycloalkylCi- ₅ alkyl, heteroarylC _2- salkoxy, C _6-14 aryl, C _6- ioarylC _1-4 alkyl, heteroaryl, Ci _-5 alkoxy, H(OCH ₂ CH ₂ ) _L6 O- and C i _-3 alkyl (OCH ₂ CH ₂ ) _I-6 O-; For Formula VI:

X is a bond or is selected from the group consisting of Ci _-6 alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ^IO )C(S)-, -S(O)N(R ¹⁰ )- and - N(R'°)S(O) ₂ -;

Y is a bond or is selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , haloC,- ₆ alkyl, perhaloC,- ₆ alkyl, Ci _-6 alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi- ₅ alkyl, C _6- i ₄ aryl, C ₆ -ioarylCi- ₄ alkyl, heteroaryl, Ci _-5 alkoxy, H(OCH ₂ CH ₂ ), _-6 O-, C i_ ₃ alkyl (OCH ₂ CH ₂ ) , _-6 O-, halo- C,. ₅ alkoxy, halo-C _1-3 alkyl(OCH ₂ CH ₂ )i. ₆ O-, halo-CH ₂ CH ₂ O-, C ₃ . ₆ cycloalkoxy, C ₃ _i ₂ cycloalkylC _1-5 alkoxy, heteroarylC ₂ - ₅ alkoxy, C _6- i ₄ aryloxy, C ₆ -ioarylCi _-4 alkoxy and heteroaryloxy when R ¹¹ is absent; and

R ⁵ and R ⁶ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-Ci- ₆ alkyl, perhaloCi- ₆ alkyl, d _-6 alkyl, C _3-6 cycloalkyl, C ₃ -i ₂ cycloalkylCi- ₅ alkyl, heteroarylC ₂ _ ₅ alkoxy, C _6- i ₄ aryl, heteroaryl, C| _-5 alkoxy, H(OCH ₂ CH ₂ ), _-6 0- and Ci _-3 alkyl(OCH ₂ CH ₂ ),. ₆ O-; wherein the radiolabel comprises a radionuclide selected from the group consisting of ^{1 1} C, ¹³ N, ¹⁵ O, ¹⁸ F, ¹²³ 1, ¹²⁴ I, ¹²⁵ I, ¹³¹ I and ⁷⁷ Br; and pharmaceutically acceptable salts thereof.

4. The compound of Claim 1 , wherein: For Formula I:

A is N or CR ¹ ; B is N or CR ² ; J is N or CR ³ ; K is N or CR ⁴ ; L is N or CR ⁵ ; M is N or CR ⁶ ; P is N or CR ⁷ ; and Q is N or CR ⁸ , provided that no more than two of A, B, J, K, L, M, P and Q can be N;

X is a bond or is selected from the group consisting of -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ¹⁰ )C(S)-, -S(O)N(R ¹⁰ )- and - N(R ¹⁰ )S(O) ₂ -; and

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently hydrogen or are each independently selected from the group consisting of halo-C| _-5 alkoxy, halo-C _1-3 alkyl(OCH ₂ CH ₂ ) , _-6 O-, halo-CH ₂ CH ₂ O-, halo-C, - ₆ alkylNR' ⁰ C(O)CH(C , . ₅ alkyl)-, halo-Ci- ₆ alkylOC(O)CH(C, _-5 alkyl)- and halo-C _1-5 alkylNR ^l0 C(O)-; For Formula II:

X is a bond or is selected from the group consisting of Ci. ₆ alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ¹⁰ )C(S)-, -S(O)N(R ¹⁰ )- and - N(R ¹⁰ JS(O) ₂ -; and

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently hydrogen or are each independently selected from the group consisting of halo-C ₂ . ₅ alkoxy,

halo-Ci _ ₃ alkyl (OCH ₂ CH ₂ ) , . ₆ O-, halo-CH ₂ CH ₂ O-, halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) , _-6 O-, halo-Ci- ₆ alkylNR ^l0 C(O)CH(Ci _-5 alkyl)-, halo-Ci- ₆ alkylOC(O)CH(C, _-5 alkyl)- and halo-C, . ₅ alkylNR ¹⁰ C(O)-; For Formula III:

Y and Y' are each independently a bond or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , - C(S)NH ₂ , haloCi- ₆ alkyl, perhaloC _r6 alkyl, C _h alky!, C _3-6 cycloalkyl, C ₃ -i ₂ cycloalkylCi- ₅ alkyl, C ₆ -i ₄ aryl, C _6- i ₀ arylCi. ₄ alkyl, heteroaryl, Ci_ ₅ alkoxy, H(OCH ₂ CH ₂ ) _1-6 O-, Ci_ ₃ alkyl(OCH ₂ CH ₂ ) _{1 -6} O-, halo-C _1-5 alkoxy, halo-C, _-3 alkyl(OCH ₂ CH ₂ ) _I-6 O-, halo-CH ₂ CH ₂ O-, C ₃ . ₆ cycloalkoxy, heteroaryIC _2-5 alkoxy, C _6- i ₄ aryloxy, C _6- ioarylCi _-4 alkoxy and heteroaryloxy when R ¹¹ and R ¹² are absent; and

R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently hydrogen or are each independently selected from the group consisting of halo-Ci.salkoxy, halo-Ci _-3 alkyl(OCH ₂ CH ₂ ),. ₆ O-, halo-CH ₂ CH ₂ O-, FCH ₂ CH ₂ -(OCH ₂ CH ₂ ) _1-6 O-, haloCi-6alkylNR ¹⁰ C(O)CH(Ci. ₅ alkyl)-, halo-Ci- ₆ alkylOC(O)CH(Ci.5alkyl)- and halo-Ci _-5 alkylNR ¹⁰ C(O)-; For Formula IV:

W is O or -N-X-R ⁹ ;

X is a bond or is selected from the group consisting of Ci _-6 alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ¹⁰ )C(S)-, -S(O)N(R ¹⁰ )- and - N(R ¹⁰ )S(O) ₂ -;

Y and Y' are each independently a bond or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , - C(S)NH ₂ , halo-C ₂ - ₆ alkyl, perhaloC,- ₆ alkyl, C^alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi. ₅ alkyl, C _6- i ₄ aryl, C^ioarylC^alkyl, heteroaryl, Ci _-5 alkoxy, H(OCH ₂ CH ₂ ), _-6 O-, Ci _-3 alkyl(OCH ₂ CH ₂ ), _-6 O-, halo-C, _-5 alkoxy, halo-Ci _-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C ₃ .i ₂ cycloalkylCi. ₅ alkoxy, heteroarylC _2-5 alkoxy, C _6- i ₄ aryloxy, C _6- ioarylCi _-4 alkoxy and heteroaryloxy when R ¹¹ and R ¹² are absent; and

R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or are each independently selected from the group consisting of halo-Ci _-5 alkoxy, halo-C , _-3 alkyl (OCH ₂ CH ₂ ) , _-6 O-, halo-CH ₂ CH ₂ O-, halo-C , - ₆ alkylNR ¹⁰ C(O)CH(C , . ₅ alkyl)-, halo-CrβalkylOCCO^HCQ.salkyl)- and halo-C. ₅ alkylNR ¹⁰ C(O)-;

For Formula V:

X is a bond or is selected from the group consisting of Ci- ₆ alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ¹⁰ )C(S)-, -S(O)N(R ¹⁰ )- and - N(R ¹⁰ )S(O) ₂ -; and

R ⁵ and R ⁶ are each independently hydrogen or are each independently selected from the group consisting of halo-Ci.salkoxy, halo-Ci- ₃ alkyl(OCH ₂ CH ₂ ) _1-6 O-, halo-CH ₂ CH ₂ O-, halo-C,- ₆ alkylNR ¹⁰ C(O)CH(C,. salkyl)-, ha]o-C,- ₆ alkylOC(O)CH(Ci _-5 alkyl)- and halo-Ci _-5 alkylNR ¹⁰ C(O)-; For Formula VI:

X is a bond or is selected from the group consisting of Ci _-6 alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ^l0 )C(O)-, -N(R ¹⁰ )C(S)-, -S(O)N(R ¹⁰ )- and - N(R ¹⁰ )S(O) ₂ -;

Y is a bond or is selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-C _h alky], perhaloC _r6 alkyl, Ci- ₆ alkyl, C _3-6 cycloalkyl, C ₃ .i ₂ cycloalkylCi- ₅ alkyl, C ₆ -i ₄ aryl, heteroaryl, d _-5 alkoxy, H(OCH ₂ CH ₂ ) _I-6 O-, d _-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo- Ci _-5 alkoxy, halo-Ci _-3 alkyl(OCH ₂ CH ₂ ), _-6 O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C _3- i ₂ cycloalkylCi _-5 alkoxy, heteroarylC _2-5 alkoxy, C _ό -πaryloxy, C _6- ioarylCi _-4 alkoxy and heteroaryloxy when R ¹¹ is absent; and

R ⁵ and R ⁶ are each independently hydrogen or are each independently selected from the group consisting of halo-C _1-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-CH ₂ CH ₂ O-, halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ )i _-6 O-, halo-Ci- ₆ alkylNR ¹⁰ C(O)CH(C, _-5 alkyl)-, halo-Ci- ₆ alkylOC(O)CH(C _1-5 alkyl)- and halo-Ci _-5 alkylNR ¹⁰ C(O)-; wherein the radiolabel comprises a radionuclide selected from the group consisting of ¹¹ C, ¹³ N, ¹⁵ O, ¹⁸ F, ¹²³ 1, ¹²⁴ I, ¹²⁵ I, ¹³¹ I and ⁷⁷ Br; and pharmaceutically acceptable salts thereof.

5. The compound of Claim 1 , wherein: For Formula I:

A is N or CR ¹ ; B is N or CR ² ; J is N or CR ³ ; K is N or CR ⁴ ; L is N or CR ⁵ ; M is N or CR ⁶ ; P is N or CR ⁷ ; and Q is N or CR ⁸ , provided that no more than two of A, B, J, K, L, M, P and Q can be N;

X is a bond or is selected from the group consisting of Ci _-6 alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ^l0 )C(O)-, -N(R ^IO )C(S)-, -S(O)N(R ¹⁰ )- and - N(R ^l0 )S(O) ₂ -; and

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently hydrogen or are each independently selected from the group consisting of C _3-6 cycloalkoxy, C _3- i ₂ cycloalkylCi _-5 alkoxy, heteroarylC _2-5 alkoxy, C _6- i ₄ aryloxy, C ₆ -ioarylCi _-4 alkoxy, heteroaryloxy, Ci _-5 alkylNR ¹⁰ C(O)-, (Ci- ₆ alkyl) ₂ NC(O)CH(C, _-5 alkyl)-, C _1-5 alkylNR ^l0 C(O)O-, Ci _-5 alkylC(O)-, Ci _-5 alkylC(O)O-, C _6-l0 arylC(O)- and C _6- , ₀ arylC(O)O-; For Formula II:

X is a bond or is selected from the group consisting of -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ¹⁰ )C(S)-, -S(O)N(R ¹⁰ )- and - N(R ¹⁰ )S(O) ₂ -; and

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently hydrogen or are each independently selected from the group consisting of C _3-6 cycloalkoxy, C ₃ .i ₂ cycloalkylC _1-5 alkoxy, heteroarylC ₂ _ ₅ alkoxy, C _6- i ₄ aryloxy, heteroaryloxy, C i _-5 alkylNR ¹⁰ C(O)-, (C,- ₆ alkyl) ₂ NC(O)CH(C, _-5 alkyl)-, Q- ₅ alkylNR ¹⁰ C(O)O-, C, _-5 alkylC(O)-, d _-5 alkylC(O)O-, C _6- , _o ary IC(O)- and C _6- ioarylC(0)0-; For Formula III:

Y and Y' are each independently a bond or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , - C(S)NH ₂ , haloCi- ₆ alkyl, perhaloCi- ₆ alkyl, C _!-6 alkyl, C _3-6 cycloalkyl, C _3-12 cycloalkylC _1-5 alkyl, C _6- i ₄ aryl, C ₆ -ioarylCi _-4 alkyl, heteroaryl, Ci-salkoxy, H(OCH ₂ CH ₂ )I _-6 O-, Ci _-3 alkyl(OCH ₂ CH ₂ ), _-6 O-, halo-C _2-5 alkoxy, halo-Ci _-3 alkyl(OCH ₂ CH ₂ ), _-6 O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C _3- i ₂ cycloalkylCi.. ₅ alkoxy, heteroarylC _2-5 alkoxy, C ₆ -i ₄ aryloxy, and heteroaryloxy when R ¹¹ and R ¹² are absent; and

R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently hydrogen or are each independently selected from the group consisting of C _3-6 cycloalkoxy, C _3- i ₂ cycloalkylC _1-5 alkoxy, heteroarylC ₂ - ₅ alkoxy, C _6- i ₄ aryloxy, C ₆ -ioarylCi _-4 alkoxy, heteroaryloxy, Ci- ₅ alkylNR ¹⁰ C(O)-, (Ci- ₆ alkyl) ₂ NC(O)CH(C, _-5 alkyl)-, Ci_ ₅ alkylNR ¹⁰ C(O)O-, C _{1 -5} alkylC(O)-, C, _-5 alkylC(O)O-, C _6- i ₀ arylC(O)- and C _6-I0 arylC(O)O-; For Formula IV:

W is O or -N-X-R ⁹ ;

X is a bond or is selected from the group consisting of Ci _-6 alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ¹⁰ )C(S)-, -S(O)N(R ¹⁰ )- and - N(R ¹⁰ )S(O) ₂ -;

Y and Y' are each independently a bond or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , - C(S)NH ₂ , halo-C ₂ - ₆ alkyl, perhaloC _r6 alky], C,. ₆ alkyl, C ₃ . ₆ cycloalkyl, C _3- i ₂ cycloalkylCi- ₅ alkyl, C _6- i ₄ aryl, C ₆ -ioarylCi _-4 alkyl, heteroaryl, Ci.salkoxy, H(OCH ₂ CH ₂ ),. ₆ O-, C _I-3 alkyl(OCH ₂ CH ₂ )ι_ ₆ O-, halo-Ci_ ₅ alkoxy, halo-C _! - ₃ alkyI(OCH ₂ CH ₂ )i _-6 O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C _3- i ₂ cycloalkylCi- ₅ alkoxy, heteroarylC ₂ _ ₅ alkoxy, C ₆ -i ₄ aryloxy, and heteroaryloxy when R ¹¹ and R ¹² are absent; and

R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or are each independently selected from the group consisting of C _3-6 cycloalkoxy, C ₃ _i ₂ cycloalkylCi _-5 alkoxy, heteroarylC ₂ _ ₅ alkoxy, Cβ-πaryloxy, C _6- ioarylCi _-4 alkoxy, heteroaryloxy, Ci- ₅ alkylNR ¹⁰ C(O)-, (Ci- ₆ alkyl) ₂ NC(O)CH(C, _-5 alkyl)-, C,. ₅ alkylNR ^l0 C(O)O-, C _1-5 alkylC(O)-, Ci _-5 alkylC(O)O-, C _6-]0 arylC(O)- and C ₆ .i ₀ arylC(O)O-; For Formula V:

X is a bond or is selected from the group consisting of Q^alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ¹⁰ )C(S)-, -S(O)N(R ¹⁰ )- and - N(R ¹⁰ )S(O) ₂ -; and

R ⁵ and R ⁶ are each independently hydrogen or are each independently selected from the group consisting of C _3-6 cycloalkoxy, C _3- i ₂ cycloalkylCi- ₅ alkoxy, heteroarylC _2-5 alkoxy, C _6- i ₄ aryloxy, C _6- ioarylCi _-4 alkoxy, heteroaryloxy, Ci- ₅ alkylNR ¹⁰ C(O)-, (C,- ₆ alkyl) ₂ NC(O)CH(Ci _-5 alkyl)-, Ci _-5 alkylNR ¹⁰ C(O)O-, C, _-5 alkylC(O)-, C, _-5 alkylC(O)O-, C _6-10 arylC(O)- and C ₆ . ₁₀ arylC(O)O-; For Formula VI:

X is a bond or is selected from the group consisting of Ci _-6 alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ^1O )C(S)-, -S(O)N(R ¹⁰ )- and - N(R'°)S(O) ₂ - _;

Y is a bond or is selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-C ₂ - ₆ alkyl, perhaloCi- ₆ alkyl, C| _-6 alkyl, C _3-6 cycloalkyl, C _3-12 cycloalkylCi _-5 alkyl, C _6-)4 aryl, C ₆ .i ₀ arylCi _-4 alkyl, heteroaryl, C,. ₅ alkoxy, H(OCH ₂ CH ₂ ) _1-6 0-, Ci. ₃ alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-

d. ₅ alkoxy, halo-Ci- ₃ alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-CH ₂ CH ₂ O-, C _3-6 CyClOaIkOXy, C ₃ .i ₂ cycloalkylCi- ₅ alkoxy, heteroarylC _2-5 alkoxy, C _6-]4 aryloxy, C _6- ioarylCi _-4 alkoxy and heteroaryloxy when R ^{1 1} is absent; and

R ⁵ and R are each independently hydrogen or are each independently selected from the group consisting of C _3-6 cycloalkoxy, C ₃ .i ₂ cycloalkylCi. ₅ alkoxy, heteroarylC ₂ - ₅ alkoxy, C _6-]4 aryloxy, C _6- ioarylCi_ ₄ alkoxy, heteroaryloxy, Q- ₅ alkylNR ¹⁰ C(O)-, (Ci- ₆ alkyl) ₂ NC(O)CH(Ci _-5 alkyl)-, C, _-5 alkylNR ¹⁰ C(O)O-, C _)-5 alkylC(O)-, C _1-5 alkylC(O)O-, C _6-10 arylC(O)- and C ₆ .i ₀ arylC(O)O-; wherein the radiolabel comprises a radionuclide selected from the group consisting of ¹¹ C, ¹³ N, ¹⁵ 0, ¹⁸ F, ¹²³ 1, ¹²⁴ I, ¹²⁵ I, ¹³¹ I and ⁷⁷ Br; and pharmaceutically acceptable salts thereof.

6. The radiolabeled compound of Claim 1 wherein: For Formula I and Formula II:

X is a bond or is selected from the group consisting of Ci_ ₆ alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ¹⁰ )C(S)-, -S(O)N(R ¹⁰ )- and - N(R ¹⁰ )S(O) ₂ -;

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-C,- ₆ alkyl, perhaloCi- ₆ alkyl, C,. ₆ alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi _-5 alkyl, Cβ πaryl, C _6- ioarylC]. ₄ alkyl, heteroaryl, C,. ₅ alkoxy, H(OCH ₂ CH ₂ ), _-6 O-, C,. ₃ alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-Ci. ₅ alkoxy, halo-Ci- ₃ alkyl(OCH ₂ CH ₂ ),. ₆ O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C ₃ -i ₂ cycloalkylCi _-5 alkoxy, heteroarylC _2-5 alkoxy, C ₆ _i ₄ aryloxy, C _6- ioarylCi _-4 alkoxy, heteroaryloxy, C, _-5 alkylNR ¹⁰ C(O)-, (Cr ₆ alkyl) ₂ NC(O)CH(C, _-5 alkyl)-, halo-C,. ₆ alkylNR ¹⁰ C(O)CH(Ci _-5 alkyl)-, halo-C,- ₆ alkylOC(O)CH(Ci _-5 alkyl)-, halo- C, _-5 alkylNR ¹⁰ C(O)-, Ci _-5 alkylNR ¹⁰ C(O)O-, Ci _-5 alkylC(O)-, Ci _-5 alkylC(O)O-, C _6- i ₀ arylC(O)- and C _6- ioarylC(0)0-; or at least one of R ¹ and R ² , R ² and R ³ , R ³ and R ⁴ , R ⁵ and R ⁶ , R ⁶ and R ⁷ , or R ⁷ and R ⁸ together with the carbon atoms to which they are attached to, form a substituted or unsubstituted aromatic or non-aromatic carbocyclic or heterocyclic ring; provided that at least any two of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are hydrogens;

R ⁹ is hydrogen or is selected from the group consisting of halo, Ci- ₆ alkyl, C _3-6 cycloalkyl, C ₃ .i ₂ cycloalkylCi _-5 alkyl, C ₆ _i ₄ aryl, C ₆ -ioarylCi _-4 alkyl, heteroaryl, 1IaIo(CH ₂ CH ₂ ), *-; haloCH ₂ CH ₂ -(OCH ₂ CH ₂ ) , ^- , haloCH ₂ CH ₂ -(OCH ₂ CH ₂ ) i . ₆ O(CO)- and haloCH ₂ CH ₂ -(OCH ₂ CH ₂ ),. ₆ (CO)-; and each R ¹⁰ is independently H or Ci- ₆ alkyl; For Formula III:

Y and Y' are each independently a bond or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , - C(S)NH ₂ , haloC _r6 alkyl, perhaloC]- ₆ alkyl, C _1-6 alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi- ₅ alkyl, C ₆ -i ₄ aryl, C _6- ioarylCi _-4 alkyl, heteroaryl, Ci.salkoxy, H(OCH ₂ CH ₂ ) _I-6 O-, Ci salkyKOCHzCH^ _Lδ O-, halo-C, _-5 alkoxy, halo-Ci. ₃ alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C ₃ .i ₂ cycloalkylCi _-5 alkoxy, heteroarylC _2-5 alkoxy, C _6- i ₄ aryloxy, and heteroaryloxy when R ¹¹ and R ¹² are absent; and

R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-Ci- ₆ alkyl, perhaloCi- ₆ alkyl, C _h alky!, C _3-6 cycloalkyl, C ₃ _i ₂ cycloalkylCi. ₅ alkyl, C ₆ _i ₄ aryl, C ₆ -ioarylC _1-4 alkyl, heteroaryl, C^alkoxy, H(OCH ₂ CH ₂ ) _I-6 O-, C,. ₃ alkyl(OCH ₂ CH ₂ ), _-6 O-, halo-C _1-5 alkoxy, halo-Ci _-3 alkyl(OCH ₂ CH ₂ ) _I-6 O-, halo-CH ₂ CH ₂ O-, C ₃ . ₆ cycloalkoxy, Ca.^cycloalkylQ-salkoxy, heteroarylC _2-5 alkoxy, C _6-1 4aryloxy, C _6- ioarylCi _-4 alkoxy, heteroaryloxy, Ci. ₅ alkylNR ¹⁰ C(O)-, (Ci- ₆ alkyl) ₂ NC(O)CH(Ci _-5 alkyl)-, haloC,- ₆ alkylNR ¹⁰ C(O)CH(Ci _-5 alkyl)-, haloC|- ₆ alkylOC(O)CH(Ci _-5 alkyl)-, halo- C _1-5 alkylNR ^l0 C(O)-, Ci. ₅ alkylNR ¹⁰ C(O)O-, Ci. ₅ alkylC(O)-, Ci _-5 alkylC(O)O-, C _6- i ₀ arylC(O)- and C _6- i ₀ arylC(O)O-; or at least one of R ¹ and R ² , R ² and R ³ , R ³ and R ⁴ , R ⁵ and R ⁶ , R ⁶ and R ⁷ , or R ⁷ and R ⁸ together with the carbon atoms to which they are attached to, form a substituted or unsubstituted aromatic or non-aromatic carbocyclic or heterocyclic ring; provided that at least any two of R ⁵ , R ⁶ , R ⁷ and R ⁸ are hydrogens;

R ⁹ is hydrogen or is selected from the group consisting of halo, Ci- ₆ alkyl, C ₃ . ₆ cycloalkyl, C _3- i ₂ cycloalkylCi- ₅ alkyl, C ₆ _i ₄ aryl, C _6-1 oarylCi- ₄ alkyl, heteroaryl, halo(CH ₂ CH ₂ ) _1-6 -; halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _1-6 -, halo-CH ₂ CH ₂ - (OCH ₂ CH ₂ ) _I-6 O(CO)- and halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ )i _-6 (CO)-; and each R ¹⁰ is independently H or C|- ₆ alkyl;

For Formula IV:

W is O or -N-X-R ⁹ ;

X is a bond or is selected from the group consisting of Ci _-6 alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ¹⁰ )C(S)-, -S(O)N(R ¹⁰ )- and - N(R ¹⁰ )S(O) ₂ -;

Y and Y' are each independently a bond or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹ , -C(O)NH ₂ , - C(S)NH ₂ , halo-Ci- ₆ alkyl, perhaloC,- ₆ alkyl, C _]-6 alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi- ₅ alkyl, C _ό -uaryl, C _6- ioarylCi _-4 alkyl, heteroaryl, Ci.salkoxy, H(OCH ₂ CH ₂ ) I _-6 O-, C, _-3 alkyl(OCH ₂ CH ₂ ) _1-6 O-, halo-Ci _-5 alkoxy, halo-Ci _-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C _3- i ₂ cycloalkylCi- ₅ alkoxy, heteroarylC _2-5 alkoxy, C _6- ι ₄ aryloxy, and heteroaryloxy when R ^{1 1} and R ¹² are absent; and

R ¹ , R , R ³ and R ⁴ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-C _r6 alkyl, perhalod- ₆ alkyl, C _1-6 alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi. ₅ alkyl, C ₆ -i ₄ aryl, heteroaryl, Ci-salkoxy, H(OCH ₂ CH ₂ )I _-6 O-, Ci _-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-C, _-5 alkoxy, halo-Ci _-3 alkyl(OCH ₂ CH ₂ ) ₁ . ₆ O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C ₃ _i ₂ cycloalkylCi- ₅ alkoxy, heteroarylC ₂ . ₅ alkoxy, C _6- i ₄ aryloxy, C _6- ioarylCi- ₄ alkoxy, heteroaryloxy, C, _-5 alkylNR ¹⁰ C(O)-, (Ci- ₆ alkyl) ₂ NC(O)CH(C, _-5 alkyl)-, haloC i - ₆ alkylNR ¹⁰ C(O)CH(C , . ₅ alkyl)-, haloC , - ₆ alkylOC(O)CH(C , _-5 alkyl)-, haloC,. ₅ alkylNR ¹⁰ C(O)-, C, _-5 alkylNR ^l0 C(O)O-, Ci. ₅ alkylC(O)-, C _1-5 alkylC(O)O-, C _6- i ₀ arylC(O)- and C _6-10 arylC(O)O-; or at least one of R ¹ and R ² , R ² and R ³ or R ³ and R ⁴ together with the carbon atoms to which they are attached to, form a substituted or unsubstituted aromatic or non-aromatic carbocyclic or heterocyclic ring; provided that at least any two of R ¹ , R ² , R ³ and R ⁴ are hydrogens;

R ⁹ is hydrogen or is selected from the group consisting of halo, Ci _-6 alkyl, C _3-6 cycloalkyl, C^πcycloalkylCi-salkyl, C _6- i ₄ aryl, C _6- ioarylCi _-4 alkyl, heteroaryl, ImIo-(CH ₂ CH ₂ ) _L6 -; halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ )i _-6 -, halo-CH ₂ CH ₂ - (OCH ₂ CH ₂ )I _-6 O(CO)- and halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ), _-6 (CO)-; and each R ¹⁰ is independently H or Ci- ₆ alkyl; For Formula V:

X is a bond or is selected from the group consisting of Ci. ₆ alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ^1O )C(S)-, -S(O)N(R ¹⁰ )- and - N(R ^l0 )S(O) ₂ -; and

R ⁵ and R ⁶ are each independently each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-C,- ₆ alkyl, perhaloC,- ₆ alkyl, C _1-6 alkyl, C _3-6 cycloalkyl, C ₃ .i ₂ cycloalkylC]_ ₅ alkyl, C _6- i ₄ aryl, C _6-) oarylCi _-4 alkyl, heteroaryl, C _I-5 alkoxy, H(OCH ₂ CH ₂ ) , _-6 O-, C i _-3 alkyl (OCH ₂ CH ₂ ) _1-6 O-, halo-Ci_ ₅ alkoxy, halo-Ci _-3 alkyl(OCH ₂ CH ₂ )i_ ₆ O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C _3- i ₂ cycloalkylCi _-5 alkoxy, heteroarylC _2-5 alkoxy, C _6- i ₄ aryloxy, C ₆ _ioarylC] _-4 alkoxy, heteroaryloxy, C,. ₅ alkylNR ¹⁰ C(O)-, (Ci- ₆ alkyl) ₂ NC(O)CH(Ci _-5 alkyl)-, halo- C,- ₆ alkylNR ¹⁰ C(O)CH(Ci _-5 alkyl)-, halo- C _1-5 alkylNR ¹⁰ C(O)-, Ci _-5 alkylNR ¹⁰ C(O)O-, C _1-5 alkylC(O)-, C _{1 -5} alkylC(O)O-, C _6-10 arylC(O)- and C _6-10 arylC(O)O-;

R ⁹ is hydrogen or is selected from the group consisting of halo, Ci _-6 alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylC _1-5 alkyl, C _6- i ₄ aryl, C _6- ioarylCi _-4 alkyl, heteroaryl, halo-(CH ₂ CH ₂ ) _I-6 -; halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ )i^-, halo-CH ₂ CH ₂ - (OCH ₂ CHz) _1-6 O(CO)- and halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _I-6 (CO)-; and each R ¹⁰ is independently H or Ci- ₆ alkyl; For Formula VI:

X is a bond or is selected from the group consisting of Ci_ ₆ alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ¹⁰ )C(S)-, -S(O)N(R ¹⁰ )- and - N(R ¹⁰ )S(O) ₂ -;

Y is a bond or is selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , haloCi- ₆ alkyl, perhaloC,- ₆ alkyl, Ci _-6 alkyl, C ₃ _6cycloalkyl, C3.i ₂ cycloalkylCi.5alkyl, C _6- i ₄ aryl, C ₆ -ioarylCi-4alkyl, heteroaryl, Ci. ₅ alkoxy, H(OCH ₂ CH ₂ ), _-6 O-, Ci _-3 alkyl(OCH ₂ CH ₂ )i. ₆ O-, halo- C _2-5 alkoxy, halo-C _{t -3} alkyl(OCH ₂ CH ₂ ),. ₆ O-, halo-CH ₂ CH ₂ O-, C ₃ . ₆ cycloalkoxy, C _3- i ₂ cycloalkylCi _-5 alkoxy, heteroarylC ₂ - ₅ alkoxy, C ₆ _i4aryloxy, C ₆ _ioarylCi _-4 alkoxy and heteroaryloxy when R ¹¹ is absent; and

R ⁵ and R ⁶ are each independently each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-C,- ₆ alkyl, perhaloC,- ₆ alkyl, C _1-6 alkyl, C ₃ . ₆ cycloalkyl, C ₃ .i ₂ cycloalkylCi _-5 alkyl, C _6- i ₄ aryl, C _6- ioarylCi _-4 alkyl, heteroaryl,

Ci _-5 alkoxy, H(OCH ₂ CH ₂ ) _I-6 O-, Ci _-3 alkyl(OCH ₂ CH ₂ ), _-6 O-, halo-C,. ₅ alkoxy, halo-C,. ₃ alkyl(OCH ₂ CH ₂ ) _1-6 O-, halo-CH ₂ CH ₂ O-, C ₃ . ₆ cycloalkoxy, C _3- i ₂ cycloalkylCi _-5 alkoxy, heteroarylC ₂ . ₅ alkoxy, C ₆ - ₁₄ aryloxy, C _6- ioarylCi _-4 alkoxy, heteroaryloxy, C _1-5 alkylNR ¹⁰ C(O)-, (d- ₆ alkyl) ₂ NC(O)CH(C _1-5 alkyl)-, halo- Ci- ₆ alkylNR ¹⁰ C(O)CH(Ci _-5 alkyl)-, halo-Ci- ₆ alkylOC(O)CH(Ci _-5 alkyl)-, halo- C,_ ₅ alkylNR ^l0 C(O)-, C, _-5 alkylNR ^I0 C(O)O-, C _1-5 alkylC(O)-, C,. ₅ alkylC(O)O-, C _6-10 arylC(O)- and C _6- i ₀ arylC(O)O-;

R ⁹ is hydrogen or is selected from the group consisting of halo, Ci_ ₆ alkyl, C _3-6 cycloalkyl, C ₃ _i ₂ cycloalkylCi- ₅ alkyl, C _6- i ₄ aryl, heteroaryl, halo-(CH ₂ CH ₂ ) _1-6 -; halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _1-6 -, halo-CH ₂ CH ₂ - (OCH ₂ CH ₂ )^O(CO)- and halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ), _-6 (CO)-; and each R ¹⁰ is independently H or Ci- ₆ alkyl; wherein the radiolabel comprises a radionuclide selected from the group consisting of ^{1 1} C, ¹³ N, ¹⁵ O, ¹⁸ F, ¹²³ 1, ¹²⁴ I, ¹²⁵ I, ¹³¹ I and ⁷⁷ Br; and pharmaceutically acceptable salts thereof.

7. The compound of Claim 6, wherein: For Formula I and Formula II:

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , C^alkoxy, H(OCH ₂ CH ₂ ) ,. ₆ O- and C, _-3 alkyl(OCH ₂ CH ₂ ) _1-6 O-; For Formula III: are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , C _1-5 alkoxy, H(OCH ₂ CH ₂ ) ,. ₆ O- and Ci _-3 alkyl(OCH ₂ CH ₂ ) _1-6 O-; For Formula IV:

R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , C,. ₅ alkoxy, H(OCH ₂ CH ₂ ) _I-6 O- and Ci _-3 alkyl(OCH ₂ CH ₂ ) _1-6 O-. For Formula V and Formula VI:

R ⁵ and R ⁶ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , C _1-5 alkoxy, H(OCH ₂ CH ₂ ) _1-6 O- and C _l-3 alkyl(OCH ₂ CH ₂ ), _-6 O-.

wherein the radiolabel comprises a radionuclide selected from the group consisting of ^{1 1} C, ¹³ N, ¹⁵ O, ¹⁸ F, ¹²³ 1, ¹²⁴ I, ¹²⁵ I, ¹³¹ I and ⁷⁷ Br; and pharmaceutically acceptable salts thereof.

8. The compound of any one of Claims 1 to 7, wherein the halo- moiety of the group selected from halo-C _r6 alkyl, halo-C _2-5 alkoxy, halo-C _2-3 al RyI(OCH ₂ CH ₂ ) _I-6 O-, halo-CH ₂ CH ₂ O-, halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _1-6 O-, halo-(CH ₂ CH ₂ ), _-6 -; halo-CH ₂ CH ₂ - (OCH ₂ CH ₂ )I _-6 -, halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) I _-6 O(CO)-, halo-CH ₂ CH ₂ - (OCH ₂ CH ₂ )I _-6 (CO)-, halo-C ₂ - ₆ alkylNR ¹⁰ C(O)CH(Ci _-5 alkyl)-, halo- C ₂ - ₆ alkyIOC(O)CH(C _l . ₅ alkyl)- and haloCi _-5 alkylNR ¹⁰ C(O)- is selected from the group consisting of fluoro, iodo and bromo.

9. The compound of Claim 6, wherein: For Formula I and Formula II:

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently hydrogen or are each independently selected from the group consisting of halo-C _2-5 alkoxy, haloCi-βalkyl, perhaloC,- ₆ alkyl, halo-C ₂ - ₃ alkyl(OCH ₂ CH ₂ ), _-6 O-, F-CH ₂ CH ₂ O-, F- CH ₂ CH ₂ -(OCH ₂ CH ₂ )L ₆ O-, haloC ₂ - ₆ alkylNR ¹⁰ C(O)CH(C,. ₅ alkyl)-, haloC ₂ - ₆ alkylOC(O)CH(C| _-5 alkyl)- and haIoC _2-5 alkylNR ^l0 C(O)-; For Formula III:

R , R , R and R are each independently hydrogen or are each independently selected from the group consisting of halo-Ci _-5 alkoxy, haloCi- ₆ alkyl, perhaloCi- ₆ alkyl, halo-C ₂ . ₃ alkyl(OCH ₂ CH ₂ ) _1-6 O-, F-CH ₂ CH ₂ O-, F-CH ₂ CH ₂ - (OCH ₂ CH ₂ ) _I-6 O-, haloC ₂ - ₆ alkylNR ¹⁰ C(O)CH(C _1-5 alkyl)-, haloC ₂ - ₆ alkylOC(O)CH(C, _-5 alkyl)- and haloC ₂ . ₅ alkylNR ¹⁰ C(O)-; For Formula IV:

R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or are each independently selected from the group consisting of halo-Ci^alkoxy, haloC]- ₆ alkyl, perhaloC,- ₆ alkyl, halo-C _2-3 alkyl (OCH ₂ CH ₂ ), _-6 O-, F-CH ₂ CH ₂ O-, F-CH ₂ CH ₂ - (OCH ₂ CH ₂ ) _1-6 O-, haloC ₂ - ₆ alkylNR ¹⁰ C(O)CH(C, _-5 alkyl)-, haloC ₂ - ₆ alkylOC(O)CH(Ci _-5 alkyl)- and haloC _2-5 alkylNR ¹⁰ C(O)-; For Formula V and Formula VI:

R ⁵ and R ⁶ are each independently hydrogen or are each independently selected from the group consisting of halo-Ci.salkoxy, haloCi- ₆ alkyl,

perhaloC _r6 alkyl, halo-C _2-3 alkyl(OCH ₂ CH ₂ )ι _-6 O-, F-CH ₂ CH ₂ O-, F-CH ₂ CH ₂ - (OCH ₂ CH ₂ ) , ^O-, haloC ₂ - ₆ alkylNR ' ⁰ C(O)CH(Ci _-5 alkyl)-, haloC ₂ - ₆ alkylOC(O)CH(C, _-5 alkyl)- and haloC _2-5 alkylNR ¹⁰ C(O)-; wherein the radiolabel comprises a radionuclide selected from the group consisting of ^{1 1} C, ¹³ N, ¹⁵ O, ¹⁸ F, ¹²³ 1, ¹²⁴ I, ¹²⁵ I, ¹³¹ I and ⁷⁷ Br; and pharmaceutically acceptable salts thereof.

10. The compound of Claim 6, wherein: For Formula I and Formula II:

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently hydrogen or are each independently selected from the group consisting of C ₃ _ ₆ cycloalkyl, C ₃ -i ₂ cycloalkylCi _-5 alkyl, heteroarylC _2-5 alkoxy, C ₆ _i ₄ aryl, C _6- ioarylC|. ₄ alkyl, heteroaryl, C _3-6 cycloalkoxy, C ₃ -i ₂ cycloalkylCi_ ₅ alkoxy, C ₆ .i ₄ aryloxy, heteroaryloxy, C _1-5 alkylNR ¹⁰ C(O)-, (Ci- ₆ alkyl) ₂ NC(O)CH(C,_ ₅ alkyl)-, C,. ₅ alkylNR ¹⁰ C(O)O-, d _-5 alkylC(O)-, C, _-5 alkylC(O)O-, C ₆ -i ₀ arylC(O)- and C _6-I0 arylC(O)O-; For Formula III:

R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently hydrogen or are each independently selected from the group consisting of C _3-6 cycloalkyl, C _{3-) 2} cycloalkylCi. salkyl, heteroarylC _2- salkoxy, C ₆ -i ₄ ary], C ₆ -ioarylCi _-4 alkyl, heteroaryl, C ₃ . ₆ cycloalkoxy, C _3- i ₂ cycloalkylCi. ₅ alkoxy, C ₆ -i ₄ aryloxy, C ₆ -ioarylCi_ ₄ alkoxy, heteroaryloxy, Ci. ₅ alkylNR ^I0 C(O)-, (Ci-6alkyl) ₂ NC(O)CH(Ci. ₅ alkyl)-, C,. ₅ alkylNR ¹⁰ C(O)O-, Ci_ ₅ alkylC(O)-, C,. ₅ alkylC(O)O-, C _6-10 arylC(O)- and C ₆ . ₁₀ arylC(O)O-; For Formula IV:

R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or are each independently selected from the group consisting of Ci_ ₆ alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi. ₅ alkyl, heteroarylC _2-5 alkoxy, C _6- i ₄ aryl, C ₆ .ioarylCi _-4 alkyl, heteroaryl, C ₃ . ₆ cycloalkoxy, heteroaryloxy, C _1-5 alkylNR ¹⁰ C(O)-, (Cr ₆ alkyl) ₂ NC(O)CH(Ci. ₅ alkyl)-, C,. ₅ alkylNR ¹⁰ C(O)O-, C,. ₅ alkylC(O)-, Ci _-5 alkylC(O)O-, C _6-I0 arylC(O)- and C _6- ioarylC(0)0-; For Formula V and Formula VI:

R ⁵ and R ⁶ are each independently hydrogen or are each independently selected from the group consisting of Ci _-6 alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylC|. ₅ alkyl, heteroarylC _2-5 alkoxy, C ₆ -i ₄ aryl, C ₆ -ioarylCi _-4 alkyl, heteroaryl, C _3-6 cycloalkoxy, C _3- i ₂ cycloalkylCi. ₅ alkoxy, C ₆ .i ₄ aryloxy, C ₆ -ioarylCi _-4 alkoxy, heteroaryloxy, C,. ₅ alkylNR ^l0 C(O)-, (C,- ₆ alkyl) ₂ NC(O)CH(C _I-5 alkyl)-, C, _-5 alkylNR ¹⁰ C(O)O-, Cι _-5 alkylC(O)-, Ci _-5 alkylC(O)O-, C ₆ -i ₀ arylC(O)- and C _6-10 arylC(O)O-; wherein the radiolabel comprises a radionuclide selected from the group consisting of ^{1 1} C, ¹³ N, ¹⁵ O, ¹⁸ F, ¹²³ 1, ¹²⁴ I, ¹²⁵ I, ¹³¹ I and ⁷⁷ Br; and pharmaceutically acceptable salts thereof.

1 1. The compound of Claim 6, wherein: For Formula I and Formula II:

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently hydrogen or selected from the group consisting of F-Ci- ₆ alkyl, F-Ci _-5 alkoxy, F-Ci _-3 alkyl(OCH ₂ CH ₂ ),. ₆ O-, F-CH ₂ CH ₂ O-, F-CH ₂ CH ₂ -(OCH ₂ CH ₂ ), _-6 O-, 4-(F-C,- ₆ alkyl)-lH-l ,2,3-triazol-l-yl- (C _2-5 alkoxy), F-C ₂ - ₆ alkylNR ¹⁰ C(O)CH(Ci- ₅ alkyl)-, F-Ci- ₆ alkylOC(O)CH(Ci _-5 alkyl)- and F-Ci _-5 alkylNR ¹⁰ C(O)-; For Formula III:

R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently hydrogen or selected from the group consisting of F-Ci- ₆ alkyl, F-d-salkoxy, F-C i _-3 alkyl(OCH ₂ CH ₂ ) _I-6 O-, F- CH ₂ CH ₂ O-, F-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _1-6 O-, 4-(F-C _r6 alkyl)-l H-1 , 2,3-triazol-l-yl- (C _2-5 alkoxy), F-C ₂ - ₆ alkylNR ¹⁰ C(O)CH(C, _-5 alkyl)-, F-C _l - ₆ alkylOC(O)CH(C _l-5 alkyl)- and F-C, _-5 alkylNR ¹⁰ C(O)-;

For Formula IV:

R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or selected from the group consisting of F-Ci- ₆ alkyl, F-Q.salkoxy, F-C i _-3 alkyl (OCH ₂ CH ₂ ) _I-6 O-, F- CH ₂ CH ₂ O-, F-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _L6 O-, 4-(F-C _r6 alkyl)-l H-1 , 2,3-triazol-l-yl- (C _2-5 alkoxy), F-C i - ₆ alkylNR ¹⁰ C(O)CH(Ci _-5 alkyl)-, F-C , - ₆ alkylOC(O)CH(C , _-5 alkyl)- and F-Ci _-5 alkylNR ¹⁰ C(O)-;

For Formula V and Formula VI:

R ⁵ and R are each independently hydrogen or selected from the group consisting of F-Ci- ₆ alkyl, F-Ci. ₅ alkoxy, F-C _1-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, F-CH ₂ CH ₂ O-, F-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _L6 O-, 4-(F-Q - ₆ alkyl)- IH-1 ,2,3-triazol-l-yl-(C _2-5 alkoxy), F-

Cr ₆ a]kylNR ¹⁰ C(O)CH(C,. ₅ alkyl)-, F-C,- ₆ alkylOC(O)CH(C,. ₅ alkyl)- and F-C ₁ . 5alkylNR ¹⁰ C(O)-; wherein the radiolabel comprises a radionuclide selected from the group consisting of ^{1 1} C, ¹³ N, ¹⁵ O, ¹⁸ F, ¹²³ 1, ¹²⁴ I, ¹²⁵ I, ¹³¹ I and ⁷⁷ Br; and pharmaceutically acceptable salts thereof.

12. The compound of Claim 6, wherein: For Formula I and Formula II: at least four of R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are hydrogens; For Formula III: at least two of R ⁵ , R ⁶ , R ⁷ and R ⁸ are hydrogens; For Formula IV: at least two of R ¹ , R ² , R ³ and R ⁴ are hydrogens; For Formula V and Formula VI: at least one of R ⁵ or R ⁶ is a hydrogen; wherein the radiolabel comprises a radionuclide selected from the group consisting of ^{1 1} C, ¹³ N, ¹⁵ O, ¹⁸ F, ¹²³ 1, ¹²⁴ I, ¹²⁵ I, ¹³¹ I and ⁷⁷ Br; and pharmaceutically acceptable salts thereof.

13. The compound of any one of Claims 1 to 12, wherein the amino group is selected from the group consisting Of NH ₂ -, CH ₃ NH-, (CH ₃ ) ₂ N-, Ci _-3 -alkylNH-, F- C _2-3 -alkylNH-, F-(C _2-3 -alkylO) _I-4 -alkyl-NH-, (C _l-3 -alkyl) ₂ N-, C,. ₆ alkylNH-, (Ci _-6 alkyl) ₂ N-, C _3-6 cycloalkylNH-, (C _3-6 cycloalkyl) ₂ N-, C _3- i ₂ cycloalkylCi _-5 alkylNH-, C _6- i ₄ arylNH-, heteroarylNH-, C ₆ -i ₄ aryloxyNH-, and heteroaryloxyNH-.

14. The compound of any one of Claims 1 to 13 of the Formula I, II, V and VI, wherein X is a bond and R ⁹ is hydrogen.

15. The compound of any one of Claims 1-14, wherein the compound comprises at lleeaasstt oonnee rraaddiioonnuclide selected from the group consisting of ¹¹ C, ¹⁵ O, ¹⁸ F, ¹²³ I I, ¹³¹ I and ⁷⁷ Br.

16. The radiolabeled compound of Claim 1 that is: 2-(2-fluoroethoxy)-9H-carbazole;

9-(2-fluoroethyl)-9H-carbazol-2-ol;

N-(2-fluoroethyl)-7-(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-9H-carbazol-3-amine;

7-(2-fluoroethoxy)-N,N-dimethyl-9H-carbazol-2-amine;

7-(2-(2-(2-fluoroethoxy)ethoxy)ethoxy)-N-methyl-9H-carbazol-3-amine; l -(3,6-diamino-9H-carbazol-9-yl)-3-(2-(2-(2-fluoroethoxy)ethoxy)ethoxy)propan-l- one;

N-(2-fluoroethyl)-2-hydroxy- 1 1 H-benzo[a]carbazole-3-carboxamide;

2-(6-chloro-9H-carbazol-2-yl)-N-(2-fluoroethyl)propanamide;

2-(6-fluoro-9H-carbazol-2-yl)-N,N-dimethylpropanamide;

2-methoxy-9H-carbazole;

6-iodo-2-methoxy-9H-carbazole;

2-(2-fluoroethoxy)-9H-carbazole;

9-(2-fluoroethyl)-9H-carbazol-2-ol;

N-(2-fluoroethyl)-7-(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-9H-carbazol-3-amine;

7-(2-fluoroethoxy)-N,N-dimethyl-9H-carbazol-2-amine;

7-(2-(2-(2-fluoroethoxy)ethoxy)ethoxy)-N-methyl-9H-carbazol-3-amine; l-(3,6-diamino-9H-carbazol-9-yl)-3-(2-(2-(2-fluoroethoxy)ethoxy)ethoxy)propan-l- one;

N-(2-fluoroethyl)-2-hydroxy-l 1 H-benzo[a]carbazole-3-carboxamide;

2-(6-chloro-9H-carbazol-2-yl)-N-(2-fluoroethyl)propanamide; and

2-(6-fluoro-9H-carbazol-2-yl)-N,N-dimethylpropanamide.

17. A radiolabeled compound of the formula Ha:

wherein:

X is a bond or is selected from the group consisting of Ci_ ₆ alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ^I0 )C(S)-, -S(O)N(R ¹⁰ )- and - N(R'°)S(O) ₂ ;

R ² , R ³ , R ⁴ , R ⁶ , R ⁷ and R ⁸ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-C _r6 alkyl, perhaloC,- ₆ alkyl, C,. ₆ alkyl, C _3-6 cycloalkyl, C ₃ .i ₂ cycloalkylCi_ ₅ alkyl, C ₆ -i ₄ aryl, C _6- i ₀ arylCi _-4 alkyl, heteroaryl, C|. ₅ alkoxy, H(OCH ₂ CH ₂ ),. ₆ O-, Ci _-3 alkyl(OCH ₂ CH ₂ ) _{1 -6} O-, halo-Ci. ₅ alkoxy, halo-Ci _-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ )i _-6 O-, C _3-6 cycloalkoxy, C _3- i ₂ cycloalkylCi_ ₅ alkoxy, heteroarylC _2-5 alkoxy, C ₆ _i ₄ aryloxy, C _6- ioarylCi- ₄ alkoxy, heteroaryloxy, C, _-5 alky INR ¹⁰ C(O)-, (C _r6 alkyl) ₂ NC(O)CH(C ₁ . ₅ alkyl)-, halo- Ci- ₆ alkylNR ¹⁰ C(O)CH(C] _-5 alkyl)-, halo-Cr6alkylOC(O)CH(C, _-5 alkyl)-, halo- Ci _-5 alkylNR ¹⁰ C(O)-, C,. ₅ alkylNR ¹⁰ C(O)O-, C _1-5 alkylC(O)-, C,- ₅ alkylC(O)O-, C _6- i ₀ arylC(O)- and C ₆ -i ₀ arylC(O)O-; provided that at least any two of R ² , R ³ , R ⁴ , R ⁶ , R ⁷ and R ⁸ are hydrogens, and at least one of R ² , R ³ , R ⁴ , R ⁶ , R ⁷ , R ⁸ and R ⁹ comprises the radiolabel;

R ⁹ is hydrogen or is selected from the group consisting of halo, Ci _-6 alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi. ₅ alkyl, C _ό -uaryl, C ₆ -ioarylCi _-4 alkyl, heteroaryl, halo-(CH ₂ CH ₂ ), _-6 -; halo-CH ₂ CH ₂ - (OCH ₂ CH ₂ )I _-6 O(CO)- and halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ )i. ₆ (CO)-; each R ¹⁰ is independently H or Ci- ₆ alkyl; wherein the radiolabel comprises a radionuclide selected from the group consisting of ¹¹ C, ¹³ N, ¹⁵ O, ¹⁸ F, ¹²³ 1, ¹²⁴ I, ¹²⁵ I, ¹³¹ I and ⁷⁷ Br; and pharmaceutically acceptable salts thereof.

18. The compound of Claim 17, wherein:

X is a bond or is selected from the group consisting of Ci_ ₆ alkylenyl, -C(O)-, -C(O)O- and -N(R ¹⁰ )C(O)-;

R ² , R ³ , R ⁴ , R , R ⁷ and R ⁸ are each independently hydrogen or are each independently selected from the group consisting of Ci _-3 alkylNH-, halo, cyano, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , halo-C,- ₆ alkyl, perhaloCi- ₆ alkyl, C _1-6 alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi _-5 alkyl, C ₆ -i ₄ aryl, C ₆ -ioarylCi _-4 alkyl, heteroaryl, Ci _-5 alkoxy, H(OCH ₂ CH ₂ ) _1-6 O-, C i. ₃ alkyl (OCH ₂ CH ₂ ) _I-6 O-, halo-Ci. ₅ alkoxy, halo-Ci _-3 alkyl(OCH ₂ CH ₂ ), _-6 O-, halo-CH ₂ CH ₂ O-, C ₃ . ₆ cycloalkoxy, C _3- ι ₂ cycloalkylCi. ₅ alkoxy, C _6- i ₄ aryloxy, C _6- ioarylCi _-4 alkoxy, heteroaryloxy, heteroarylC _2-5 alkoxy, C,. ₅ alkylNR ¹⁰ C(O)-, (Ci- ₆ alkyl) ₂ NC(O)CH(Ci _-5 alkyl)-, halo- C , - ₆ alkylNR' ⁰ C(O)CH(C i _-5 alkyl)-, halo-C , - ₆ alkyl0C(0)CH(C , _-5 alkyl)-, halo-

C,. ₅ alkylNR ¹⁰ C(O)-, C _1-5 alkylNR ¹⁰ C(O)O-, C _1-5 a]kylC(O)-, C, _-5 alkylC(O)O-, C _6- i ₀ arylC(O)- and C _6- , _o ary IC(O)O-; and

R ⁹ is hydrogen or is selected from the group consisting of halo, Cι- ₆ alkyl, C _3-6 cycloalkyl, Ca.^cycloalkylCi.salkyl, C _6- | ₄ aryl, C ₆ -ioarylCi _-4 alkyl, heteroaryl, halo-(CH ₂ CH ₂ ),, ₆ -; halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ )i _-6 -, halo-CH ₂ CH ₂ - (OCH ₂ CH ₂ ) _I-6 O(CO)- and halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ), _-6 (CO)-.

19. The compound of Claim 17, wherein:

X is a bond or is selected from the group consisting of -C(O)-, -C(O)O- and -N(R ¹⁰ )C(O)-;

R ² , R ⁴ , R ⁶ and R ⁸ are each hydrogen;

R ³ and R ⁷ are each independently selected from the group consisting of Ci _-3 alkylNH-, (Ci _-3 alkyl) ₂ N-, (halo-Ci- ₆ alkyl)N(C _)-3 alkyl)-, halo-CH ₂ CH ₂ - (OCH ₂ CH ₂ ) _1-6 N(Ci_ ₃ alkyl)-, halo, hydroxyl, halo-Ci- ₆ alkyl, C _6-10 arylC _1-4 alkyl, 4- (halo-C i - ₆ alkyl)-triazol- 1 -yl)C _2-5 alkoxy, C i _-5 alkoxy, H(OCH ₂ CH ₂ ) _I-6 O-, halo-C| _-5 alkoxy, halo-Ci _-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo- CH ₂ CH ₂ O-, halo-C,- ₆ alkylNR ^l0 C(O)CH(C,. ₅ alkyl)-, halo-Ci- ₆ alkylOC(O)CH(Ci. ₅ alkyl)-, halo-C _1-5 alkylNR ¹⁰ C(O)-, Ci_ ₅ alkylC(O)-; and

R ⁹ is hydrogen or is selected from the group consisting of halo, C ₃ -i ₂ cycloalkylCi_ ₅ alkyl, C ₆ -i ₄ aryl, heteroaryl, halo-(CH ₂ CH ₂ )i_ ₆ -; halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ),. ₆ -, halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _{1 6} O(CO)- and halo- CH ₂ CH ₂ -(OCH ₂ CH ₂ )^(CO)-.

20. A radiolabeled compound of the formula III:

wherein:

Y and Y' are each independently a bond or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , C(S)NH ₂ , haloC _r6 alkyl, perhaloC _r6 alkyl, C| _-6 alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi- ₅ alkyl, C _6- | ₄ aryl, Co-ioarylCi^alkyl, heteroaryl, Ci _-5 alkoxy,

H(OCH ₂ CH ₂ ) _I-6 O-, Ci _-3 alkyl(OCH ₂ CH ₂ )i- ₆ θ-, halo-C _1-5 alkoxy, halo-Ci _-3 alkyl(OCH ₂ CH ₂ ) _1-6 O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C ₃ -i ₂ cycloalkylCi- ₅ alkoxy, heteroarylC ₂ _ ₅ alkoxy, C _6- | ₄ aryloxy, C _6- ioarylCi- ₄ alkoxy and heteroaryloxy when R ^{1 1} and R ¹² are absent;

R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-Ci- ₆ alkyl, perhaloC,- ₆ alkyI, C, _-6 alkyl, C ₃ . ₆ cycloalkyl, C ₃ -i ₂ cycloalkylCi _-5 alkyl, C _6- i ₄ aryl, C _6- ioarylCi- ₄ alkyl, heteroaryl, C _1-5 alkoxy, H(OCH ₂ CH ₂ ) _I-6 O-, Ci. ₃ alkyl(OCH ₂ CH ₂ ), _-6 O-, halo-C, _-5 alkoxy, halo-C| _-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C3-i ₂ cycloalkylCi- ₅ alkoxy, heteroarylC ₂ . ₅ alkoxy, C _6- i ₄ aryloxy, C ₆ _ioarylCi _-4 alkoxy, heteroaryloxy, Ci _-5 alkylNR ¹⁰ C(O)-, (C,- ₆ alkyl) ₂ NC(O)CH(C _1-5 alkyl)-, halo- C , - ₆ alkylNR ^!0 C(O)CH(C , _-5 alkyl)-, halo-C i - ₆ alkyl OC(O)CH(C i _-5 alkyl)-, halo- C,. ₅ alkylNR ^I0 C(O)-, Ci _-5 alkylNR ¹⁰ C(O)O-, C,. ₅ alkylC(O)-, Ci _-5 alkylC(O)O-, C _6- i ₀ arylC(O)- and C _6- i ₀ arylC(O)O-; or at least one of R ⁵ and R ⁶ , R ⁶ and R ⁷ or R ⁷ and R together with the carbon atoms to which they are attached to, form a substituted or unsubstituted aromatic or non-aromatic carbocyclic or heterocyclic ring; provided that at least one of R ⁵ , R ⁶ , R ⁷ and R ⁸ is a hydrogen; each R ¹⁰ is independently H or C|- ₆ alkyl;

R ^{1 1} and R ¹² are each independently absent, a hydrogen or are each independently selected from the group consisting of halo, Ci _-6 alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi- ₅ alkyl, C _6- i ₄ aryl, C _6- ioarylCi _-4 alkyl, heteroaryl, halo-(CH ₂ CH ₂ )i _-6 -, halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ )i _-6 -, 1IaIo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _I-6 O(CO)- and halo- CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _J-6 (CO)-; provided that at least one of R ⁵ to R ¹² comprises a radiolabel; wherein the radiolabel comprises a radionuclide selected from the group consisting of ¹¹ C, ¹³ N, ¹⁵ O, ¹⁸ F, ¹²³ 1, ¹²⁴ 1, ¹²⁵ I, ¹³¹ I and ⁷⁷ Br; and pharmaceutically acceptable salts thereof.

21. The compound of Claim 20, wherein:

Y and Y' are each independently selected from the group consisting of amino, halo, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-C, - ₆ alkyl, perhaloC _r6 alkyl, Ci _-6 alkyl, Ci _-5 alkoxy, H(OCH ₂ CH ₂ ) _{I -6} O-,

C,. ₃ alkyl(OCH ₂ CH ₂ ),. ₆ O-, halo-C, _-5 alkoxy, halo-C|. ₃ alkyl(OCH ₂ CH ₂ ),. ₆ O- and halo-CH ₂ CH ₂ O- when R ¹¹ and R ¹² are absent; and

R ⁵ , R ⁶ , R ⁷ and R are each independently hydrogen or are each independently selected from the group consisting of amino, halo, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , haloC]- ₆ alkyl, perhaloCi- ₆ alkyl, C,. ₆ alkyl, C _3-6 cycloalkyl, C _6- ioarylCi _-4 alkyl, heteroaryl, C,. ₅ alkoxy, H(OCH ₂ CH ₂ ), _-6 O-, C , _-3 alkyl (OCH ₂ CH ₂ ),. ₆ O-, halo- C _2-5 alkoxy, halo-C _2-3 alkyl(OCH ₂ CH ₂ ), _-6 O-, halo-CH ₂ CH ₂ O-, C ₃ . ₆ cycloalkoxy, C,. ₅ alkylNR ¹⁰ C(O)-, (C,- ₆ alkyl) ₂ NC(0)CH(Ci. ₅ alkyl)-, halo-C ₂ - ₆ alkylNR ¹⁰ C(0)CH(C,. ₅ alkyl>, halo-Ci- ₆ alkylOC(O)CH(C,. ₅ alkyl)- and halo-C, _-5 alkylNR ¹⁰ C(O)-.

22. The compound of Claim 20, wherein:

Y and Y' are each independently a bond or are each independently selected from the group consisting of amino, halo, hydroxyl, -C(O)NH ₂ , haloC,- ₆ alkyl, perhaloC,- ₆ alkyl, Ci _-6 alkyl, C ₃ . ₆ cycloalkyl, C ₃ _, ₂ cycloalkylC,. ₅ alkyl, C ₆ -i ₄ aryl, C ₆ .i ₀ arylC, _-4 alkyl, heteroaryl, C _1-5 alkoxy, H(OCH ₂ CH ₂ ) ,. ₆ O-, C,. ₃ alkyl(OCH ₂ CH ₂ )i. ₆ O-, halo-C,. ₅ alkoxy, halo-C,. ₃ alkyl(OCH ₂ CH ₂ ),. ₆ O- and halo-CH ₂ CH ₂ O- when R ¹ ' and R ¹² are absent; and

R , R , R and R are each independently hydrogen or are each independently selected from the group consisting of halo-Ci.salkoxy, halo-C, _-3 alkyl(OCH ₂ CH ₂ ),. ₆ O-, halo-CH ₂ CH ₂ O-, FCH ₂ CH ₂ -(OCH ₂ CH ₂ )L ₆ O-, haloC,- ₆ alkylNR ¹⁰ C(O)CH(C,. ₅ alkyl)-, halo-C,- ₆ alkylOC(O)CH(C, _-5 alkyl)- and halo-C,. ₅ alkylNR ¹⁰ C(O)-.

23. The compound of Claim 20, wherein:

Y and Y' are each independently a bond or are each independently selected from the group consisting of amino, halo, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , haloC,- ₆ alkyl, perhaloC,- ₆ alkyl, C, _-5 alkoxy, H(OCH ₂ CH ₂ ) , _-6 O-, C,. ₃ alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-C _2-5 alkoxy, halo-C,. ₃ alkyl(OCH ₂ CH ₂ )i. ₆ O-, halo- CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C _3- , ₂ cycloalkylC,. ₅ alkoxy, heteroarylC ₂ - ₅ alkoxy, C ₆ ., ₄ aryloxy, C ₆ -ioarylC,. ₄ alkoxy and heteroaryloxy when R ¹¹ and R ¹² are absent; and

R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently hydrogen or are each independently selected from the group consisting of C ₃ . ₆ cycloalkoxy, heteroarylC _2-5 alkoxy, C _6- , ₄ aryloxy, C _6- ,oarylC, _-4 alkoxy, heteroaryloxy, C,.

₅ alky]NR ¹⁰ C(O)-, (C,- ₆ alkyl) ₂ NC(O)CH(C _1-5 alkyl)-, C,. ₅ alkylC(O)-, C _1-5 alkylC(O)O-, C _6- , ₀ arylC(O)- and C ₆ -i ₀ arylC(O)O-.

24. A radiolabeled compound of the formula IV:

wherein:

W is O oi -N-X-R ⁹

X is a bond or is selected from the group consisting of Ci _-6 alkylenyl, -C(O)-,

-C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ¹⁰ )C(S)-, -S(O)N(R ¹⁰ )- and -

N(R ^I0 )S(O) ₂ -;

Y and Y' are each independently a bond or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , - C(S)NH ₂ , halo-Ci- ₆ alkyl, perhaloCi- ₆ alkyl, C _)-6 alkyl, C _3-6 cycloalkyl, C ₃ _i ₂ cycloalkylCi. ₅ alkyl, C ₆ -i ₄ aryl, heteroaryl, Ci _-5 alkoxy, H(OCH ₂ CH ₂ )I _-6 O-, Ci. ₃ alkyl(OCH ₂ CH ₂ ),. ₆ O-, halo-Ci _-5 alkoxy, halo-C| _-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, heteroarylC _2-5 alkoxy, C _6- i ₄ aryloxy, C ₆ -ioarylCi _-4 alkoxy and heteroaryloxy when R ¹¹ and R ¹² are absent; or Y is

and R ¹² is absent;

R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-C,- ₆ alkyl, perhaloC _r6 alkyl, C, _-6 alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi. ₅ alkyl, C _6- i ₄ aryl, heteroaryl, Ci.salkoxy, H(OCH ₂ CH ₂ ) _1-6 O-, Ci _-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-Ci _-5 alkoxy, halo-Ci _-3 alkyl(OCH ₂ CH ₂ ) _1-6 O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C _3- ] ₂ cycloalkylCi. ₅ alkoxy, heteroarylC _2-5 alkoxy, C _6- i ₄ aryloxy, heteroaryloxy, C,. ₅ alkylNR ¹⁰ C(O)-, (C,- ₆ alkyl) ₂ NC(O)CH(C, _-5 alkyl)-, halo-

CrealkylNR^CCOJCHCd-salkyO-. halo-Ci-ealkylOCCO^HCCi.salkyO-. halo- C _1-5 alkylNR ^l0 C(O)-, C _1-5 alkylNR ¹⁰ C(O)O-, C,. ₅ alkylC(O)-, C, _-5 alkylC(O)O-, C ₆ .ioarylC(0)- and C _6- i ₀ arylC(O)O-; or at least one of R ⁵ and R ⁶ , R ⁶ and R ⁷ or R ⁷ and R ⁸ together with the carbon atoms to which they are attached to, form a substituted or unsubstituted aromatic or non-aromatic carbocyclic or heterocyclic ring; provided that at least one of R ¹ , R ² , R ³ and R ⁴ is a hydrogen;

R ⁵ , R ⁶ , R ⁷ , R ⁸ and R ⁰ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-C,- ₆ alkyl, perhaloCi- ₆ alkyl, Ci _-6 alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi_ ₅ alkyl, C _6- i ₄ aryl, heteroaryl, Ci _-5 alkoxy, H(OCH ₂ CH ₂ ) _1-6 O-, Ci- ₃ alkyl(OCH ₂ CH ₂ ) _! . ₆ O-, halo-Ci _-5 alkoxy, halo-Ci. ₃ alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-CH ₂ CH ₂ O-, C ₃ . ₆ cycloalkoxy, C _3- i ₂ cycloalkylCi. ₅ alkoxy, heteroarylC _2-5 alkoxy, C ₆ -i ₄ aryloxy, C ₆ .ioarylCi _-4 alkoxy, heteroaryloxy, Ci _-5 alkylNR ^l0 C(O)-, (Ci- ₆ alkyl) ₂ NC(O)CH(Ci_ ₅ alkyl)-, halo- Ci- ₆ alkylNR ¹⁰ C(O)CH(Ci. ₅ alkyl)-, halo-Ci-6alkylOC(O)CH(Ci. ₅ alkyl)-, halo- C, _-5 alkylNR ¹⁰ C(O)-, Ci.5alkylNR ¹⁰ C(O)O-, C, _-5 alkylC(O)-, Ci. ₅ alkylC(O)O-, C _6-10 arylC(O)- and C _6- i ₀ arylC(O)O-;

R ⁹ is hydrogen or is selected from the group consisting of halo, Ci _-6 alkyl, C ₃ . ₆ cycloalkyl, C ₃ .i ₂ cycloalkylCi_ ₅ alkyl, C _6- i ₄ aryl, heteroaryl, halo-(CH ₂ CH ₂ )i _-6 -; halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _1-6 -, halo-CH ₂ CH ₂ - (OCH ₂ CH ₂ ) _I-6 O(CO)- and halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _1-6 (CO)-; each R ¹⁰ is independently H or Cj- ₆ alkyl; and

R ¹¹ and R ¹² are each independently absent, a hydrogen or are each independently selected from the group consisting of halo, Ci _-6 alkyl, Cs- _ό Cycloalkyl, C _3- i ₂ cycloalkylCi. ₅ alkyl, C ₆ -i ₄ aryl, C _ό -ioarylCi^alkyl, heteroaryl, halo-(CH ₂ CH ₂ )i_6-; halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _1-6 -, halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _I-6 O(CO)- and halo- CH ₂ CH ₂ -(OCH ₂ CH ₂ ) , - ₆ (CO)-; provided that at least one of R ¹ to R ¹² comprises a radiolabel, as defined herein; wherein the radiolabel comprises a radionuclide selected from the group ng of ¹¹ C, ¹³ N, ¹⁵ O, ¹⁸ F, ¹²³ 1, ¹²⁴ I, ¹²⁵ I, ¹³¹ I and ⁷⁷ Br; and pharmaceutically acceptable salts thereof.

25. The compound of Claim 24, wherein: W is O or -N-X-R ⁹ ;

X is a bond or is selected from the group consisting of Ci _-6 alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ^I0 )C(O)-; and

R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR , -C(O)NH ₂ , -C(S)NH ₂ , halo-C,- ₆ alkyl, perhaloC,- ₆ alkyl, C _1-6 alkyl, C _3-6 cycloalkyl, Q-ncycloalkylCi.salkyl, Q-uaryl, C ₆ -ioarylCi _-4 alkyl, heteroaryl, C _1-5 alkoxy, H(OCH ₂ CH ₂ ) _1-6 O-, C, _-3 alkyl(OCH ₂ CH ₂ ) _1-6 O-, halo-C,. ₅ alkoxy, halo-C,. ₃ alkyl(OCH ₂ CH ₂ ), _-6 O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C _3- i ₂ cycloalkylC|_ ₅ alkoxy, heteroarylC _2-5 alkoxy, C _ό -^aryloxy, Cβ-ioarylC _M alkoxy, C _1-5 alkylC(O)-, C _1-5 alkylC(O)O-, C _6- i ₀ arylC(O)- and C _6-10 arylC(O)O-.

26. The compound of Claim 24, wherein: W is O or -N-X-R ⁹ ;

X is a bond or is selected from the group consisting of Ci _-6 alkylenyl, -C(O)-, -C(O)O- and -N(R ¹⁰ )C(O)-;

Y and Y' are each independently a bond or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , - C(S)NH ₂ , halo-C,- ₆ alkyl, perhaloCi- ₆ alkyl, d_ ₅ alkoxy, H(OCH ₂ CH ₂ ) _I-6 O-, C, _-3 alkyl(OCH ₂ CH ₂ )i_ ₆ O-, halo-Ci_ ₅ alkoxy, halo-C,. ₃ alkyl(OCH ₂ CH ₂ ) _I-6 O-, halo- CH ₂ CH ₂ O-, C _6- i ₄ aryloxy, C _6- ioarylCi _-4 alkoxy and heteroaryloxy when R ¹¹ and R ¹² are absent; and

R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, hydroxyl, halo-Ci- ₆ alkyl, perhaloCi- ₆ alkyl, Ci- ₆ alkyl, C _3-6 cycloalkyl, C ₃ .i ₂ cycloalkylCi _-5 alkyl, heteroarylC ₂ . ₅ alkoxy, Ci _-5 alkoxy, H(OCH ₂ CH ₂ ) , _-6 O- and Ci. ₃ alkyl(OCH ₂ CH ₂ )i _-6 O-.

27. The compound of Claim 24, wherein: W is O;

Y and Y' are each independently a bond or are each independently selected from the group consisting of amino, halo, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , halo- C ₂ - ₆ alkyl, perhaloCi- ₆ alkyl, Ci _-6 alkyl, C _3-6 cycloalkyl, C ₃ .i ₂ cycloalkylCi. ₅ alkyl, C _6-14 aryl, C _6- i ₀ arylCi _-4 alkyl, heteroaryl, Ci _-5 alkoxy, H(OCH ₂ CH ₂ ) , _-6 O-,

C,. ₃ alkyl(OCH ₂ CH ₂ ) _1-6 O-, halo-Ci _-5 alkoxy, halo-C,. ₃ alkyl(OCH ₂ CH ₂ )i _-6 O-, halo- CH ₂ CH ₂ O-, C ₃ . ₆ cycloalkoxy, C _3- i ₂ cycloalkylCi _-5 alkoxy, heteroarylC ₂ _5alkoxy, C _6- i4aryloxy, C _6- ioarylCi. ₄ alkoxy and heteroaryloxy when R ^{1 1} and R ¹² are absent; and

R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or are each independently selected from the group consisting of halo-Ci.salkoxy, halo-CH2CH2θ-, halo-Ci-6alkylNR ^I0 C(O)CH(Ci. ₅ alkyl)-, halo-C _r6 alkylOC(O)CH(Ci _-5 alkyl)- and halo-Ci _-5 alkylNR ¹⁰ C(O)-.

28. The compound of Claim 24, wherein:

W is O;

X is a bond or is selected from the group consisting of Ci _-6 alkylenyl, -C(O)-, -C(O)O-;

Y and Y' are each independently a bond or are each independently selected from the group consisting of amino, halo, hydroxyl, -C(O)NH ₂ , -C(S)NH ₂ , halo- Ci- ₆ alkyl, perhaloCi- ₆ alkyl, Ci-βalkyl, C _3-6 cycloalkyl, Q.^cycloalkylQ-salkyl, C _6- i ₄ aryl, C _6- i ₀ arylCi_ ₄ alkyl, heteroaryl, d _-5 alkoxy, H(OCH ₂ CH ₂ ) _I-6 O-, Ci _-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-C,. ₅ alkoxy, halo-C _1-3 alkyl(OCH ₂ CH ₂ )i _-6 O- and halo-CH ₂ CH ₂ O- when R ¹¹ and R ¹² are absent; and

R ¹ , R ² , R ³ and R ⁴ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , - C(S)NH ₂ , halo-d-ealkyl, perhaloCi- ₆ alkyl, C _1-6 alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi _-5 alkyl, C _6- i ₄ aryl, C ₆ -ioarylCi _-4 alkyl, heteroaryl, Ci_salkoxy, H(OCH ₂ CH ₂ ) _1-6 O-, Ci _-3 alkyl(OCH ₂ CH ₂ ), _-6 O-, halo-C,. ₅ alkoxy, halo-Ci _-3 alkyl(OCH ₂ CH ₂ ) _{I -6} O- and halo-CH ₂ CH ₂ O-; or at least one of R ¹ and R ² , R ² and R ³ or R ³ and R ⁴ together with the carbon atoms to which they are attached to, form a substituted or unsubstituted aromatic or non-aromatic carbocyclic or heterocyclic ring; provided that at least any two of R ¹ , R ² , R ³ and R ⁴ are hydrogens;

R is hydrogen or is selected from the group consisting of halo, Ci _-6 alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi. ₅ alkyl, C ₆ -i ₄ aryl, C ₆ -ioarylC| _-4 alkyl, heteroaryl, halo-(CH ₂ CH ₂ ) _1-6 -; halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ )^-, halo-CH ₂ CH ₂ - (OCH ₂ CH ₂ ), ^0(CO)- and halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ )i _-6 (CO)-; and each R ¹⁰ is independently H or Ci- ₆ alkyl.

29. A radiolabel compound of the formula VI:

wherein:

X is a bond or is selected from the group consisting of Ci_ ₆ alkylenyl, -C(O)-, -C(S)-, -C(O)O-, -C(S)O-, -N(R ¹⁰ )C(O)-, -N(R ¹⁰ )C(S)-, -S(O)N(R ¹⁰ )- and - N(R ¹⁰ )S(O) ₂ -;

Y is a bond or is selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-C _r6 alkyl, perhaloC,- ₆ alkyl, Ci _-6 alkyl, C _3-6 cycloalkyl, C ₃ .| ₂ cycloalkylCi _-5 alkyl, C ₆ -i ₄ aryl, C _6- ioarylCi _-4 a]kyl, heteroaryl, Ci _-5 alkoxy, H(OCH ₂ CH ₂ ) _I-6 O-, Ci _-3 alkyl(OCH ₂ CH ₂ ) _)-6 O-, halo- C, _-5 alkoxy, halo-C, _-3 alkyl(OCH ₂ CH ₂ ) _1-6 O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C _3- i ₂ cycloalkylCi _-5 alkoxy, heteroarylC _2-5 alkoxy, C _6- i ₄ aryloxy, C _6- ioarylCi-4alkoxy and heteroaryloxy;

R ⁵ and R ⁶ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, cyano, nitro, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , haloCi-ealkyl, perhaloC _r6 alkyl, C, _-6 alkyl, C _3-6 cycloalkyl, C ₃ _i ₂ cycloalkylC|. ₅ alkyl, C ₆ _i ₄ aryl, heteroaryl, Ci.salkoxy, H(OCH ₂ CH ₂ ) _1-6 O-, C _1-3 alkyl(OCH ₂ CH ₂ ) ₁ . ₆ O-, halo-Ci _-5 alkoxy, halo-Ci. ₃ alkyl(OCH ₂ CH ₂ ),. ₆ O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C ₃ .i ₂ cycloalkylCi. ₅ alkoxy, heteroarylC _2-5 alkoxy, C _6-14 aryloxy, heteroaryloxy, Ci _-5 alkylNR ¹⁰ C(O)-, (Ci- ₆ alkyl) ₂ NC(O)CH(C, _-5 alkyl)-, halo- Ci- ₆ alkylNR ^l0 C(O)CH(Ci. ₅ alkyl)-, halo-C,- ₆ alkylOC(O)CH(C _1-5 alkyl)-, halo- C _1-5 alkylNR ¹⁰ C(O)-, Ci _-5 alkylNR ¹⁰ C(O)O-, C, _-5 alkylC(O)-, C,. ₅ alkylC(O)O-, C _6- i ₀ arylC(O)- and C _6- i ₀ arylC(O)O-; or R ⁵ and R ⁶ together with the carbon atoms to which they are attached to, form a substituted or unsubstituted aromatic or non- aromatic carbocyclic or heterocyclic ring;

R ⁹ is hydrogen or is selected from the group consisting of halo, Ci _-6 alkyl, C _3-6 cycloalkyl, Cs.^cycloalkylCi^alkyl, C _6- i ₄ aryl, C _6- ioarylCi _-4 alkyl, heteroaryl, halo-(CH ₂ CH ₂ ),. ₆ -; halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ )i _-6 -, halo-CH ₂ CH ₂ - (OCH ₂ CH ₂ ), _-6 O(CO)- and halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ), _-6 (CO)-;

each R ¹⁰ is independently H or Ci- ₆ alkyl;

R ¹¹ is a hydrogen or is selected from the group consisting of halo, C]. ₆ alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi _-5 alkyl, C ₆ -i ₄ aryl, C ₆ -ioarylCi- ₄ alkyl, heteroaryl, halo-(CH ₂ CH ₂ ),. ₆ -; halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _1-6 -, halo-CH ₂ CH ₂ - (OCH ₂ CH ₂ ) _I-6 O(CO)- and halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ )i _-6 (CO)-; provided that at least one of R ¹ to R ¹ ' comprises a radiolabel, as defined herein; wherein the radiolabel comprises a radionuclide selected from the group consisting of ¹¹ C, ¹³ N, ¹⁵ O, ¹⁸ F, ¹²³ 1, ¹²⁴ I, ¹²⁵ I, ¹³¹ I and ⁷⁷ Br; and pharmaceutically acceptable salts thereof.

30. The compound of Claim 29, wherein:

X is a bond or is selected from the group consisting of Ci _-6 alkylenyl, -C(O)-, -C(O)O-;

Y is a bond or is selected from the group consisting of amino, halo, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , haloC,- ₆ alkyl, perhaloC,- ₆ alkyl, Ci_ ₆ alkyl, C _3-6 cycloalkyl, C ₃ .i ₂ cycloalkylCi- ₅ alkyl, C _6- i ₄ aryl, C _6- ioarylCi- ₄ alkyl, heteroaryl, Ci.salkoxy, H(OCH ₂ CH ₂ ), _-6 O-, C, _-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-Ci _-5 alkoxy, halo-Ci _-3 alkyl(OCH ₂ CH ₂ )i- ₆ O- and halo-CH ₂ CH ₂ O-;

R ⁵ and R ⁶ are each independently hydrogen or are each independently selected from the group consisting of amino, halo, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , - C(S)NH ₂ , halo-Ci- ₆ alkyl, perhaloCi- ₆ alkyl, Ci_ ₆ alkyl, C _3-6 cycloalkyl, C ₃ -i ₂ cycloalkylCi- ₅ alkyl, C _6- i ₄ aryl, C ₆ _ioarylCi _-4 alkyl, heteroaryl, Ci _-5 alkoxy, H(OCH ₂ CH ₂ ) _L6 O-, C _1-3 alkyl(OCH ₂ CH ₂ ) _1-6 O-, halo-C _1-5 alkoxy, halo-Ci _-3 alkyl(OCH ₂ CH ₂ ) _1-6 O-, halo-CH ₂ CH ₂ O-, C ₃ . ₆ cycloalkoxy, C ₃ .i ₂ cycloalkylCi- ₅ alkoxy, heteroarylC _2-5 alkoxy, C _6- i ₄ aryloxy, C _6- ioarylCi_4alkoxy, heteroaryloxy, C i _-5 alkylNR ¹⁰ C(O)-, (C _r6 alkyl) ₂ NC(O)CH(C ₁ . ₅ alkyl)-, halo- C i - ₆ alkylNR ' ⁰ C(O)CH(C , _-5 alkyl )-, halo-C , - ₆ alkyl OC(O)CH(C , _-5 alky 1)-, haloes kylNR ¹⁰ C(O)-, C _1-5 alkylNR ¹⁰ C(O)O-, Ci _-5 alkylC(O)-, C _1-5 alkylC(O)O-, C _6- i ₀ arylC(O)- and C _6-10 arylC(O)O-;

R ⁹ is hydrogen or is selected from the group consisting of halo, Ci _-6 alkyl, C ₃ . ₆ cycloalkyl, C ₆ .i ₄ aryl, C _6-1 oarylCi. ₄ alkyl, halo- (CH ₂ CH ₂ )L ₆ -; halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ), _-6 -, halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _1-6 O(CO)- and halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _1-6 (CO)-; and

R ^{1 1} is absent, a hydrogen or is selected from the group consisting of halo, Ci_ ₆ alkyl, C _3-6 cycloalkyl, C _3- i ₂ cycloalkylCi _-5 alkyl, C ₆ -i ₄ aryl, C _6- ioarylC _!-4 alkyl, halo- (CH ₂ CH ₂ ) , . ₆ -; halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) , _-6 -, halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) , - ₆ O(CO)- and halo-CH ₂ CH ₂ -(OCH ₂ CH ₂ )i- ₆ (CO)-;

31. The compound of Claim 29, wherein:

X is a bond or is selected from the group consisting of Ci _-6 alkylenyl, -C(O)-, -C(O)O-;

Y is a bond or is selected from the group consisting of amino, halo, hydroxyl, -SR ¹⁰ , -C(O)NH ₂ , -C(S)NH ₂ , halo-C _r6 alkyl, perhaloC,- ₆ alkyl, C _1-6 alkyl, C ₃ . ₆ cycloalkyl, C ₃ _i ₂ cycloalkylCi- ₅ alkyl, C ₆ -i ₄ aryl, C _6- ioarylC _1-4 alkyl, heteroaryl, C _)-5 alkoxy, H(OCH ₂ CH ₂ ) _1-6 O-, Ci _-3 alkyl(OCH ₂ CH ₂ )i _-6 O-, halo-Ci _-5 alkoxy, halo-Ci _-3 alkyl(OCH ₂ CH ₂ ) _1-6 O-, halo-CH ₂ CH ₂ O-, C _3-6 cycloalkoxy, C _3- i ₂ cycloalkylCi_ ₅ alkoxy, heteroarylC _2- salkoxy, C _6- ] ₄ aryloxy, C _ό -ioarylC^alkoxy and heteroaryloxy when R ¹¹ is absent; and

R ⁵ and R ⁶ are each independently hydrogen or are each independently selected from the group consisting of halo-Ci _-5 alkoxy, halo-C , _-3 alkyl(OCH ₂ CH ₂ ) , _-6 O-, halo-CH ₂ CH ₂ O-, 1IaIo-CH ₂ CH ₂ -(OCH ₂ CH ₂ ) _{! -6} O-, halo-C-ealkylNR'V^C^CsalkyO-. halo-C-ealkylOC^CH^ _L salkyO- and halo-Ci- ₅ alkylNR ¹⁰ C(O)-.

32. A pharmaceutical composition for in vivo imaging of amyloid deposits, comprising (a) a compound of any one of Claims 1 to 31 and (b) a pharmaceutically acceptable carrier.

33. A method of diagnosing Alzheimer's Disease or a predisposition thereto in a mammal, the method comprising: a) administering to the mammal a diagnostically effective amount of a radiolabeled compound, wherein the compound passes the blood-brain barrier and preferentially binds to a soluble AD oligomers, polymers and fibrils in a brain tissue and wherein the compound is selected from the group consisting of radiolabeled flavones, coumarins, carbazoles, quinolinones, chromenones, imidazoles and triazoles and their derivatives; b) allowing the compound to distribute into the brain tissue; and

c) imaging the brain tissue, wherein an increase in binding of the compound to the brain tissue compared to a normal control level of binding indicates that the mammal is suffering from or is at risk of developing Alzheimer's Disease.

34. The method of Claim 33, wherein the compound is a compound of any one of Claim 1 to 31.

35. A method of diagnosing Alzheimer's Disease or a predisposition thereto in a mammal, the method comprising: a) administering to the mammal a diagnostically effective amount of a radiolabeled compound or composition of any one of Claim 1 to Claim 32, wherein the compound passes the blood-brain barrier and preferentially binds to a soluble AD oligomers, polymers and fibrils in a brain tissue; b) allowing the compound to distribute into the brain tissue; and c) imaging the brain tissue, wherein an increase in binding of the compound to the brain tissue compared to a normal control level of binding indicates that the mammal is suffering from or is at risk of developing Alzheimer's Disease.

36. The method of Claim 35, wherein the radiolabeled compound preferentially binds to fibrils.

37. The method of Claim 35, wherein the brain tissue comprises a frontotemporal region or the hippocampal region.

38. The method of Claim 35, wherein the increase in binding is at least 10% greater than said normal control value.

39. The method of any of Claim 33 to Claim 38, wherein the compound is administered by intravenous injection.

40. A method for detecting Alzheimer's Disease or a predisposition thereto in a living brain of a mammal, the method comprising: a) administering the mammal with a diagnostically effective amount of a radiolabeled compound that passes the blood-brain barrier and preferentially binds to a soluble AD oligomers, polymers and fibrils in the brain, wherein the detectably- labeled compound is a compound of any one of Claim 1 to Claim 31 ;

b) allowing the compound to distribute into the brain tissue; and c) imaging the brain tissue, wherein an increase in binding of the compound to the brain tissue compared to a normal control level of binding indicates that the mammal is suffering from or is at risk of developing Alzheimer's Disease.

41. A method for detecting Alzheimer's Disease or a predisposition thereto in a living brain of a mammal, the method comprising: a) administering the mammal with a diagnostically effective amount of a radiolabeled compound of any one of Claim 1 to Claim 31 , wherein the compound passes the blood-brain barrier and preferentially binds to a soluble AD oligomers, polymers and fibrils in the brain; b) allowing the compound to distribute into the brain tissue; and c) imaging the brain tissue, wherein an increase in binding of the compound to the brain tissue compared to a normal control level of binding indicates that the mammal is suffering from or is at risk of developing Alzheimer's Disease.

42. A method of diagnosing Alzheimer's Disease or a predisposition thereto in a mammal, the method comprising: a) administering to the mammal a diagnostically effective amount of a radiolabeled compound, wherein the compound passes the blood-brain barrier and preferentially binds to a soluble or insoluble AD oligomers, polymers, fibrils, hyperphosphorylated tau, neurofibrillary tangles, paired helical filaments and/or neurotoxic soluble oligomers in a brain, and wherein the radiolabeled compound is a compound of any one of Claim 1 to 31 ; and

(b) employing a nuclear imaging technique selected from the group consisting of positron emission tomography (PET) and single photon emission computed tomography (SPECT) for monitoring or visualizing a distribution of the radiolabeled compound within the brain or within a portion thereof.

43. The method of Claim 42 wherein the radiolabeled compound or a derivative thereof, is a compound of any one of Claim 1 to Claim 31.

44. A method for treating a disease or condition, in a mammal in need thereof, selected from the group consisting of anxiety, depression, schizophrenia, Alzheimer's Disease, stress-related disease, panic, a phobia, obsessive compulsive

disorder, obesity, post-traumatic stress syndrome, or epilepsy comprising administering to the mammal a therapeutically effective amount of a compound of any one of Claim 1 to 31.

45. The method of Claim 44, wherein the compound is a non-radiolabeled compound of any one of Claim 1 to Claim 31.

46. The method of Claim 44, wherein the compound is administered rectally, topically, orally, sublingually or parenterally.

47. The method of Claim 44, wherein the compound is administered from about 0.001 to about 100 mg/kg of body weight of the mammal per day.

48. The method of Claim 44, wherein the compound is administered from about 0.1 to about 50 mg/kg of body weight of the mammal per day.