1. A pharmaceutical composition suitable for in vivo diagnostic use that contains a pharmaceutically acceptable salt of a ShK polypeptide that has the sequence Arg-Ser-Cys-Ile-Asp-Thr-Ile-Pro-Lys-Ser-Arg-Cys-Thr-Ala -Phe-Gln-Cys-Lys-His-Ser-Xaa-Lys-Tyr-Arg-Leu-Ser-Phe-Cys-Arg-Lys-Thr-Cys-Gly-Thr-Cys (SEQ ID No. 1), where said ShK polypeptide is attached to a detectable label and an organic or inorganic chemical particle that has an anionic charge and where the C-terminus is an acid or amide. 2. The composition of claim 1, wherein said detectable label is an indium-111 (In) chelate. The composition of claim 2, wherein said detectable label is a 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid chelate (DOTA) and indium-111 (In). 4. The composition of claim 1, wherein said detectable label is a gadolinium chelate (Gd). The composition of claim 4, wherein said detectable label is gadolinium (Gd) DOTA chelate. The composition of claim 1, wherein said ShK polypeptide has the sequence Tyr-AEEA-Arg-Ser-Cys-Ile-Asp-Thr-Ile-Pro-Lys-Ser-Arg-Cys-Thr-Ala-Phe-Gln-Cys- Lys-His-Ser-Met-Lys-Tyr-Arg-Leu-Ser-Phe-Cys-Arg-Lys-Thr-Cys-Gly-Thr-Cys-NH (ShK-198) and a detectable label is on the amino terminus. 7. The composition of claim 6, wherein the detectable label is a chelate of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) and indium-111 (In). A pharmaceutical composition that contains a pharmaceutically acceptable salt of a ShK polypeptide that has the sequence Arg-Ser-Cys-Ile-Asp-Thr-Ile-Pro-Lys-Ser-Arg-Cys-Thr-Ala-Phe-Gln-Cys-Lys- His-Ser-Xaa-Lys-Tyr-Arg-Leu-Ser-Phe-Cys-Arg-Lys-Thr-Cys-Gly-Thr-Cys (SEQ ID NO: 1), wherein said ShK polypeptide is attached to an organic or inorganic chemical particle which and1. Фармацевтическая композиция, подходящая для диагностического применения in vivo, которая содержит фармацевтически приемлемую соль полипептида ShK, который имеет последовательность Arg-Ser-Cys-Ile-Asp-Thr-Ile-Pro-Lys-Ser-Arg-Cys-Thr-Ala-Phe-Gln-Cys-Ly
