Synthesis, tissue distribution and tumor uptake of 99mTc- and 67Ga- Tetrasulfophthalocyanine

Complexes of tetrasulfophthalocyanine with ${}^{\mathrm{99m}}\text{Tc}$, ⁶⁹Ga and ⁶⁷Ga were prepared by the condensation of sulfophthalic acid with the appropriate metal-species. The Ga-complex was also obtained by exchange of the central hydrogens of the empty tetrasulfophthalocyanine. The labeled complexes were purified by thin layer chromatography and characterized by their chromatographic properties. Their biodistribution in rabbits and tumor-bearing rats revealed that most of the radioactivity accumulated in the kidneys, liver, ovaries, adrenals and spleen. Comparison of these distribution pattern with those of [${}^{\mathrm{99m}}\text{Tc}$]pertechnetate and ⁶⁷Ga-citrate confirmed the in vivo stability of the labeled complexes. The ⁶⁷Ga-complex reached better tumor-to-blood and tumor-to-muscle ratios than ⁶⁷Ga-citrate.