We synthesized four new
tumor imaging agents, 99mTc-labeled
metalloporphyrins (99mTc-STA-R12, -STA-R21, -STA-RN101 and -ATN-12) for the
tumor imaging. We compared the differences of
tumor imaging potency among these agents in CDF1 mice implanted with colon 26
tumor.
Tumor images with these agents were obtained by using digital
gamma-camera (RC135-E, Hitachi, Tokyo) and the biodistributions were analyzed by computerized medical
radionuclide imageanalyser (RP-200, Hitachi, Tokyo). The highest
tumor organ ratio and the excellent
tumor image were obtained by 99mTc-STA-R12 (13,17-Bispropanyl
aspartic acid-3-ethenyl-8-[N,N',N",N"-tetrakis (carboxylmethyl-2,7,12,18-tetramethyl-porphyrinato]-manga nes e(III). The maximum concentration of 99mTc-STA-R12 in
tumor tissue was observed at around 120 minutes after i.v. injection. On the contrary, the uptake rates of other organs and tissues such as liver, brain, muscle, lung, bone and blood continuously decreased. The rapid accumulation of STA-R12 in
cancer tissue and the clearance from other tissue suggested a potential usefulness of this compound for
tumor imaging agent.