Scintigraphic study on the distribution of radiolabeled cis-diamminedichloroplatinum (II) in the tumor-bearing rabbit

To compare the distribution of cis-diamminedichloroplatinum (II) (CDDP) on scintigraphic images between intra-arterial injection with lipiodol and intravenous injection, we obtained serial scintigraphic images using radiolabeled CDDP (Pt-195m CDDP), which had a high specific activity (7.4x106Bq[200 μCi]/mg-CDDP), in the rabbit VX-2 tumor system. A dose of 9.25x106Bq(250 μCi) of Pt-195m CDDP was injected at one shot via an ear vein, while 7.4x106Bq(200 μCi) of Pt-195m CDDP mixed with 1 ml of lipiodol was injected at one shot via a saphenous artery. Mean pixel count, which was corrected for the total dose injected, in the arterially injected tumor always exceeded than that in the intravenously injected tumor. Pt-195m CDDP uptake by the rabbit tumor at 2 hr was 7.8% of the total injected dose with intravenous injection and 16.0% with intra-arterial injection. These data suggest that intra-arterial injection with lipiodol is a more useful method to increase CDDP uptake by tumors than intra-venous injection. (author)