Scintigraphy with positron-emitting compounds—I. Carbon-11 labeled thymidine and thymidylate

The in vivo distribution of 11C in normal and VX2 carcinoma-tumored rabbits has been observed with a gamma camera after i.v. doses of [11C]thymidine or [11C]thymidylate. The heart was visible immediately after injection of 11C; the image disappeared by 5 min, indicating a rapid redistribution from the blood stream. We observed a generalized distribution of 11C label with some notably “hotter” spots: tumor, bone marrow, liver. The liver, spleen and bone marrow were also visualized by 99Tcm sulfur colloid injected before the [11C]TdR or [11C]dTMP. Injection of [11C]TdR diluted with 60 times more nonradioactive TdR, 97 μmoles in all, resulted in a rapid excretion of 11C. With 4 mCi of 11C at injection time scintiphotos could be obtained up to 120 min.