4′-[methyl-11C]-thiothymidine

4′-[methyl-11C]-thiothymidine (also known as 11C-4DST) is a radiolabeled thymidine analog used as a positron emission tomography (PET) tracer for imaging cellular proliferation. The compound is labeled with carbon-11 at the methyl group and features a sulfur atom replacing the oxygen at the 4' position of thymidine, making it structurally similar to natural thymidine but resistant to degradation by thymidine phosphorylase. After administration, it is incorporated into DNA in proliferating cells, allowing noninvasive visualization and quantification of cell proliferation in vivo. This property makes it particularly useful for imaging tumor growth and aggressiveness in cancers such as non–small cell lung cancer and high-grade gliomas[2][3]. Its uptake reflects activity of S-phase–specific enzymes like thymidine kinase, which are upregulated during DNA synthesis[2].

Other names

methyl-[11C]-4'-thiothymidine[methyl-^11C]thiothymidine