Fig. 6.

The current toolbox of PET probes for nucleotide metabolism. Proposed matching of PET probes with deoxyribonucleoside salvage kinases. [¹⁸F]FLT, 3′-[¹⁸F]fluoro-3′ deoxythymidine (48); l-[¹⁸F]FMAU, 2′-deoxy-2′-[¹⁸F]fluoro-5-methyl-1-β-l-arabinofuranosyluracil (47, 49); d-[¹⁸F]FMAU, 2′-deoxy-2′-[¹⁸F]fluoro-5-methyl-1-β-d-arabinofuranosyluracil (50, 51). Potential applications for these probes, as well as anatomical sites of preferential accumulation in healthy volunteers, are indicated. *, [¹⁸F]FLT accumulation in the liver reflects probe glucuronidation (52). N.D., not determined; PD, pharmacodynamic; PK, pharmacokinetic. **, [¹⁸F]F-AraG uptake may also reflect dCK activity.