PET imaging and optical imaging with d-luciferin [11C]methyl ester and d-luciferin [11C]methyl ether of luciferase gene expression in tumor xenografts of living mice

New carbon-11 labeled d-luciferin analogs d-luciferin [11C]methyl ester ([11C]LMEster, [11C]1) and d-luciferin [11C]methyl ether ([11C]LMEther, [11C]2) were synthesized in 25–55% radiochemical yield. PET studies with [11C]LMEster and [11C]LMEther demonstrate a lower retention of the C-11 label at 45 min post-injection in luciferase expression tumor. Optical imaging with unlabeled substrate d-luciferin and radiotracers [11C]LMEster and [11C]LMEther gave tumor luciferase images within a few minutes of photon counting.