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.