Synthesis and Bioimaging of Positron‐Emitting 15O‐Labeled 2‐Deoxy‐D‐glucose of Two‐Minute Half‐Life

In positron emission tomography (PET), which exploits the affinity of a radiopharmaceutical for the target organ, a systematic repertoire of oxygen‐15‐labeled PET tracers is expected to be useful for bioimaging owing to the ubiquity of oxygen atoms in organic compounds. However, because of the 2‐min half‐life of ¹⁵O, the synthesis of complex biologically active ¹⁵O‐labeled organic molecules has not yet been achieved. A state‐of‐the‐art synthesis now makes available an ¹⁵O‐labeled complex organic molecule, 6‐¹⁵O]‐2‐deoxy‐D ‐glucose. Ultrarapid radical hydroxylation of 2,6‐dideoxy‐6‐iodo‐D ‐glucose with molecular oxygen labeled with ¹⁵O of two‐minute half‐life provided the target ¹⁵O‐labeled molecule. The labeling reaction with ¹⁵O was complete in 1.3 min, and the entire operation time starting from the generation of ¹⁵O‐containing dioxygen by a cyclotron to the purification of the labeled sugar was 7 min. The labeled sugar accumulated in the metabolically active organs as well as in the bladder of mice and rats. ¹⁵O‐labeling offers the possibility of repetitive scanning and the use of multiple PET tracers in the same body within a short time, and hence should significantly expand the scope of PET studies of small animals.