Synthesis and preliminary evaluation of [1-11C]hexanoate as a PET tracer of fatty acid metabolism.

The potential of [1-11C]hexanoate (11C-HA) as a radiopharmaceutical assessing fatty acid metabolism of the myocardium and brain tissues by PET studies was evaluated. 11C-HA was synthesized by the Grignard reaction of pentylmagnesium bromide and 11CO2. 11C-HA, [1-14C]acetate and [3H]deoxyglucose were simultaneously injected i.v. into mice, and the tissue distribution of the three radionuclides was measured. In the heart, high uptake and rapid clearance of 11C and 14C was found. The brain uptake of 11C was twice as high as that of 14C, and both 11C and 14C decreased slowly compared to the heart. The level of 3H increased with time in both the heart and brain. In fasting conditions, the uptake of 11C by the heart was enhanced and the level of 3H decreased with time. The brain uptake of 11C and 3H was also enhanced. The fasting conditions did not affect the distribution of 14C. The radiation absorbed dose of 11C-HA was also estimated.