Labelling and metabolism of methionine-methyl-11C

Abstract

Carbon 11 which is a 20.4 minutes half life isotope emitting positrons was used for methionine labelling on the methyl group by action of ¹¹C-methyl-iodide on DL or L homocysteine. With the method described, 20 to 30 mCi of ¹¹C-methyl-methionine (Specific activity 50 mCi/μM) may be obtained within 25 minutes. The 20 Mev proton beam used for ¹¹C production was 10 μA. The metabolism of ¹¹C methionine studied on mice shows a high uptake in pancreas and to a smaller extent in brain. On humans sequential images were obtained at the head level which allowed measurement of the uptake of the radio-labelled compound in the brain so as to study the radioactivity curve in different parts of the organ.