title: The normal pituitary examined with positron emission tomography and (methyl-11C)-L-methionine and (methyl-11C)-D-methionine.
abstract: Four patients with radiologically normal pituitary gland were examined with positron emission tomography after the administration of (methyl-11C)-L-methionine. On a following day the examination was repeated with (methyl-11C)-D-methionine. The accumulation rate of L-methionine in the pituitary was measured, giving a value that was about twice that of normal brain tissue. The accumulation rate of D-methionine in the pituitary was almost a factor of 10 lower than that of L-methionine. In the normal brain tissue that ratio was 2.3. The study clearly indicates that the methionine uptake in the pituitary is stereospecific. 11C-D-methionine is freely distributed in the tissue without entrapment, whereas 11C-L-methionine is irreversibly bound. It is concluded that PET with 11C-L-methionine can be used to study amino acid utilization in the pituitary.
mesh_terms: D000328:Adult; D001932:Brain Neoplasms / Q000000981:diagnostic imaging; D002250:Carbon Radioisotopes; D005260:Female; D005910:Glioma / Q000000981:diagnostic imaging; D006801:Humans; D007700:Kinetics; D008715:Methionine / Q000031:analogs & derivatives*; D010902:Pituitary Gland / Q000000981:diagnostic imaging*; D013237:Stereoisomerism; D014055:Tomography, Emission-Computed / Q000379:methods*
chemical_list: D002250:Carbon Radioisotopes; D008715:Methionine; C038344:methionine methyl ester