Synthesis of 11C-methylated inulin as a radiopharmaceutical for imaging brain edema and pulmonary edema.

11C-methylated inulin, supposedly useful for imaging of brain edema and pulmonary edema, was prepared using cyclotron produced 11CO2. The synthesis consists of the production of 11C-methyl iodide and its coupling with inulin alkoxide sodium in dimethylsulfoxide as solvent. 11C labeled inulin was purified by alcohol precipitation. The radiochemical yield of pure 11C-inulin was 34% of 11CO2 30 min after the end of bombardment. The blood clearance and body distribution of 11C was observed in rabbits after i.v. injection of 11C-inulin. The blood clearance curve was composed of a sum of three exponential functions. The gamma camera image showed that the 11C activity in blood moved quickly to kidneys and urine and a small dose of radioactivity remained persistently in edematous tissues, i.e. the edematous lung tissues produced by oleic acid treatment.