INITIAL EXPERIENCE 13N-AMMONIA APPLICATION AND PERSPECTIVES FOR ITS CLINICAL USE IN NEUROONCOLOGY
Materials and methods. A group of 19 patients with suspected of recurrent growth malignant and benign tumors and postoperative cysts on PET-CT with 13N-ammonium were examined in the postoperative period. The RPH 13N-ammoniа was injected intravenously at the dose of 350-370MBq/m2 of body surface. It is shown, that PET with 13N-ammonia allows to clearly visualize benign and malignant hypervascular tumors, as well as to assess the efficiency of their treatment. The tendency was detected for prevalence of the increased accumulation of 13N-ammonia in benign hypervascular neoplasms of a vascular line as compared to malignant tumors. That is explained by the dependence of the uptake of the drug both upon the degree of tumor vascularization and upon the presence and concentration of glutamine in tumor cells. It is stated in the paper that the level of the uptake of 13N-ammonium in the tumor is in direct ratio to its perfusion and inversely to the degree of its malignancy. In case of effective treatment the level of accumulation of 13N-ammonia in malignant tumors is nonlinearly increased since the rate of metabolic processes is decreased that leads to accumulation of glutamine, however perfusion in the tumor is also nonlinearly decreased. Conclusion. Ultrashort half-life of the radionuclide [13N] (of 9.96 min) and the low radiation exposure that occurs with intravenous introduction of 13N-ammonium create a unique opportunity for diagnosis and assessment of the efficiency of treatment of brain tumors by the method of positron emission tomography.