Preparation of 124I, Antibody Labeling and Micro-PET/CT Imaging of Labeled Compounds

Abstract

To provide a method for the production of 124I by using a medical cyclotron and the method of 124I labeling, 124I was prepared using a nuclear reaction of 124Te (p，n) 124I. Firstly，a 124TeO2/Al2O3 target was obtained by pressing，and then bombarded with a cyclotron for 3-8 hours. After 12 hours，impurity nuclides produced by the side reaction were removed. Finally，a Na124I solution was obtained by iodine sublimation radiochemical separation method. Analyze the purity of Na124I and label it with anti-mesothelin (MSLN) antibody，then inject it into the tail vein of KM mice to observe the distribution of 124I-anti-MSLN. The obtained 124TeO2/Al2O3 target was bombarded with 12.5 MeV energy and 20 μA proton beam to obtain 340.4-1121.1 MBq nuclide products，and after purification，274.2-758.5 MBq of high-purity Na124I solution was obtained. The final radioactive concentration of the obtained Na124I solution was greater than 54840 Bq/μL. Using the Na124I solution to label an anti-MSLN antibody，124I-anti-MSLN probe with a radiochemical purity greater than 99% was obtained. The probe was injected into KM mice via the tail vein，and significant uptake of the probe was observed in the thyroid region of the mice through Micro-PET/CT imaging. This uptake can be blocked by feeding 0.5% KI solution 3 days in advance，and the metabolic behavior conforms to the metabolic pattern of the 124I labeled antibody probe in KM mice. This study summarized the purification of 124I samples of 25 batches in our unit，and tthe equipment and methods involved in the purification process and the use of Na124I after purification were summarized. In order to provide reference for the production and efficient purification of 124I. The results showed that the purified 124I had high nuclear purity and chemical purity，which met the requirements of radiolabeling. The average recovery rate was higher than 70%，and the automatic purification process was safe and reliable.

Keywords

• solid target radionuclide
• iodine-124
• tellurium-124 solid target
• 124i auto-purification system
• micro-pet/ct