Altered [(99m)Tc]Tc-MDP biodistribution from neutron activation sourced (99)Mo

Given potential worldwide shortages of fission sourced (99)Mo/(99m)Tc medical isotopes there is increasing interest in alternate production strategies. A neutron activated (99)Mo source was utilized in a single center phase III open label study comparing (99m)Tc, as (99m)Tc Methylene Diphosphonate ([(99m)Tc]Tc-MDP), obtained from solvent generator separation of neutron activation produced (99)Mo, versus nuclear reactor produced (99)Mo (e.g., fission sourced) in oncology patients for which an [(99m)Tc]Tc-MDP bone scan would normally have been indicated. Despite the investigational [(99m)Tc]Tc-MDP passing all standard, and above standard of care, quality assurance tests, which would normally be sufficient to allow human administration, there was altered biodistribution which could lead to erroneous clinical interpretation. The cause of the altered biodistribution remains unknown and requires further research.