201Tl-diethyldithiocarbamate: a possible radiopharmaceutical for brain imaging

For estimating regional brain perfusion with a gamma camera lipophilic radiopharmaceuticals are required. This paper describes the development of 201Tl-diethyldithiocarbamate (201TlDDC). First the compound NaDDC was tested for stability and an assay was developed. Next the 201TlDDC complex was prepared and checked for lipophilicity and stability by paper chromatography. A scintigraphic pilot study using this agent in a rabbit showed considerable brain uptake, compared to 201TlCl. Finally we performed a study in rats on the distribution of 201TlDDC in different organs. The results confirmed the lipophilicity of the agent. Within the first hour the percentage of injected dose per gram tissue was 2.73% in the cerebrum and 1.35% in the cerebellum. These data are in good agreement with some other agents used for assessment of brain blood flow.