Biomedical Imaging Research Center, University of Fukui, Fukui 910–1193, Japan.
Inhalational O-15 methods are the norms to characterize the pathophysiological status of brain tissue. Limited utilization of O-15 gas as it has to be passed through a line, risk of exposure to high radiation doses in the trachea and lungs and possible risk of leakages prompted us to devlop an injectable O-15 system using Hemoglobin-vesicle (HbV) for diagnostic purposes with a potential for human use as we intend to eliminate the use of artificial lungs.
Hemoglobin-vesicle (HbV) provided by Oxygenix Co. Ltd. Japan were labeled with O-15 by direct bubbling. Since the labeling efficiency was not good enough we also tried vortex method in order to increase the labeling efficiency. Radioactivity was measured after labeling and before injecting into the rat and labeling efficiency was calculated after decay correction. The O-15 labeled Hemoglobin-vesicle (HbV) were injected into the rat and serial transmission PET scans were performed.
The labeling efficiency calculated for direct bubbling was 11% which got increased upto 42% when vortex was used. The images obtained after reconstruction clearly showed the presence of activity in the brain, heart and lungs region. This proves that HbV could successfully bind O-15 and was able to release it in vivo.
Intravenously injectable oxygen-15 could be prepared with sufficient radioactivity and there is no risk of infection and acute response. The Hemoglobin-vesicles (HbV) are stable for transient period of time and hence can be used as carrier of injectable O-15 form.
Artificial red blood cells, Hemoglobin-vesicle (HbV), Positron emission tomography, Injectable Oxygen-15, Labelling efficiency
