Development of 68 Ga labeled human serum albumin for blood pool imaging: a comparison between two ligands

PET based blood pool imaging tracers have tremendous potential for detection of vascular abnormalities. We synthesized 68Ga-1,4,7-triazacyclononane-1,4,7-triacetic acid-human serum albumin (68Ga-NOTA-HSA) (1a) towards use in blood pool imaging and compared it with 68Ga-1,4,7,10-tetraazacyclo-dodecane-1,4,7,10-tetraacetic acid-HSA (68Ga-DOTA-HSA) (2a). Both 1a and 2a had similar biodistribution profiles with ≥70% ID/g activity in blood at 2 min p.i. About 50% of initial radioactivity was retained in blood at 2 h p.i. However, the plasma stability of 1a was superior to that of 2a. Results of our study indicate that 68Ga-NOTA-HSA can be further investigated for clinical blood pool imaging applications.