Selected 68Ga-siderophores versus 68Ga-colloid and 68Ga-citrate: biodistribution and small animal imaging in mice

Abstract

Background: 68Ga-triacetylfusarinine C (TAFC) and 68Ga-ferrioxamine E (FOXE) show great potential to be used as highly sensitive and selective tracers for Aspergillus infection imaging. Here we report on a comparison of the ex vivo biodistribution and small animal imaging of 68Ga-TAFC and 68Ga-FOXE versus 68Ga-colloid and 68Ga-citrate as unspecific control in mice. Methods: The radiochemical purity of tested 68Ga labelled tracers was determined by RP-HPLC or ITLC-SG. Ex vivo biodistribution was studied in normal DBA/2 mice 30 min and 90 min p.i. Static and dynamic imaging were performed using µPET/CT. Results: 68Ga-TAFC and 68Ga-FOXE showed rapid renal excretion and low blood values even 90 min p.i. 68Ga-TAFC showed almost no retention in other organs while 68Ga-FOXE displayed some uptake in gastrointestinal tract. 68Ga-colloid and 68Ga-citrate revealed significantly different ex vivo biodistribution. 68Ga-colloid showed pronounced radioactivity retention in the liver, while 68Ga-citrate displayed high blood values and significant retention of radioactivity in highly perfused organs. Conclusions: From the results, both 68Ga-TAFC and 68Ga-FOXE have excellent and significantly different in vivo behaviour compared to 68Ga-colloid and 68Ga-citrate. 68Ga-TAFC in particular confirmed its great potential use as a specific tracer for Aspergillus infection imaging.

Keywords

• gallium-68
• siderophores
• colloid
• citrate
• µpet imaging
• aspergillosis