Preparation of Ga-68-NOTA as a renal PET agent and feasibility tests in mice

Positron emission tomography (PET) may provide more accurate quantification of kidney function such as glomerular filtration rate (GFR) than gamma imaging. The purpose of these experiments was to prepare and evaluate Ga-68 complexes as potential PET agents for measurement of GFR.

We labeled EDTA, DTPA, DOTA, and NOTA with Ga-68 obtained from a Ge-68/Ga-68-generator and measured the binding to serum and red blood cells. Biodistribution study was performed in male BALB/c mice after intravenous injection together with Cr-51-EDTA as the standard for glomerular filtration rate (GFR) measurement. Animal-PET study was performed using BALB/c mice.

All the tested chelating agents except DTPA showed quantitative labeling yields (>99%). Among them, Ga-68-NOTA showed consistently low binding to both human and mouse RBC and serum protein. Biodistribution study showed no significant difference between Ga-68-NOTA and Cr-51-EDTA groups by one-way analysis of variance (ANOVA) (p>0.05). Furthermore, the GFR values obtained by Ga-68-NOTA and Cr-51-EDTA were almost same (0.26±0.04 and 0.25±0.04mL/min, respectively). Animal-PET study showed almost the same GFR (0.25mL/min) with the values obtained by biodistribution study.

We proved that an easy-to-prepare agent Ga-68-NOTA is ideal for renal PET as well as for GFR measurement.