Scaled-up radiolabelling of DOTATATE with 68Ga eluted from a SnO2-based 68Ge/68Ga generator

A scaled-up radiolabelling and improved post-labelling purification procedure for [68Ga]DOTATATE is reported, using a more than 1 year old SnO2-based 1850 MBq 68Ge/68Ga generator (initially double-loaded with 3700 MBq 68Ge) as a source of ionic 68Ga. The elution method of choice comprised elution with 0.6 M HCl in a single 4 mL fraction, containing up to 95% of the total eluted 68Ga activity. The unpurified fraction was directly used for labelling after pH adjustment with 2.5 M sodium acetate. Labelling efficiencies were determined at 90–95 °C at various reaction times and reaction volumes of up to 5.7 mL, using either 30 μg or 50 μg DOTATATE. Only the latter amount resulted in consistently high labelling efficiency in excess of 95%. Post-labelling purification, carried out on Sep-Pak C18, showed that 50% ethanol in saline was a superior desorption eluant than 100% ethanol. The highest and most consistent decay-corrected radiochemical yields (89%) were obtained using 50 μg DOTATATE and a 20 min reaction time.

► 68Ga-labelling of DOTATATE with SnO2-based 68Ge/68Ga generator eluates was examined.
► pH of the non-concentrated/unpurified eluates was adjusted with 2.5 M NaOAc.
► Consistently good labelling results were obtained with 50 μg DOTATATE in 5.6 mL.
► Better Sep-Pak C18 product desorption eluant was 50 % ethanol in saline.
► Described methodology delivers nearly 90% decay-corrected radiochemical yields.