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

A scaled-up radiolabelling and improved post-labelling purification procedure for [Ga-68]DOTATATE is reported, using a more than 1 year old SnO2-based 1850 MBq Ge-68/Ga-68 generator (initially double-loaded with 3700 MBq Ge-68) as a source of ionic Ga-68. 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 Ga-68 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 degrees C at various reaction times and reaction volumes of up to 5.7 mL, using either 30 mu g or 50 mu g 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 mu g DOTATATE and a 20 min reaction time. (C) 2011 Elsevier Ltd. All rights reserved.