To explore the relation of the radiochemical purity and in vivo imaging effect of ⁶⁸Ga-1, 4, 7, 10-tetraazacyclododecane-1, 4, 7, 10-tetraacetic acid (DOTA)-D-phe1-Tyr3-Thr8-octreotide (TATE) injection.

High performance liquid chromatography (HPLC) and thin-layer chromatography (TLC) methods were established to determine ⁶⁸Ga-DOTATATE, ⁶⁸Ga³⁺ , ⁶⁸Ga in colloidal form and ⁶⁸Ga-DOTA-D-Phe1-Tyr3-Thr8-dethreonine-octreotide (heptapeptide) and to study the influence of precursor purity on radiochemical purity of labelled products. The uptake of ⁶⁸Ga-DOTATATE injection with different radiochemical purities was investigated in nude mice bearing AR42J cells by microPET imaging and the tumor target/non-target (T/NT) value was calculated. One-way analysis of variance and Pearson correlation analysis were used to analyze the data.

The contents of ⁶⁸Ga³⁺ and ⁶⁸Ga in colloidal form were not related with precursor purity (r values: 0.385, 0.497, P values: 0.306, 0.137), while the content of ⁶⁸Ga-DOTA-heptapeptide was positively related with the purity of DOTA-heptapeptide (r=0.957, P<0.001). The radiochemical purities of ⁶⁸Ga-DOTATATE injection were (87.0±2.3)%, (86.8±0.8)% and (94.0±3.1)% when the DOTATATE purities were 90.9%, 91.6% and 99.2%, respectively. The results of microPET imaging showed that the tumor uptake was positively related with the radiochemical purity of ⁶⁸Ga-DOTATATE injection (r=0.828, P<0.001), and the T/NT values of ⁶⁸Ga-DOTATATE injection with radiochemical purities of 95.7%, 85.8%, 84.5% and 79.9% were 21.25±8.84, 8.50±1.51, 11.38±1.65 and 6.01±0.99, respectively (F=11.48, P=0.001).

The radiochemical purity of ⁶⁸Ga-DOTATATE injection is impacted by the purity of labelled precursor and manufacturing processes and is related with the imaging effect in vivo.

Organometallic compounds; Gallium radioisotopes; Quality control; Chromatography, high pressure liquid; Chromatography, thin layer; Positron-emission tomography; Pancreatic neoplasms; Mice, nude