ABSTRACT
Objective: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. Methods:High performance liquid chromatography (HPLC) and thin-layer chromatography (TLC) methods were established to determine 68Ga-DOTATATE, 68Ga 3+ , 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. Results:The contents of 68Ga 3+ 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). Conclusion: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.