Preparation and microPET imaging of somatostatin receptor antagonist 68 Ga-NOTA-JR11 / 中华核医学与分子影像杂志

ABSTRACT

Objective To prepare a novel somatostatin receptor (SSTR) antagonist 68Ga-1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA)-JR11 (Cpa-c(D-Cys-Aph(Hor)-D-Aph(Cbm)-Lys-Thr-Cys)-D-Tyr-NH2 ) tracer and observe its biodistribution and microPET imaging in mice. Methods One ml HCl (0.05 mol/L) containing 68GaCl3(148 MBq) was added into 65μl NaAc (1 mol/L) and 4μg NOTA-JR11. The mixture reacted at 95 ℃ for 15 min, and then was purified with Sep-Pak? C18 Light column to obtain 68 Ga-NOTA-JR11. 68 Ga-NOTA-JR11 was subjected to quality control analysis including radiochemical purity and in vitro stability by radio-high performance liquid chromatography. Biodistribution of 68Ga-NOTA-JR11 (0.37 MBq) in BALB/c mice (n=9) at 5, 30, 60 min postinjection were observed (n=3 for each time point), and the percentage activity of injection dose per gram of tissue (％ID/g) was calculated. 68Ga-NOTA-JR11 (14.8 MBq) microPET imaging of BALB/c mice (n=1) at 60 min postinjection was observed. Results 68 Ga-NOTA-JR11 was obtained successfully within 15 min, with yielding rate of 90％, radiochemical purity of more than 99％, and specific activity of 6. 10 GBq/μmol. The tracer showed excellent stability ( radio-chemical purity:95％) in different buffers within 150 min. The biodistribution was basically consistent with microPET imaging results. 68 Ga-NOTA-JR11 was metabolized through the kidneys and had low uptake in the liver ((0.75±0.26) ％ID/g) at 60 min postinjection. Conclusions 68 Ga-NOTA-JR11 can be prepared rapidly, with high yielding rate and radiochemical purity. Biodistribution and imaging results provide basic information for the further study of somatostatin receptor imaging in neuroendocrine tumors.