68Ge/68Ga发生器的临床应用

Application of the 68Ge/68Ga Generator in Clinic

  • 摘要: 对新型68Ge/68Ga发生器的最佳淋洗时间、最佳峰段以及不同缓冲液对68Ga显像及生物分布的影响进行研究,为动物实验和临床应用提供参考。采用4 mL 0.05 mol/L HCl淋洗740 MBq ITG 68Ge/68Ga发生器,首次淋洗后分别隔2、4、6、8、10、12、14 h再次淋洗,记录放射性活度;先以每段0.5 mL收集淋洗液,在比活度较高段以每0.1 mL收集淋洗液,记录放射性活度;分别用乙酸钠、NaOH、4-羟乙基哌嗪乙磺酸(HEPES)调节68Ga3+溶液pH,在正常小鼠体内行microPET显像。结果表明:在淋洗4 h后,放射性活度可达平衡时的91%;最佳峰段为2~3 mL,放射性活度峰段的0.1 mL可收集22 MBq的68Ga3+68Ga3+在血液中摄取值高,1 h仍有6.9%ID/g,表明游离的68Ga3+可能会影响图像的对比度,需要在标记放射性药物后去除残余的游离68Ga3+;膀胱的放射性摄取高,提示68Ga3+通过泌尿系统排泄;乙酸钠、NaOH、HEPES调节pH后对68Ga在正常小鼠体内显像及生物分布均无统计学差异(P>0.05)。新型68Ge/68Ga发生器操作简便,每4 h即可淋洗一次,淋洗液的峰段在2~3 mL,建议临床采用乙酸钠缓冲液。

     

    Abstract: ITG 68Ge/68Ga generator allows for dilute HCl to effectively elute 68Ga3+ without metal impurities. The impact of the optimal elution time, the best peak segment and the effects of different buffers on the imaging and biodistribution of the 68Ga were explored with the ITG 68Ge/68Ga generator. According to the manufacturer protocol, a 740 MBq self-shielded 68Ge/68Ga generator was eluted with 4 mL of 0.05 mol/L HCl. After the beginning of elution, the generator was eluted again at 2, 4, 6, 8, 10, 12, 14 hours to record radioactivity. The 68Ga was eluted with HCl in each fraction of 0.5 mL, then eluted with every 0.1 mL in the dense fractions and the radioactivity was recorded. MicroPET imaging and biodistribution were performed in normal mice after adjusting the pH of 68Ga3+ solution with sodium acetate, NaOH and HEPES separately. The results showed that 4 hours post elution, 91% of the maximum achievable radioactivity was accumulated. The best peak was at 2.3 mL and the radioactivity of the top fraction (0.1 mL) was 22 MBq. The uptake of 68Ga3+ radioactivity was 6.9%ID/g in the blood at 1 hour post injection, suggesting that purity of a tracer was essential because free 68Ga3+ may affect the contrast of the image and dection of tumors. The radioactivity uptake of the bladder was high, suggesting that the 68Ga3+ was metabolized by the urinary system. There was no significant difference in the 68Ga3+ imaging and biodistribution as using sodium acetate, HEPES and NaOH as buffer solution (P>0.05). The results showed that ITG 68Ge/68Ga generator was simple and convenient for manual operation. The generator could be eluted every 4 hours and the best peak segment was at 2.3 mL. Sodium acetate seems to be the most appropriate buffer in clinic.

     

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