Department of Nuclear Medicine/PET Center, Zentralklinik Bad Berka, 99437 Bad, Berka, Germany.
Nucl Med Biol. 2011 Jul;38(5):653-8. doi: 10.1016/j.nucmedbio.2011.01.006. Epub 2011 Mar 30.
O-(2-[(18)F]fluoroethyl)-L-tyrosine (FET) is widely used as a positron emission tomography tracer for brain tumors. Usually, a high-performance liquid chromatography (HPLC) purification at the end of the two-step synthesis is applied. In this work, we report an automatic radiosynthesis of FET with a purification procedure based on standard cartridges.
O-(2-[(18)F]fluoroethyl)-L-tyrosine was prepared by [(18)F]fluoroethylation of L-tyrosine by a two-step synthesis using a modified [(11)C]methionine module (Nuclear Interface). In the first reaction step, we synthesized [(18)F]fluoroethyltosylate starting from [(18)F]fluoride. After a purification step, L-tyrosine was [(18)F]fluoroethylated with [(18)F]fluoroethyltosylate. The final reaction mixture was purified by means of solid phase extraction. The FET was trapped on an SCX cartridge, eluted with saline solution and trapped again on an HRX cartridge. For a second purification step, the FET was eluted from the HRX cartridge with ammonium acetate buffer and collected on two SCX cartridges followed by a washing step with water. The final product was eluted with saline solution and neutralised with 450 μl NaHCO(3) solution (8.4%).
The synthesis was finished after 50 min and delivered the FET in a range of 3-16 GBq. The synthesis typically yielded 41% (21 experiments) of FET (d.c.) without an HPLC purification step. The radiochemical purity ranged between 97% and 100%.
We present a radiosynthesis of FET where the usually used HPLC purification procedure has been substituted by a purification step based on standard cartridges. This method is useful for automatic modules without an expensive HPLC purification unit and for the routine production of FET.
O-(2-[(18)F]氟乙基)-L-酪氨酸（FET）被广泛用作脑肿瘤的正电子发射断层扫描（PET）示踪剂。通常，在两步合成结束时应用高效液相色谱（HPLC）纯化。在这项工作中，我们报告了一种基于标准试剂盒的自动合成 FET 的方法，该方法无需进行 HPLC 纯化。
O-(2-[(18)F]氟乙基)-L-酪氨酸是通过两步合成方法用 L-酪氨酸进行[(18)F]氟乙基化制备的，使用改良的[(11)C]蛋氨酸模块（核界面）。在第一反应步骤中，我们从[(18)F]氟化物开始合成[(18)F]氟乙基对甲苯磺酸酯。经过纯化步骤后，用[(18)F]氟乙基对甲苯磺酸酯对 L-酪氨酸进行[(18)F]氟乙基化。最终的反应混合物通过固相萃取进行纯化。FET 被捕获在 SCX 试剂盒上，用生理盐水洗脱，然后再次捕获在 HRX 试剂盒上。对于第二步纯化，FET 从 HRX 试剂盒中用乙酸铵缓冲液洗脱，并收集在两个 SCX 试剂盒上，然后用水进行洗涤步骤。最后用生理盐水洗脱，并用 450μl NaHCO(3)溶液（8.4%）中和。
合成在 50 分钟后完成，提供了 3-16GBq 范围内的 FET。在没有 HPLC 纯化步骤的情况下，该合成通常产生 41%（21 个实验）的 FET（直流）。放射化学纯度在 97%至 100%之间。
我们提出了一种 FET 的放射合成方法，其中通常使用的 HPLC 纯化步骤已被基于标准试剂盒的纯化步骤所取代。该方法适用于没有昂贵的 HPLC 纯化单元的自动模块，也适用于 FET 的常规生产。
