Precise staging of neuroendocrine tumors (NET) using positron emission tomography (PET) tracers visualizing their specific metabolic activity is of interest. Besides [F-18]FDOPA, staging NET with carbon-11 labeled 5-hydroxytryptophan (5-HTP) is reported in recent literature. We implemented the multi-enzymatic synthesis of enantiomerically pure [C-11]-L-5-HTP on a Zymark robotic system to compare both tracers in patient studies. [C-11]-5-HTP can be synthesized in up to 24% radiochemical yields (EOB). Average specific activity is 44000 GBq/mmol in ca. 50 min from [C-11]methyl iodide in radiochemical purities > 99 %. The synthesis of 5-HTP is difficult due to its multi-enzymatic reaction steps but typical yields can be achieved of ca. 400 MBq. [C-11]-5-HTP is now reliably used in ongoing studies for staging NET. Copyright (c) 2006 John Wiley & Sons, Ltd.
|Number of pages||7|
|Journal||JOURNAL OF LABELLED COMPOUNDS & RADIOPHARMACEUTICALS|
|Publication status||Published - Sep-2006|