[Preparation of 131I-VIP and 131I-VIP receptor imaging]

This study was aimed at the preparation of 131I-vasoactive intestinal peptide (VIP) and its preliminary application in clinical imaging. VIP was labeled with Na 131I using chloramine-T method, then isolated by Sephadex G-10 column chromatography and examined by silica 60F254 thin layer chromatography. The bacteria and pyrogen were examined and the safety test was carried out. One control and two patients suffering from abdomen tumor were investigated. The results showed that the labeling rate of 131I was 80% and the specific activity of 131I-VIP was 36 TBq/mmol. The radiochemical purity of 131I-VIP was over 98%, and it decreased to 95% after six hours' storage at 4 degrees C. It was proved that the 131I-VIP eluate had no bacteria, no pyrogen and no poison. The injected 131I-VIP was distributed into the lungs immediately and was eliminated through kidneys. The primary tumor could be visualized about half an hour to 3 hours after injection. This study demonstrates that 131I-VIP is suitable for in vivo imaging and may be used as an effective tracer to identify the tumor site in patients with VIP receptor positive carcinoma.