131I-labeled metaiodobenzylguanidine (MIBG) is an established treatment modality for neuroendocrine tumors. Because of low tumor doses, it has a predominantly palliative character. Our approach was to investigate whether intraarterial application of 131I-MIBG has the potential to enhance tumor uptake.
Methods: Seventeen patients with primary or metastasized neuroendocrine tumors received intraarterial treatment with 131I-MIBG, and 12 of these patients also had intravenous treatment. Every patient underwent intravenous 131I-MIBG whole-body scanning before therapy. For quantification, a tumor-to-whole-body ratio was calculated from the diagnostic and 24-h posttreatment scans.
Results: Compared with the intravenous application, intraarterial 131I-MIBG treatment provided an up to 4-fold higher tumor uptake. Mean uptake was enhanced by 69%, but this varied widely between patients. We did not observe any immediate complications from catheterization. Carcinoid-related side effects were noted in 7 of 17 patients and were not different from those seen with intravenous application.
Conclusion: Intraarterial treatment with 131I-MIBG is a safe alternative to intravenous application and provides a 69% higher mean tumor uptake. We propose to attempt intraarterial MIBG treatment in every patient to assess its potential benefit.