Feasibility of Helical I-125 Seed Implant in the Portal Vein.

PURPOSE: To evaluate the feasibility of helical iodine-125 (I-125) seed portal vein implantation.

MATERIALS AND METHODS: Helical I-125 seed implants were placed into the portal vein of healthy pigs through the transjugular (n = 3) or percutaneous transhepatic (n = 3) route. Six pigs received follow-up at 9 weeks after implantation. Blood tests were performed preimplantation, and at 1 and 9 weeks after implantation. Contrast-enhanced computed tomography (CT) and single-photon emission computed tomography combined with CT (SPECT-CT) were acquired after implantation. Post-implantation CT was imported to the treatment planning system (TPS) for dose verification. At 9 weeks after implantation, another CT was performed before histopathological examination.

RESULTS: All implantations were successful, and the helical implants were fixed to the portal vein. CT showed no implant migration or portal vein thrombosis. The average dose to 90% of the target volume calculated from TPS was 68.4 Gy. SPECT-CT revealed an irregular isodose around the implant, in which the hottest spot was near the central portal vein lumen. All pigs were in good condition at the 9-week follow-up. Histopathology studies confirmed no portal vein thrombosis. Pigs showed no signs of bleeding, necrosis, or perforation of the peripheral tissue or organs. Intimal hyperplasia was observed at the two ends of the implant. A mild inflammatory response was detected in the bile duct and adjacent liver tissues, yet there was no apparent inflammation of the hepatic arteries.

CONCLUSION: The helical I-125 seed implants can be inserted into the portal veins of healthy pigs.