Biodistribution and in vivo kinetics of iodine-131 lipiodol infused via the hepatic artery of patients with hepatic cancer.

The biodistribution and in vivo kinetics of [131I]lipiodol infused into the hepatic artery were studied to estimate the potential of internal radiotherapy of hepatic cancer in five patients. It accumulated only in the vascular tumors and adjacent hepatic tissue (AHT) supplied by the infused artery, and to a lesser extent in the lung throughout 8 days imaging sequence. Iodine-131 lipiodol appeared to lead to oil embolization of the tumor and AHT followed by secondary embolization to the lungs and finally the activity was mainly excreted into urine. Four tumors had rapidly and slowly decreasing components, while the AHT activity decreased exponentially from the beginning. The effective half life in tumors was longer with the slow component (mean +/- s.d.: 5.7 +/- 1.2 days) than the AHT (3.7 +/- 0.6 days). The tumor/AHT concentration ratio in three patients at 2 hr was estimated to be 7.5-21. The activity was lower in the lungs than in the AHT in four patients. Iodine-131 lipiodol thus may be used as an intra-arterial infusion agent to treat certain vascular hepatic cancers.