Intra-arterial administration of sodium borocaptate (BSH)/lipiodol emulsion delivers B-10 to liver tumors highly selectively for boron neutron capture therapy: Experimental studies in the rat liver model

Purpose: Boron neutron capture therapy (BNCT) is particle radiotherapy with alpha (He-4) particle and recoiled lithium nucleus (Li-7) derived from a reaction of boron (B-10) and thermal neutron. We investigated applying BNCT to malignant liver tumors. The purpose of the present study was to reveal the efficacy for administration of emulsion of a boron compound (sodium borocaptate; BSH) and lipiodol via a hepatic artery using a rat liver tumor model. Methods and Materials: Rat liver tumors were developed by direct injection of Walker 256 cells into the liver parenchyma. BSH (75 mg/kg)/lipiodol (0.3 mL/kg) emulsion was administered via the hepatic artery. Boron concentrations in the tumors, liver, and blood were measured at 1, 6, and 12 h after administration. Neutron capture radiography (NCR) was taken to confirm the selective accumulation of B-10 in the liver tumors. Results Boron concentrations in the liver tumors and the tumor/liver (T/L) boron concentration ratio at 1, 6, and 12 h after administration of BSH/lipiodol emulsion (concentration: T/L ratio) were 479.2 ppm: 4.0, 197.3 ppm: 14.9, and 96.5 ppm: 6.6, respectively. Highly selective irradiation was clearly demonstrated by the NCR images. Conclusions: Intra-arterial administration of BSH/lipiodol emulsion is effective method for delivering high concentration of B-10 selectively to the liver tumors. (C) 2004 Elsevier Inc.