IODIZED OIL ENHANCES THE THERMAL EFFECT OF HIGH-INTENSITY FOCUSED ULTRASOUND ON ABLATING EXPERIMENTAL LIVER-CANCER

The influence of the biological medium on high-intensity focused ultra sound (HIFU) therapy for ablating experimental liver cancer was studie d. In study 1, the temperature rise in the focal zone in the presence of iodized oil or castor oil was observed in vitro. The results showed that HIFU with iodized oil produced a higher and faster temperature r ise than did HIFU with castor oil, whether high-power (500 W/cm(2)) or relatively low-power (136 W/cm(2)) conditions were used (P=0.0008 and P=0.0004 respectively). With the excised liver samples, the temperatu re also rose higher and more rapidly after injection of iodized oil in to the liver than when castor oil was injected (P=0.0239), and the tar get liver tissue revealed more radically and extensive destruction wit h iodized oil than with castor oil. In study 2, 48 nude mice, bearing primary liver cancer LTNM4 implanted subcutaneously, were randomly div ided into four groups. Group I (n = 12) were the controls, group II (n =12) were injected with iodized oil alone, group III (n = 12) received HIFU treatement, and group IV (n = 12) were exposed to HIFU after iod ized oil injection. Significant inhibition of tumor growth was seen in groups III and IV as compared with group I or group II (P < 0.05), th e tumor growth inhibition rate on the 28th day after treatment being 8 7% and 93% respectively. Significantly improved survival was noted in groups III and IV compared with groups I and II (P < 0.05). Histologic ally, group IV showed more complete tumor necrosis than did group III. These data suggest that HIFU combined with iodized oil might have ach ieve of synergism, location and targeting in the treatment of liver ca ncer.