Liver tissue damage by ultrasound in combination with the photosensitizing drug, Photofrin II.

We have investigated whether ablation of normal rat liver by ultrasound can be enhanced after administration of a photosensitizing agent (Photofrin II). After laparotomy and administration of Photofrin II (30 mg/kg), ultrasound (210 kHz, 1.3 W/cm2) was directed directly to the surface of the liver for a total duration of 3 min by a plane type unfocused transducer (6 mm x 6 mm). The depth of tissue damage was histologically compared to rats exposed to ultrasound alone. The mean maximum lesion depth on rats applied with ultrasound and Photofrin II was 5.7 +/- 0.9 mm (mean +/- SD) whereas in rats treated with ultrasound alone this was 3.0 +/- 0.4 mm. There was a significant difference between the two groups (P < 0.05). The present study suggests the possible use of a photosensitizing agent as an enhancer for the treatment of liver tumors by ultrasound.