INTERNALLY COOLED POWER LASER FOR MR-GUIDED INTERSTITIAL LASER-INDUCED THERMOTHERAPY OF LIVER-LESIONS - INITIAL CLINICAL-RESULTS

PURPOSE: To evaluate experimentally and clinically an internally coole d power laser system for percutaneous treatment of liver metastases, w ith magnetic resonance (MR) imaging guidance, to increase the volume o f coagulative necrosis with single laser beam applications. MATERIALS AND METHODS: The power laser system consisted of standard cannulation paraphernalia and a specially designed 7-F protective catheter for coo ling the laser tip during treatment to avoid carbonization. A microdom e laser beam applicator with a laser tip diameter of 0.95 mm kept the entire device as small as possible. After the unit was tested in 40 po rcine livers, 532 laser beam applications (mean power, 27.5 W [range, 22.1-30.0 W]; mean application time, 19.8 minutes [range, 14-30 minute s]) were performed with MR guidance in 127 patients with 318 liver met astases. The safety of the procedure and the volume of induced necrosi s were evaluated. RESULTS: In vitro, cuboid areas of coagulative necro sis with a mean greatest diameter of 4.3 cm +/- 0.5 (SD) were demonstr ated after single applications. In vivo, MR thermometry allowed accura te demarcation of changes induced by heat, with a mean diameter of nec rosis of 3.3 cm +/- 1.4. No carbonization or vaporization of tissue or damage of equipment occurred during treatment. CONCLUSION: This power laser system can increase the volume of laser-induced necrosis in liv er metastases with a single application, thereby simplifying and accel erating the treatment of larger lesions.