Laser-induced interstitial thermotherapy of liver metastases in an interventional 0.5 tesla MRI system: Technique and first clinical experiences

Laser-induced interstitial thermotherapy (LITT) surveyed by magnetic resona nce Imaging (MRI) has been shown to be effective In various applications. T he laser treatment of colorectal liver metastases usually requires a separa te device (e.g., ultrasound or CT) to position the laser applicator. In thi s study, we used an interventional 0.5 T MM system, allowing both the navig ation to the target tissue and on-fine thermometry. Laser irradiation was p erformed using a near-infrared laser source combined with a cooled laser li ght guide. We treated 20 patients exhibiting a total of 58 colorectal liver metastases. Clinically relevant complications did not occur. No residual t umor was observed after laser Irradiation In all metastases with a diameter below 2 cm. Metastases with a mean diameter between 2 and 3 cm demonstrate d total necrosis In 71%, while in larger tumors this proportion decreased t o 46% (diameter, 3-4 cm) and 30% (diameter, >4 cm), respectively. We conclu de that LITT, guided by the employed Interventional MRI system, Is feasible and safe. The results suggest a more aggressive treatment, especially for larger metastases. (C) 2001 Wiley-Liss, Inc.