Early clinical experience with pre-operative MR-guided laser-induced thermotherapy (LITT) of liver metastases

Purpose: To evaluate the LITT-induced changes with the aid of MRT and correlate these with histopathological findings. Material and methods: Five patients with solitary cole rectal liver metastases were treated by means of MR-guided LITT before liver resection. Application time and energy of the Nd:YAG laser (1064 nm) was 10-20 minutes and 4.5-8.8 W. MRT monitoring during the LITT was carried out with temperature-sensitive T-1 weighted sequences (FLASH-2-D, turbo FLASH). The extent of the induced necrosis as seen on MR was compared with the unfixed specimen and with the histopathological findings. Results: The extent of necrosis visible by MRT correlated with the histopathological findings with an accuracy of 95.3%+/-4.2 %. Following single treatments (three cases) the metastases suffered a reduction of 24%-55 % of their original volume. In two patients a second application produced laser-induced necrosis of 78 % and 98 % of volume. In these two patients a temperature sound was used for measuring regional healing and showed an exact correlation with MR thermometry. Conclusion: The results of pre-operative MR-guided LITT indicates the potential of this form of treatment for obtaining reproducible tumor necrosis of liver metastases.