Background: Interstitial laser coagulation (ILC) is a method of local tissue destruction for solid tumors such as irresectable hepatic metastases from colorectal cancer. With the availability of new magnetic resonance (MR) techniques, which allow real time tissue temperature mapping, it is essential to know the critical temperature and exposure times leading to cell death. Materials and Methods/ Study Design: Samples (8 mm 3 ) of solid rat tumor (CC-531, syngenic to the WAG/Rij rat strain), were warmed in tubes for four different temperatures (40, 50, 60 or 80ยฐC) and four different exposure times (3, 6, 12, or 24 minutes). Combinations were replicated in five-fold. Cell viability was assessed with three methods: Trypan blue exclusion test in collagenase/dispase dissociated samples, NADH activity in snap frozen samples and outgrowth for 2 weeks under the renal capsule of WAG/Rij rats. Results: Results of the three methods revealed that viability was not affected with heating at 40 and 50ยฐC except for 24 minutes at 50ยฐC. At higher temperatures cell death occurred at all exposure times.
Conclusion:
The temperature range resulting in sufficient tissue coagulation for cell death is between 50ยฐC and 60ยฐC for a short duration (<3 minutes). These data can be used to achieve complete tumor destruction and minimal surrounding tissue damage during real-time MR-controlled ILC.