Interstitial laser thermotherapy of a rat liver tumour: effect of hepatic inflow occlusion.

Background and Objective: Interstitial laser thermotherapy was used to treat rat liver tumours. The aim was to investigate the influence of temperature and temporary hepatic inflow occlusion on tumour growth and blood perfusion. Study Design/Materials and Methods: Liver tumours were treated at 44 degrees C at the tumour border for 30 minutes, hepatic inflow occlusion only, or a combination of these methods. Interstitial laser Doppler flowmetry was used to measure hepatic perfusion at the tumour border during and after heat treatment, for a total time of 60 minutes. Tumour growth was evaluated 6 days after treatment. Results: Tumours subjected to the combined treatment of hepatic inflow occlusion and interstitial laser thermotherapy displayed a blood perfusion reduction 30 minutes after treatment to 18 +/- 5% of initial perfusion, which was significantly lower than achieved with thermotherapy alone (52 +/- 10%, P = 0.02). The combined treatment and treatment with thermotherapy alone resulted in relative tumour growth of 0.3 +/- 0.1 and 1.0 +/- 0.2, respectively (P = 0.04). Conclusion: Inflow occlusion enhanced the effect of thermotherapy not by augmenting treatment temperatures but by increasing the thermal sensitivity of the tumour, reflected by an immediate effect on tumour blood perfusion. Lasers Surg. Med. 43:29-35, 2011. (C) 2011 Wiley-Liss, Inc.