Laser brain surgery with near infrared lasers: Investigation of the optimal parameters by real-time temperature monitoring

The thermal damage of the surrounding tissue can be an unwanted result of continuous-wave laser irradiation. In order to propose an effective way alternative to conventional surgical techniques, photothermal damage must be taken under control by a detailed dose study. Real-time temperature monitoring can be also an effective way to get rid of these side effects. The aim of this study was to overcome the side effects of photothermal interactions with a better establishment of experiments for investigating the photothermal effects of lasers and to specify optimal laser parameters in order to propose lasers in clinical use. In the present study, ablation/vaporization capability of three different infrared lasers operating at 980-nm, 1070-nm and 1940-nm were investigated through comparative experiments. All studies were performed ex vivo followed by in vivo with real-time temperature monitoring and male Wistar rats were used as an animal model. Animals were sacrificed immediately after the stereotaxic surgery for histological examinations. Sections were stained with Cresyl Fast Violet in order to measure the thermally altered areas. The relation between laser parameters, temperature changes and ablation efficiency were determined. The correlations between rate of temperature change and ablation efficiency were calculated. In conclusion, this comparative study showed that the change in temperature in the tissue during laser irradiation, even though the laser source is different in terms of wavelength, can be a good indicator for the characteristics of lesion created by the laser.