Study of mechanical and thermal damage in brain tissue after ablation by Erbium-YAG laser

This work studied the ablation of bovine brain tissue by free-running Erbium-YAG laser pulses. Single-shot interactions were investigated by means of an ultra-fast imaging technique. Thin sections of the treated tissue were processed for histochemical analysis of enzyme activity to assess the extent of thermal/mechanical damage. Thereafter, a scanning beam technique was employed to deliver multiple pulses over a definite region of tissue. An analytical balance was used to measure the removed mass in order to calculate the ablation efficiency. The present quantity has been compared to the amount of the tissue damaged, as assessed by the histochemical analysis. The present work shows that the interaction of the Erbium-YAG laser pulses with a soft tissue may cause a large amount of mechanical damage, while thermal damage is restricted within a thin layer around the ablation crater. A precise control of fluence and operating conditions prevents overwhelming side-effects, and possibly allows the use of the Erbium-YAG laser for the ablation of brain and other soft tissues.