Nd-YAG laser thermal effect: Comparative study of coagulation in rat liver in vivo by continuous wave and high power pulsed lasers

Abstract: The coagulation effect of a continuous-wave neodymium-YAG (Nd-YAG) laser and of a high-power (500 W) pulsed (3–500 ms) microcomputer-controlled Nd-YAG laser are compared in rat liver in vivo. In a series of 68 animals, surface temperature was measured with an infrared camera, and necrosed volume was assessed histologically 24 h after laser irradiation. The high-power pulsed Nd-YAG laser presents two interesting features. First, it gives a better control of surface temperature. Second, a controlled sequence of high-power short pulses produces a predictable coagulated volume which can be comparable to that obtained with continuous-wave Nd-YAG or argon lasers.