OPTICAL-PROPERTIES OF NATIVE AND COAGULATED HUMAN LIVER-TISSUE AND LIVER METASTASES IN THE NEAR-INFRARED RANGE

Background and Objective: Knowledge about optical parameters and the r esultant light distribution in laser-treated tissue is important for p redicting the effects of laser-induced thermotherapy of liver metastas es (LITT). Materials and Methods: The absorption and scattering coeffi cients as well as the anisotropy factors and the optical penetration d epths of human liver tissue and colorectal liver metastases were deter mined at 850, 980, and 1,064 nm under native and thermocoagulated cond itions. Results: Liver metastases had a lower anisotropy factor, absor ption, and scattering coefficient than healthy liver (P < 0.01), resul ting in a significantly higher optical penetration depth in metastatic tissue. Coagulation significantly changes the optical parameters by r educing the optical penetration depth in both tissue types (P < 0.01). Conclusions: A greater optical penetration depth in metastatic tissue is advantageous for LITT, since larger tumor volumes can be coagulate d. At the same time, an adjustment of the application parameters durin g LITT is necessary to achieve optimal therapeutic success. (C) 1998 W iley-Liss, Inc.