Optical properties of native and coagulated porcine liver tissue between 400 and 2400 nm

Background and Objective: Laser induced thermotherapy (LITT) is a promising treatment for irresectable liver tumors. For predicting the effects of las er applications and optimizing irradiation planning in LITT, knowledge abou t light distribution in tissue, optical tissue properties (absorption, scat tering, anisotropy, penetration depth) and their changes due to thermal den aturation is indispensable. Study Design/Materials and Methods: The optical parameters in healthy porci ne liver were determined in the native state and after thermal coagulation using a double integrating sphere system in the wavelength range of 400-240 0 nm. Results: Optical parameters showed significant fluctuations in the examined wavelength range mainly due to the water and hemoglobin content in the tis sue. The greatest optical penetration depth of 7.46 mm was achieved at 1070 nm. After thermal coagulation, a clear increase in scattering and a slight decrease in absorption was found, which results in a decreased optical pen etration depth. Conclusion: In order to ensure a safe and effective procedure, an adjustmen t of the laser power to the decreasing penetration depth is recommended dur ing therapy. These results provide a better understanding of laser-tissue i nteraction and may be helpful to investigators in the field of light dosime try in liver tissue. (C) 2001 Wiley-Liss, Inc.