Near-infrared optical properties of ex vivo human uterus determined by the Monte Carlo inversion technique.

The optical properties, absorption (mua) and reduced scattering coefficient (mu's), of ex vivo human myometrium and leiomyoma (fibroid) have been determined by the Monte Carlo inversion technique over the wavelength range 600-1000 nm. This region is currently of interest for new, minimal-access, surgical laser procedures such as photodynamic therapy (PDT) for abnormalities of the uterus, and interstitial laser photocoagulation (ILP) for the thermal ablation of fibroids. In the region 630-675 nm (corresponding to PDT), the optical coefficients of myometrium are mua = 0.041+/-0.012 mm(-1) and mu's = 1.37+/-0.19 mm(-1). For the wavelength range 800-1000 nm (associated with infrared lasers for ILP), the optical coefficients of fibroid were found to be mua = 0.020+/-0.003 mm(-1) and mu's = 0.56+/-0.03 mm(-1). Overall, the optical properties of fibroid were found to be lower than myometrium, and this was attributed to the differences in both anatomy and vascularity. The results show that PDT for ablation of the uterine endometrium is most unlikely to affect any tissues beyond the myometrium, and that the region around 800 nm is the most effective for ablation of fibroids using ILP as the penetration depth of light is greatest at this wavelength.