Broadband reflectance measurements of light penetration, blood oxygenation, hemoglobin concentration, and drug concentration in human intraperitoneal tissues before and after photodynamic therapy

We evaluate Photofrin-mediated photodynamic therapy (PDT) in a phase 2 clinical trial as an adjuvant to surgery to treat peritoneal carcinomatosis. We extract tissue optical [reduced scattering (mu'(s)), absorption (mu'(a)), and attenuation coefficients (mu(eff))] and physiological [blood oxygen saturation (%StO2), total hemoglobin concentration (THC), and photosensitizer concentration (C-Photofrin)] properties in 12 patients using a diffuse reflectance instrument and algorithms based on the diffusion equation. Before PDT, in normal intraperitoneal tissues %StO2 and THC ranged between 32 to 100% and 19 to 263 AM, respectively; corresponding data from tumor tissues ranged between 11 to 44% and 61 to 224 mu M. Tumor %StO2 is significantly lower than oxygenation of normal intraperitoneal tissues in the same patients. The mean (:standard error of mean) penetration depth (delta) in millimeters at 630 nm is 4.8(+/- 0.6) for small bowel, 5.2 (+/- 0.67) for large bowel, 3.39(+/- 0.29) for peritoneum, 5.19(+/- 1.4) for skin, 1.0(+/- 0.1) for liver, and 3.02(+/- 0.66) for tumor. C-Photofrin in micromolars is 4.9(+/- 2.3) for small bowel, 4.8(+/- 2.3) for large bowel, 3.0 (+/- 1.0) for peritoneum, 2.5(+/- 0.9) for skin, and 7.4(+/- 2.8) for tumor. In all tissues examined, mean C-Photofrin tends to decrease after PDT, perhaps due to photobleaching. These results provide benchmark in-vivo tissue optical property data, and demonstrate the feasibility of in-situ measurements during clinical PDT treatments. (c) 2005 Society of Photo-Optical Instrumentation Engineers.