Quantitative comparison of tissue oxygen and motexafin lutetium uptake by ex vivo and noninvasive in vivo techniques in patients with intraperitoneal carcinomatosis

Near-infrared diffuse reflectance spectroscopy DRS has been used to noninvasively monitor optical properties during photo- dynamic therapy PDT. This technique has been extensively vali- dated in tissue phantoms; however, validation in patients has been limited. This pilot study compares blood oxygenation and photosen- sitizer tissue uptake measured by multiwavelength DRS with ex vivo assays of the hypoxia marker, 2-2-nitroimida-zol-1H-yl-N- 2,2,3,3,3-pentafluoropropylacetamide EF5, and the photosensitizer motexafin lutetium, MLu from tissues at the same tumor site of three tumors in two patients with intra-abdominal cancers. Similar in vivo and ex vivo measurements of MLu concentration are carried out in murine radiation-induced fibrosarcoma RIF tumors n=9. The se- lection of optimal DRS wavelength range and source-detector separa- tions is discussed and implemented, and the association between in vivo and ex vivo measurements is examined. The results demon- strate a negative correlation between blood oxygen saturation StO2 and EF5 binding, consistent with published relationships between EF5 binding and electrode measured pO2, and between electrode mea- sured pO2 and StO2. A tight correspondence is observed between in vivo DRS and ex vivo measured MLu concentration in the RIF tumors; similar data are positively correlated in the human intraperitoneal tu- mors. These results further demonstrate the potential of in vivo DRS measurements in clinical PDT. © 2007 Society of Photo-Optical Instrumentation