RESPONSES TO PHOTODYNAMIC THERAPY IN A MURINE TUMOR-MODEL - P-31 NMR AND WATER PROTON RELAXATION STUDIES

In this study we report the tumor responses to photodynamic therapy (P DT) as measured by in vivo P-31 NMR and water relaxation measurements on a murine tumor model. We evaluate the POT responses to two new phot osensitizers by monitoring the tumor volumes post PDT forone tumor and by in vivo P-31 NMR for the other. Both photosensitizers are structur ally well defined, pure compounds, unlike Photofrin II (PF II), which is a complex chemical mixture of a variety of porphyrin species. Drama tic increases in inorganic phosphate (P-1) wereollowing PDT treatment. The tumor water relaxation time measurements also suggest correspondi ng increases in T-1 values after PDT treatment. From a combined study of relaxation times, P-31 NMR, and tumor volumes, we conclude that the relaxation measurements can serve as a useful and sensitive method of monitoring PDT.