Abstract
In this study we report the tumor responses to photodynamic therapy (PDT) as measured by in vivo 31P NMR and water relaxation measurements on a murine tumor model. We evaluate the PDT responses to two new photosensitizers by monitoring the tumor volumes post PDT for one tumor and by in vivo 31P NMR for the other. Both photosensitizers are structurally well defined, pure compounds, unlike Photofrin II (PF II), which is a complex chemical mixture of a variety of porphyrin species. Dramatic increases in inorganic phosphate (Pi) were noticed following PDT treatment. The tumor water relaxation time measurements also suggest corresponding increases in Tl values of water after PDT treatment. From a combined study of relaxation times, 31P NMR, and tumor volumes, we conclude that the relaxation measurements can serve as a useful and sensitive method of monitoring PDT.
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