Kinetics of Photofrin II in perifocal brain edema.

Photodynamic therapy is under intense investigation as a possible adjuvant for the treatment of malignant tumors of the central nervous system. It relies on the fact that photosensitizers are selectively taken up or retained by malignant tissue. However, most brain tumors are accompanied by substantial vasogenic edema as a consequence of blood-brain barrier disruption within the tumor, leading to extravasation and propagation of plasma constituents into the surrounding brain tissue. Systemically administered photosensitizers may enter healthy tissue together with the edema fluid, possibly leading to sensitization of tissues outside the tumor. To test this hypothesis, vasogenic edema was ind…