Abstract #0468

Madar N, Brami C, Neeman M, Salomon Y, Scherz A, Kalchenko V

Vascular Targeting Photodynamic therapy (VTP) relies on local photogeneration of a circulating photosensitizer and generation of cytotoxic reactive oxygen species leading to tumor eradication. To further understand the mechanistic basis of photosensitized MRI, the vascular response during VTP was examined online on the mouse ear model by IntraVital microscopy and fMRI. Increased tumor BOLD contrast during VTP was correlated with decrease in blood flow velocity, and contained two phases, one early (tVTP<5min) light-dependent and reversible, followed by a light-independent late phase (5min>tVTP>10min); characterized by irreversible high BOLD contrast. Supported by STEBA BIOTECH & NEGMA LERADS, France