Macromoleular contrast agents in MRI have been used widely in pre-clinical studies. They have been very effective in determining two hemodynamic parameters that correlate strongly with tumor grade: tumor blood volume and tumor permeability ^1. Thus, determining either of these parameters may be a useful indicator for tumor prognosis ^1-3 and tumor response to therapy ^4-6. We pose the following question: Can optical imaging of accessible tumors, i.e., in studies of subcutaneous tumors, be used in a way as to evaluate either of these parameters? We present preliminary data that suggest that a simple experimental protocol can provide at least an index of the permeability parameter if not the absolute permeability itself.