Recent years have seen a tremendous explosion in both the number and quantity of imaging techniques that can be applied in the quantitative characterization of cancer. These techniques have come from all fields of non-invasive, in vivo medical imaging including magnetic resonance imaging (MRI), optical imaging, computed tomography (CT), positron emission tomography (PET), single photon emission computed tomography (SPECT), and ultrasound. Relevant techniques that have been developed report on, for example, tumor cellularity, vessel perfusion and permeability, hypoxic fractions, as well as cellular and molecular signatures. It is a reasonable hypothesis that characterization of tissue status can offer increased sensitivity and specificity when diagnosing and grading tumors. Furthermore, as many current anti-cancer drugs are designed to alter these specific tumor characteristics, imaging metrics designed to report on those phenomena promise to offer improved methods of planning treatment as well as assessing the response of tumors to treatment--Provided by publisher.