bookmark SFSRR Recovers accurate quantitative radioactivity concentration in Positron Emission Tomography (PET) images. SFSRR combines functional and structural information from a number of sources such as computerized tomography (CT), Magnetic Resonance Imaging (MRI) and anatomical probabilistic atlases. It is based on the multiresolution property of the wavelet transform. It is able to incorporate standardized anatomical information. The tool was validated on a digital Zubal phantom and clinical data to evaluate its quantitative potential.