Abstract: A method of estimating the true uptake of a tracer in a physiological image acquired with a physiological image modality that has limited spatial resolution comprises: co-registering an anatomical image volume and the physiological image volume such that both image volumes have corresponding voxels; segmenting the anatomical image volume into a number of non-overlapping anatomical regions; combining each of the segmented anatomical regions with a function representative of the limited spatial resolution of the physiological image modality to generate a blurred anatomical region volume for each of the segmented regions; assuming the physiological image in each voxel to be a linear sum of the image intensities of the corresponding voxels in the blurred region volumes in that voxel; estimating, for each voxel, a value representative of the contribution to that voxel from each blurred region volume based on the uptake measured by the physiological image for that voxel and for nearby voxels; and using the estimate