Combined use is made of image values at corresponding image locations defined by amide proton transfer MRI image data and 18F-FLT, 11C-MET, or 18F-FDG PET image data. The combined use may include computing multimodal heterogeneity for combined PET and amide proton transfer MRI image values, using PET image data to distinguish different image locations during processing and/or display of amide proton transfer image data, and tissue classification based on combinations of values derived from the amide proton transfer MRI and/or PET images.
