Biodistribution of labeled ASCs in a rat injected via tail vein. Maximum intensity projection of whole-body PET image (a) of a rat injected with double-labeled ASCs via tail vein (25 μg/ml SPIO and 2.3 MBq FDG). The image is reconstructed with MAP algorithm and attenuation corrected. The panel on the right (b) represents the image with the heart at the center of field of view. The arrow heads point out to the lungs (solid) and the heart (dashed). It is evident that the majority of the cells are retained in the lungs and the heart is not visible.