Fig. 2
In and ex vivo biodistribution of 18F-labeled Fe3O4@Al(OH)3 NPs or mMSCs labeled with these NPs. Mice were injected intravenously with saline, 18F-labeled Fe3O4@Al(OH)3 NPs (radiolabeled or RL NPs), or 100,000 mouse mesenchymal stem cells (mMSCs) labeled with RL NPs (mMSCs + RL NPs) while simultaneous PET/MRI images were acquired. a Representative maximum intensity projection (MIP) images and overlays of T2-weighted anatomical MR images and 18F-PET images (SUV = 0–9) show the uptake of 18F-labeled Fe3O4@Al(OH)3 NPs in the liver, while mMSCs labeled with RL NPs mainly accumulate in the lungs. In the latter group, signal from free NPs was also detected in the liver. Furthermore, uptake of 18F-labeled Fe3O4@Al(OH)3 NPs can be appreciated in the spleen of both groups, as indicated by the white arrows. b, c Corresponding quantification of b in vivo and c ex vivo standardized uptake values (SUV) of the liver, lungs, and spleen confirm the images. In vivo values represent the average SUV over the 1 h scan time. Indicated statistics are based on two-way ANOVA between the different groups with Bonferroni’s multiple comparisons test (*p < 0.05, ****p < 0.0001, ns, not significant)