Figure 5.

PET/MRI images of a normal young C57BL/6 mouse showing LNs with dual contrast provided by ¹⁸F-labeled Co_0.16Fe_2.84O₄@NaYF₄(Yb, Er)-BP-PEG: (a) schematic diagram showing the connections between lymph nodes and the injection point (mouse in supine position); (b) whole body PET image showing uptake of radiolabeled NPs 7 h post injection (maximum intensity projection, mice in prone position); (c) MR image with darkening contrast at popliteal LN (coronal section); (d) PET image showing radioactivity at popliteal, inguinal, lumbar aortic, and aorta LN area (coronal section); and (e) PET/MRI fused image showing popliteal, inguinal, lumbar aortic, and aorta LN (coronal section). Some bone uptake of radioactivity is observed in (b), (d), and (e) due to gradual release of fluoride from the particles due to the long delay (7 h post injection of ¹⁸F radiolabeled NPs) between injection and imaging.