Figure 6.

Lymph node PET/MRI imaging of a mouse with inflamed right leg using ¹⁸F-labeled Fe₃O₄@NaYF₄(Yb, Tm)-BP-PEG NPs (a–d) or with [¹⁸F]-fluoride only (e–g): (a) whole body PET image showing uptake of radiolabeled NPs (maximum intensity projection; bone uptake was observed due to gradual release of fluoride from NPs due to the 7 h delay post injection of NPs); (b) PET image showing popliteal and iliac lymph nodes (coronal section); (c) PET/MRI fused image (coronal section); (d) MR image (coronal section) with darkening contrast inside popliteal lymph node at left-rear (white circle) and “outside” lymph node at the inflamed right-rear (red circle) induced by injection of 30 μL 0.67 mg/mL lipopolyscchrade (LPS) 18 h prior to imaging, and at iliac lymph node; (e) PET image following injection of [¹⁸F]-fluoride showing no contrast in lymph nodes in the absence of NPs and prominent uptake by skeleton; (f) PET/MRI fused image following injection of [¹⁸F]-fluoride, showing no radioactivity associated with lymph nodes; (g) MR image showing no difference between normal popliteal lymph node at left-rear leg (white circle) and the inflamed lymph node at right-rear leg induced by injection of 30 μL 0.67 mg/mL LPS 18 h prior to imaging; and (h–k) enlarged MR images of corresponding lymph nodes.