AIM We tried to develop a multimodal iron oxide nanoparticles (IO NP) imaging probe by an encapsulation method using specific amphiphiles for (68)Ga-labeling and lymph node-targeting. MATERIALS & METHODS Nanoparticles (NPs) were encapsulated with a solution containing polysorbate 60 and the amphiphiles. The prepared NPs were labeled with (68)Ga and tested in vitro and in vivo. RESULTS Prepared 1,4,7-triazacyclononane-1,4,7-triacetic acid-IO-Mannose (NOTA-IO-Man) showed a narrow size distribution, and no significant aggregation or degradation under harsh conditions. The relaxivity coefficient of (68)Ga-NOTA-IO-Man was higher than that of ferumoxide. The accumulation of (68)Ga-NOTA-IO-Man in the lymph node after injection into rat's footpad was confirmed by both positron emission tomography and MRI. CONCLUSION We successfully developed PET/MRI dual-modality imaging probe targeting lymph nodes by using the facile encapsulation method.