Rousseau, J.; Wang, T.-Y.; Wu, S.-P.; Beeman, S. C.; Wang, K.-C.

Noninvasive monitoring of plaque inflammatory dynamics remains an unmet need. We previously developed a monocyte-mimetic nanoprobe, termed MoNP-SPION, for MRI detection of atherosclerotic lesions. Here we demonstrate MoNP-SPION enables longitudinal tracking of plaque inflammatory status in a clinically relevant mouse model. Following 16 weeks of plaque induction, mice were maintained on high-fat diet or switched to chow for 6 weeks to model persistent versus resolving plaque inflammation. MoNP-SPION-enhanced MRI was performed at 3- and 6-weeks post-adjustment, and arterial tissue was collected for histological assessment. Mice maintained on high-fat diet exhibited persistent hypointense T2* signal at the carotid bifurcation and aortic root, whereas chow-transitioned mice showed progressive signal attenuation, consistent with histological evidence of reduced plaque burden and inflammation. These findings establish MoNP-SPION as an effective molecular MRI probe for longitudinal assessment of plaque inflammatory dynamics, supporting its potential for monitoring atherosclerosis progression and therapeutic response.