Ferumoxytol-enhanced MRI may enable the assessment of altered immune cell activation and distribution in placental inflammation. In this work, quantitative susceptibility mapping (QSM) is proposed to assess the temporal variation of ferumoxytol concentration in the placenta. Three healthy pregnant rhesus monkeys were imaged at six time points relative to ferumoxytol injection. Longitudinal quantification of placental magnetic susceptibility and R1/R2/R2* relaxometry were performed to provide a preliminary assessment of the ferumoxytol variation in healthy rhesus placenta. This study demonstrated the feasibility of ferumoxytol-enhanced QSM and relaxometry in the rhesus placenta and may provide a method for the evaluation of placental inflammation.