Purpose: Accurate N-staging is essential for managing prostate cancer, but current methods often miss small-volume nodal disease. Ferumoxtran-10-enhanced MRI (macrophage (m)-MRI) provides better sensitivity and specificity but lacks standardized protocols, which limits its use. We introduce Fe-RADS-PR (Prostate), a standardized system for acquisition and reporting aimed at improving m-MRI for nodal staging. Methods: The five-category Fe-RADS-PR Likert system was developed through a rigorous two-step process. First, it synthesized expert consensus based on extensive clinical experience with approximately 2,750 cases. Second, preoperative m-MRI was performed in 17 patients with prostate cancer, followed by extended pelvic lymph node dissection (ePLND). Afterwards, we performed meticulous node-by-node correlation of in-vivo m-MRI features with high-resolution ex-vivo specimen on 7T MRI and gold standard histopathology to define distinctive intranodal patterns. Results: The validation cohort consisted of 327 lymph nodes, with 41 metastatic and 286 benign. The thorough histo-radiological correlation established the 5-point Fe-RADS-PR score regarding the presence of lymph node metastases (LNM): (1) LNM Highly Unlikely, (2) LNM Unlikely, (3) Equivocal, (4) LNM Likely, and (5) LNM Highly Likely. Importantly, this score reflects both the probability and extent of intranodal metastatic infiltration, surpassing simple morphological criteria. Limitations: The system needs prospective multicenter validation before it can be widely adopted clinically, as the current validation cohort is limited. Conclusions: Fe-RADS-PR provides a robust and standardized approach for the acquisition and interpretation of m-MRI. Similar to PI-RADS for the primary tumor, Fe-RADS-PR aims to improve diagnostic accuracy, enhance inter-reader agreement, and streamline clinical decision-making in prostate cancer nodal staging.