The specificity and efficacy of Mann2-DPTA-Gd were further validated in experimental glioma, in which Mann2-DTPA-Gd imaging detected CD206+ tumor-associated macrophages (TAMs), demonstrated significantly decreased signals in Mrc1+/- mice and Mrc1-/- mice, and tracked treatment changes in D-mannose-treated Mrc1+/+ mice. Here, MRC1 is linked to central nervous system cancer.