Olivier M. Girard1, Rose Ramirez1, Stephanie McCarty1,2, Elamprakash N. Savariar3, Robert F. Mattrey1
1Department of Radiology, University of California, San Diego, CA, United States; 2New York Medical College, Valhalla, NY, United States; 3Department of Pharmacology, University of California, San Diego, CA, United States
Iron oxide nanoparticles (IONPs) are widely used in cellular MRI because of their strong magnetic properties. However quantification of absolute concentration still remains a challenge because relaxivities depend on IONP distribution within a given sample. Recent works on susceptibility mapping have suggested that susceptibility measurements could be used for IONP quantification. Here we study IONP samples that contain a mixture of free- and cell-internalized- IONPs. We investigate multiple MR characteristic parameters (T1, T2, T2* and χ) in order to extract absolute IONP concentration as well as free vs. internalized IONP fractions.