MRI characterization of iron in soluble (ferritin-like) and particulate (hemosiderin-like) mixtures

particulate mixture phantoms using a modified multi-echo CPMG sequence at 7 Tesla. Top: MRI estimation of the concentrations of mouse embryonic stem cells (ESCs) (top left) and human embryonic kidney cells (HEKs) (top right) suspended in agarose gel. The cells were intracellularly loaded with aggregated iron oxide particles (nanometer-sized MION particles for ESCs with 2-4 pg Fe/cell and 0.9 μm MPIO particles for HEKs with 3-10 pg/cell). Bottom left: MRI estimation of soluble nanometer-sized iron (MION, “ferritin”) in varying concentrations with fixed concentration of micron-sized iron oxide particle concentration (4.5μm MPIO, 5x10 beads/mL, “hemosiderin”) in agarose gel phantoms. Bottom Right: Typical multi-echo CPMG signal decays with theoretical fittings from a phantom that contains micron-sized iron particles or chunks. Note these CPMG signal decays are non-exponential and have a strong dependence on the interecho time 2∆t. REFERENCES 1.Brittenham GM et al. Blood 2003;101(1):15. 2.Ghugre NR et al. MRM 2005;54(5):1185. 3.Jensen PD. Br J Haematol 2004;124(6):697. 4.Gossuin Y et al. MRM 2000;43(2):237. 5.Jensen JH et al. MRM 2002;47(6):1131. 6.Sheth S et al. Ann N Y Acad Sci 2005;1054:358. MRI Characterization of Iron in Soluble (Ferritin-like) and Particulate (Hemosiderin-like) Mixtures