MR imaging of inflammation during myelin-specific T cell-mediated autoimmune attack in the EAE mouse spinal cord

Purpose: The purpose of this study is to detect myelin-specific T cells, key pathological mediators in early multiple sclerosis, and the corresponding animal model, experimental autoimmune encephalomyelitis (EAE), in the mouse spinal cord. Procedures: T cells were labeled with the iron-based, magnetic resonance (MR) contrast reagent, Feridex, and the transfection reagent, protamine sulfate, resulting in ∼100% iron-labeling efficiency. Feridex-labeling did not alter the induction of EAE by T cells, and recipients were imaged by a 12-T MR instrument. Results: Focal hypointense lesions were resolvable to gray or white matter of the lumbar spinal cord in T2-weighted images of the recipients of Feridex-labeled T cells. Lesions corresponded to histological evidence of inflammatory lesions and iron-labeled cells in eight-of-eight mice. In contrast, hypointense lesions were not observed eight-of-eight recipients of unlabeled T cells. Conclusions: These results demonstrate and provide methodologies for labeling, detecting, and extracting MRI-detectable foci of iron-labeled cells.