In vivo three-dimensional MR microscopy of mice with chronic relapsing experimental autoimmune encephalomyelitis after treatment with insulin-like growth factor-I.

PURPOSEThe purpose of this study was to determine the ability of three-dimensional in vivo MR microscopy to depict the treatment effects of insulin-like growth factor-I (IGF-I) in SJL mice with chronic relapsing experimental autoimmune encephalomyelitis (crEAE).METHODSThe experiments were performed at 4.7-T on 10 crEAE mice and on one set of control animals. Five crEAE mice were treated with IGF-I and five were treated with a placebo.RESULTSIn the crEAE mice treated with the placebo, in vivo MR microscopy showed areas of abnormal signal throughout the cerebrum, brain stem, and cerebellum. These findings were not present in either the IGF-I-treated mice or the normal control animals. The diffuse alterations in signal intensity in the placebo-treated crEAE mice were not identified on histologic sections of the same areas.CONCLUSIONDifferences between the IGF-I- and placebo-treated groups may reflect changes in stabilization or permeability of cell membranes and/or of the blood-brain barrier, although other alternative contrast mechanisms could be playing a role. In vivo MR microscopy depicted changes resulting from treatment of crEAE with IGF-I.