[Manganese enhanced magnetic resonance imaging for tracing corticospinal tracts in rat brain using 7.0 T MRI].

OBJECTIVE: To investigate the methods of manganese enhanced magnetic resonance imaging in 7.0 T magnetic field for tracing corticospinal tract in rat brain in vivo. METHODS: 0.4 microl volume of 1 mol/L aqueous solution of MnCl(2) was injected into the primary motor cortex of 9 SD rats under stereotaxis. MRI studies were performed for tracing corticospinal tract and other coherent nerve tracts before injection and 24 hours, 48 hours, 72 hours, 7 days after injection respectively using 7.0T Micro-MRI. RESULTS: Corticospinal tract was visualized perfectly from primary motor cortex, thalamus, cerebral peduncle to pons at different time points after Mn(2+) administration, and the best contrast was achieved after 24-48 h. At the same time, a small quantity of Mn(2+) reached the opposite somatosensory cortex through the corpus callosum. CONCLUSION: Manganese enhanced MRI visualizes perfectly the transport of Mn(2+) through axoplasmic flow in corticospinal tracts. This method may be used to investigate the change of corticospinal tract and the functional connectivity between two sides of hemisphere in rat brain.