In vivo neuronal tract tracing using manganese‐enhanced magnetic resonance imaging

Abstract
Development of efficient imaging techniques to trace neuro nal connections would be very useful. Manganese ion (Mn2+) is an excellent T1 contrast agent for magnetic resonance imaging (MRI). Four reports utilizing radioactive Mn2+ in fish and rat brain indicate that Mn2+ may be useful for tracing neuronal connections. Therefore, the purpose of this work was to determine if Mn2+ can be used as an in vivo MRI neuronal tract tracer. The results indicate that topical admin istration of MnCI2 solution to the naris of mice as well as to the retinal ganglion cells via intravitreal injection leads to en hancement of contrast along the respective pathways. There fore, application of Mn2+ to neurons allows the use of MRI to visualize neuronal connections.