Transcranial manganese delivery for neuronal tract tracing using MEMRI

&NA; There has been a growing interest in the use of manganese‐enhanced MRI (MEMRI) for neuronal tract tracing in mammals, especially in rodents. For this MEMRI application, manganese solutions are usually directly injected into specific brain regions. Recently it was reported that manganese ions can diffuse through intact rat skull. Here the local manganese concentrations in the brain tissue after transcranial manganese application were quantified and the effectiveness of tracing from the area under the skull where delivery occurred was determined. It was established that transcranially applied manganese yields brain tissue enhancement dependent on the location of application on the skull and that manganese that enters the brain transcranially can trace to deeper brain areas. HighlightsManganese ions can pass through certain areas of intact rat skull.The efficiency of the passage is strongly dependent on the applied concentration.This transcranial delivery method allows for neuronal tract tracing.