Manganese‐enhanced magnetic resonance imaging (MEMRI): methodological and practical considerations

Manganese‐enhanced MRI (MEMRI) is being increasingly used for MRI in animals due to the unique T 1 contrast that is sensitive to a number of biological processes. Three specific uses of MEMRI have been demonstrated: to visualize activity in the brain and the heart; to trace neuronal specific connections in the brain; and to enhance the brain cytoarchitecture after a systemic dose. Based on an ever‐growing number of applications, MEMRI is proving useful as a new molecular imaging method to visualize functional neural circuits and anatomy as well as function in the brain in vivo . Paramount to the successful application of MEMRI is the ability to deliver Mn 2+ to the site of interest at an appropriate dose and in a time‐efficient manner. A major drawback to the use of Mn 2+ as a contrast agent is its cellular toxicity. Therefore, it is critical to use as low a dose as possible. In the present work the different approaches to MEMRI are reviewed from a practical standpoint. Emphasis is given to the experimental methodology of how to achieve significant, yet safe, amounts of Mn 2+ to the target areas of interest. Copyright © 2004 John Wiley & Sons, Ltd.