5 Magnetization Transfer

One of several techniques that achieve contrast by preparing the magnetization in some way and then sampling the prepared magnetization via a conventional imaging sequence, magnetization transfer offers advantages that have proven valuable in the study of white matter disorders. In the most common implementation, the magnetization transfer preparation is integrated into a gradient echo pulse sequence, with a conventional gradient echo acquisition serving as a control study. The magnetization transfer (MT) effect can be expressed quantitatively and also evaluated using histogram measures. With the assumption of models for molecular behavior within tissue, fundamental relaxation parameters can theoretically be extracted by solving an inverse problem. Imaging sequences incorporating MT have proven to be relatively easy to implement and to interpret, and have become a common research tool for evaluation of brain disorders. This brief overview will lay out the fundamental assumptions regarding the MT model and will provide suggestions for implementation and analysis of MT studies.