Frequency-domain simulation of MR tagging

Simulation of MR images is a useful tool for offline sequence development a nd as an aid to understanding image formation. One particular application o f simulation is MR tagging, which is used for tracking myocardial motion. S imple spatial-domain methods cannot adequately represent effects common in these images, such as motion artifact and signal wrap. An existing frequenc y-domain model is shown to be inappropriate for tagged images, and an exten sion based on the Bloch equations and Fourier shift theorem is described to correct this. Software incorporating the new model is used to generate ide al tag intensity profiles and to accurately simulate tagged images. The shi fted k-space patterns associated with tagged images, and their dependence o n the order of the binomial tagging sequence, are explained. An application of the Fourier shift theorem is suggested that allows more rapid simulatio n of static tagged images.