A double-DANTE tagging sequence for the evaluation of heart wall motion

A magnetic resonance imaging sequence that generates a high-density grid pattern of tags is discussed. In the sequence described, the tag placement occurs by exciting the sample with a DANTE pulse sequence in the presence of a continuous frequency encoding gradient. This results in a set of thin parallel lines whose separation can be controlled by varying either the Dante delay or the gradient strength. The tagging sequence requires less than 10 ms to define a cross-sectional grid. By alternating the phase of the DANTE pulses between 0° and 180°, excitation occurs at four different frequencies, thereby quadrupling the number of tags. The use of a DANTE pulse train provides better frequency selectivity and reduces the bandwidth limitation of the longer binomial pulses