Optimized magnetic tissue tagging sequence for echo-planar imaging

Magnetic tissue tagging is becoming a very viable non-invasive tool in the assessment of the myocardium. Landmarks are introduced on the reconstructed MR heart image, which are otherwise missing in the cardiac anatomy. Quantification of the myocardial function relies on the accuracy of the tag detection and tracking algorithms. Perfecting the tagging process simplifies the detection and tracking procedure and results in a more reliable assessment of the myocardium. The main goal of this study was to investigate and control factors that govern the persistence, contrast to noise ratio, and morphological properties of magnetic tissue tagging by optimizing an imaging sequence with a perfected group of tags. To accomplish this goal, an algorithm has been developed to optimize the RF excitation pulse associated with the tagging sequence. This algorithm took into account the time duration of the RF pulse, the number of tags, the width of each tag as well as the center-to-center distance between the tags. The flip angle on the tagged region, the gradient properties of the tags profile line, the contrast to noise properties and the persistence of the tag lines over the consecutive frames were also examined.