Common k-space acquisition: a method to improve myocardial grid-tag contrast.

A current limitation of many myocardial tag acquisitions employing SPAMM encoding is the relatively rapid loss of tag contrast over the cardiac cycle. Acquisition schemes that apply line tags produce prolonged tag contrast compared with directly excited grid tags. However, a grid-tag series can be generated by combining two orthogonal line-tag series. To be time efficient, each line-tag series can be acquired with the read gradient oriented perpendicular to the line-tag direction. There are several disadvantages associated with this approach, including the requirement to avoid signal fold-over and that fat shift artifacts appear in different directions in each line-tag series. Presented here is a method of applying separate line tags that does not require interchanging the read and phase encoding gradients and does not extend the scan time compared with a conventional grid-tag acquisition. Additionally, the means of generating grid tags results in a doubling of the tag contrast to noise ratio compared a line-tag set. Computer simulations are presented along with phantom and volunteer scans.