Complementary radial tagging for improved myocardial tagging contrast

PURPOSE: To develop and evaluate complementary radial tagging (CRT) for improved myocardial tagging contrast. METHODS: We sought to develop and evaluate CRT, which aims to preserve the radial tag contrast throughout the cardiac cycle. Similar to complementary spatial modulation of magnetization, CRT acquires two sets of images with a phase shift in the tag pattern. The combination of a ramped imaging flip angle and image subtraction enhances tag contrast throughout the cardiac cycle. The proposed CRT technique uses a small table shift away from the isocenter to improve the uniformity of the radial tag pattern. We provide a mathematical solution for the optimal table shift and validate the solution in using a retrospective analysis of images from 500 patients in the Cardiac Atlas Project database. RESULTS: CRT simulations, phantom experiments, and in vivo images all demonstrate the improved tag contrast of CRT compared to RT. The retrospective evaluation demonstrated that acceptable CRT images could be acquired in over 98% of the clinical exams. CONCLUSION: The CRT technique improves radial tag contrast throughout the cardiac cycle and should produce high quality tag patterns in nearly all patients.