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.

Purpose

Cardiovascular magnetic resonance imaging exams can be performed during free-breathing. This may be especially important for boys with Duchenne muscular dystrophy (DMD) given their frequently limited breath-hold abilities. The impact of the respiratory compensation method on quantitative measurements of left ventricular (LV) rotational mechanics is incompletely understood. The purpose of this study was to evaluate differences in LV rotational mechanics acquired during breath-holding (BH), free-breathing with averaging (AVG), and free-breathing with respiratory bellows gating (BEL).

Methods

LV short-axis tagged images from healthy subjects (N = 16) and DMD patients (N = 5) were acquired with BH, AVG, and BEL. LV twist and circumferential-longitudinal shear (CL-shear) angle were measured using the Fourier Analysis of STimulated echoes (FAST) method.

Results

Peak LV twist estimates using BEL were significantly lower compared with BH in both healthy subjects (10.2 ± 3.6 ° versus 12.9 ± 2.3 °, P = 0.003) and patients with DMD (8.6 ± 3.6 ° versus 10.5 ± 3.6 °, P = 0.004). AVG results were in between BEL and BH. No significant differences in CL-shear were detected between BEL and BH.

Conclusion

Breath-holding directly affects estimates of peak LV twist, but not CL-shear. Using a free-breathing strategy for the evaluation of cardiac function is important for intrasubject longitudinal studies, intersubject comparisons, and multicenter trials for patients with DMD. Magn Reson Med 77:864-869, 2017. © 2016 International Society for Magnetic Resonance in Medicine.