Cardiac MRI T₂ mapping with heart phase acquisition and improved motion-sensitized driven equilibrium blood...

Cardiovascular magnetic resonance (CMR) imaging relies on T₂ mapping to assess myocardial tissue properties. However, T₂ maps are subject to motion artifacts and signal interference, prompting exploration of techniques such as gradient-spin-echo (GraSE) sequences, heart phase acquisition, and dark blood (DB) imaging to improve image quality and reliability.

This prospective study evaluates the T₂ relaxation time (T₂) variability and the image quality of T₂ maps obtained in end-systole and end-diastole with and without fat saturation (FS), using GraSE sequence in CMR imaging. Furthermore, improved motion-sensitized driven-equilibrium (iMSDE) was compared with double inversion recovery (DIR) as an alternative DB technique.

Five variants of the DB GraSE sequence were developed and performed on a 1.5 Tesla MRI scanner. Forty-four healthy volunteers prospectively underwent the following sequences: GraSE in end-diastole (GraSE-ED), GraSE-ED with FS (GraSE-ED-FS), GraSE in end-systole (GraSE-ES), GraSE-ES with FS (GraSE-ES-FS), and commercial GraSE-ED (GraSE-CO). Four GraSE variants utilized iMSDE technique, while GraSE-CO used DIR for blood suppression. T₂, image quality, and visual artifacts were measured.

Ten volunteers were excluded due to image artifacts or missing datasets. Among the remaining 34 participants, the mean global T₂ was measured. No significant differences were seen among all variants (P > .05 for all comparisons). Intra- and inter-reader agreement of global T₂ values for all GraSE sequence were very good (r > 0.8 for both). Image quality was rated moderate or good for all variants of GraSE sequences. A lower incidence of artifacts was observed in end-systolic compared to end-diastolic imaging.

All variants of GraSE sequence are highly reproducible and myocardial T₂ values did not significantly differ with heart phase. iMSDE is feasible as an alternative DB technique for T₂ mapping enabling acquisition in systole, which shows a lower incidence of artifacts compared to diastole.