Comparison of spoiled gradient echo and steady-state free-precession imaging for native myocardial T-1 mapping using the slice-interleaved T-1 mapping (STONE) sequence

摘要

Cardiac T-1 mapping allows non-invasive imaging of interstitial diffuse fibrosis. Myocardial T-1 is commonly calculated by voxel-wise fitting of the images acquired using balanced steady-state free precession (SSFP) after an inversion pulse. However, SSFP imaging is sensitive to B-1 and B-0 imperfection, which may result in additional artifacts. A gradient echo (GRE) imaging sequence has been used for myocardial T-1 mapping; however, its use has been limited to higher magnetic field to compensate for the lower signal-to-noise ratio (SNR) of GRE versus SSFP imaging. A slice-interleaved T-1 mapping (STONE) sequence with SSFP readout (STONE-SSFP) has been recently proposed for native myocardial T-1 mapping, which allows longer recovery of magnetization (>8 R-R) after each inversion pulse. In this study, we hypothesize that a longer recovery allows higher SNR and enables native myocardial T-1 mapping using STONE with GRE imaging readout (STONE-GRE) at 1.5T. Numerical simulations and phantom and in vivo imaging were performed to compare the performance of STONE-GRE and STONE-SSFP for native myocardial T-1 mapping at 1.5T. In numerical simulations, STONE-SSFP shows sensitivity to both T-2 and off resonance. Despite the insensitivity of GRE imaging to T-2, STONE-GRE remains sensitive to T-2 due to the dependence of the inversion pulse performance on T-2. In the phantom study, STONE-GRE had inferior accuracy and precision and similar repeatability as compared with STONE-SSFP. In in vivo studies, STONE-GRE and STONE-SSFP had similar myocardial native T-1 times, precisions, repeatabilities and subjective T-1 map qualities. Despite the lower SNR of the GRE imaging readout compared with SSFP, STONE-GRE provides similar native myocardial T-1 measurements, precision, repeatability, and subjective image quality when compared with STONE-SSFP at 1.5T.