Comparison of Spoiled Gradient Echo and Steady-State Free-Precession Imaging for Native Myocardial T1 Mapping Using the Slice Interleaved T1 mapping (STONE) Sequence

摘要

Cardiac T1 mapping allows non-invasive imaging of interstitial diffuse fibrosis. Myocardial T1 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 B1 and B0 imperfection, which may result in additional artifacts. Gradient echo (GRE) imaging sequence has been used for myocardial T1 mapping, however its use has been limited to higher magnetic field to compensate for lower signal-to-noise ratio (SNR) of GRE vs. SSFP imaging. A slice-interleaved T1 mapping (STONE) sequence with SSFP readout (STONE-SSFP) has been recently proposed for native myocardial T1 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 T1 mapping using STONE with GRE imaging readout (STONE-GRE) at 1.5T. Numerical simulations, phantom and in-vivo imaging were performed to compare the performance of STONE-GRE and STONE-SSFP for native myocardial T1 mapping at 1.5T. In numerical simulations, STONE-SSFP shows sensitivity to both T2 and off-resonance. Despite insensitivity of GRE imaging to T2, STONE-GRE remains sensitive to T2 due to the dependence of the inversion pulse performance on T2. In the phantom study, STONE-GRE had inferior accuracy, precision, and similar repeatability as compared to STONE-SSFP. In in-vivo studies, STONE-GRE and STONE-SSFP had similar myocardial native T1 times, precision, repeatability and subjective T1 map quality. Despite lower SNR of GRE imaging readout compared to SSFP, STONE-GRE provides similar native myocardial T1 measurements, precision, repeatability and subjective image quality when compared to STONE-SSFP at 1.5T.