Comparison of spoiled gradient echo and steady‐state free‐precession imaging for native myocardial T1 mapping using the slice‐interleaved T1 mapping (STONE) sequence. (23rd September 2016) - Jang, Jihye
Abstract: 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. Abstract : Native myocardial T1 measurements acquired using the slice‐interleaved T1 mapping (STONE) sequence with spoiled gradient echo (STONE‐GRE) or balanced steady state free precession (STONE‐SSFP) imaging were compared at 1.5T. The STONE sequence increases recovery time for each slice, improving the SNR of T1 ‐weighted images, thus making it more favorable for GRE imaging. Despite lower SNR of GRE imaging readout compared to SSFP, STONE‐GRE provides similar native myocardial T1 measurements, precision, reproducibility and subjective image quality when compared to STONE‐SSFP at 1.5T.