Diffusion tensor cardiovascular magnetic resonance with a spiral trajectory: An in vivo comparison of echo planar and spiral stimulated echo sequences

Purpose Diffusion tensor cardiovascular MR (DT‐CMR) using stimulated echo acquisition mode (STEAM) with echo‐planar‐imaging (EPI) readouts is a low signal‐to‐noise‐ratio (SNR) technique and therefore typically has a low spatial resolution. Spiral trajectories are more efficient than EPI, and could increase the SNR. The purpose of this study was to compare the performance of a novel STEAM spiral DT‐CMR sequence with an equivalent established EPI technique. Methods A STEAM DT‐CMR sequence was implemented with a spiral readout and a reduced field of view. An in vivo comparison of DT‐CMR parameters and data quality between EPI and spiral was performed in 11 healthy volunteers imaged in peak systole and diastasis at 3 T. The SNR was compared in a phantom and in vivo. Results There was a greater than 49% increase in the SNR in vivo and in the phantom measurements (in vivo septum, systole: SNR EPI = 8.0 ± 2.2, SNR spiral = 12.0 ± 2.7; diastasis: SNR EPI = 8.1 ± 1.6, SNR spiral = 12.0 ± 3.7). There were no significant differences in helix angle gradient (HAG) (systole: HAG EPI = −0.79 ± 0.07 °/%; HAG spiral = −0.74 ± 0.16 °/%; P = 0.11; diastasis: HAG EPI = −0.63 ± 0.05 °/%; HAG spiral = −0.56 ± 0.14 °/%; P = 0.20), mean diffusivity (MD) in systole (MD EPI = 0.99 ± 0.06 × 10 −3 mm 2 /s, MD spiral = 1.00 ± 0.09 × 10 −3 mm 2 /s, P = 0.23) and secondary eigenvector angulation (E2A) (systole: E2A EPI = 61 ± 10 °; E2A spiral = 63 ± 10 °; P = 0.77; diastasis: E2A EPI = 18 ± 11 °; E2A spiral = 15 ± 8 °; P = 0.20) between the sequences. There was a small difference (≈ 20%) in fractional anisotropy (FA) (systole: FA EPI = 0.49 ± 0.03, FA spiral = 0.41 ± 0.04; P < 0.01; diastasis: FA EPI = 0.66 ± 0.05, FA spiral = 0.55 ± 0.03; P < 0.01) and mean diffusivity in diastasis (10%; MD EPI = 1.00 ± 0.12 × 10 −3 mm 2 /s, MD spiral = 1.10 ± 0.09 × 10 −3 mm 2 /s, P = 0.02). Conclusion This is the first study to demonstrate DT‐CMR STEAM using a spiral trajectory. The SNR was increased by using a spiral rather than the more established EPI readout, and the DT‐CMR parameters were largely similar between the two sequences. Magn Reson Med 80:648–654, 2018. © 2017 International Society for Magnetic Resonance in Medicine.