Cardiovascular Magnetic Resonance Unit, Royal Brompton Hospital, Sydney Street, London, SW3 6NP, United Kingdom.
National Heart and Lung Institute, Imperial College, Sydney Street, London, SW3 6NP, United Kingdom.
Magn Reson Med. 2018 Aug;80(2):648-654. doi: 10.1002/mrm.27051. Epub 2017 Dec 19.
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.
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.
There was a greater than 49% increase in the SNR in vivo and in the phantom measurements (in vivo septum, systole: SNR = 8.0 ± 2.2, SNR = 12.0 ± 2.7; diastasis: SNR = 8.1 ± 1.6, SNR = 12.0 ± 3.7). There were no significant differences in helix angle gradient (HAG) (systole: HAG = -0.79 ± 0.07 °/%; HAG = -0.74 ± 0.16 °/%; P = 0.11; diastasis: HAG = -0.63 ± 0.05 °/%; HAG = -0.56 ± 0.14 °/%; P = 0.20), mean diffusivity (MD) in systole (MD = 0.99 ± 0.06 × 10 mm /s, MD = 1.00 ± 0.09 × 10 mm /s, P = 0.23) and secondary eigenvector angulation (E2A) (systole: E2A = 61 ± 10 °; E2A = 63 ± 10 °; P = 0.77; diastasis: E2A = 18 ± 11 °; E2A = 15 ± 8 °; P = 0.20) between the sequences. There was a small difference (≈ 20%) in fractional anisotropy (FA) (systole: FA = 0.49 ± 0.03, FA = 0.41 ± 0.04; P < 0.01; diastasis: FA = 0.66 ± 0.05, FA = 0.55 ± 0.03; P < 0.01) and mean diffusivity in diastasis (10%; MD = 1.00 ± 0.12 × 10 mm /s, MD = 1.10 ± 0.09 × 10 mm /s, P = 0.02).
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.
使用具有平面回波成像（EPI）读取功能的激发回波采集模式（STEAM）的扩散张量心血管磁共振（DT-CMR）是一种低信噪比（SNR）技术，因此通常具有较低的空间分辨率。螺旋轨迹比 EPI 更有效，可以提高 SNR。本研究的目的是比较新型 STEAM 螺旋 DT-CMR 序列与等效的 EPI 技术的性能。
在 3T 下对 11 名健康志愿者进行了 STEAM DT-CMR 序列的实施，该序列采用螺旋读取和缩小的视野。在体内比较了 EPI 和螺旋之间的 DT-CMR 参数和数据质量。在体模和体内进行了 SNR 比较。
体内和体模测量中的 SNR 增加了超过 49%（体内中隔，收缩期：SNR = 8.0 ± 2.2，SNR = 12.0 ± 2.7；舒张期：SNR = 8.1 ± 1.6，SNR = 12.0 ± 3.7）。螺旋角梯度（HAG）没有显著差异（收缩期：HAG = -0.79 ± 0.07 °/%; HAG = -0.74 ± 0.16 °/%; P = 0.11；舒张期：HAG = -0.63 ± 0.05 °/%; HAG = -0.56 ± 0.14 °/%; P = 0.20），收缩期平均弥散度（MD）（MD = 0.99 ± 0.06 × 10 mm /s，MD = 1.00 ± 0.09 × 10 mm /s，P = 0.23）和次要特征向量角（E2A）（收缩期：E2A = 61 ± 10 °；E2A = 63 ± 10 °；P = 0.77；舒张期：E2A = 18 ± 11 °；E2A = 15 ± 8 °；P = 0.20）在两种序列之间没有显著差异。各向异性分数（FA）略有差异（约 20%）（收缩期：FA = 0.49 ± 0.03，FA = 0.41 ± 0.04；P < 0.01；舒张期：FA = 0.66 ± 0.05，FA = 0.55 ± 0.03；P < 0.01），舒张期 MD 也略有差异（10%；MD = 1.00 ± 0.12 × 10 mm /s，MD = 1.10 ± 0.09 × 10 mm /s，P = 0.02）。
这是第一项使用螺旋轨迹进行 DT-CMR STEAM 的研究。使用螺旋而不是更成熟的 EPI 读取来提高 SNR，并且两种序列之间的 DT-CMR 参数大致相似。磁共振医学 80:648-654, 2018. © 2017 国际磁共振学会。
