Cardiovascular Research Center, Massachusetts General Hospital, Charlestown, Massachusetts, USA.
Department of Medicine, Harvard Medical School, Boston, Massachusetts, USA.
Magn Reson Med. 2021 May;85(5):2634-2648. doi: 10.1002/mrm.28611. Epub 2020 Nov 30.
We aimed to develop a novel free-breathing cardiac diffusion tensor MRI (DT-MRI) approach, M2-MT-MOCO, capable of whole left ventricular coverage that leverages second-order motion compensation (M2) diffusion encoding and multitasking (MT) framework to efficiently correct for respiratory motion (MOCO).
Imaging was performed in 16 healthy volunteers and 3 heart failure patients with symptomatic dyspnea. The healthy volunteers were scanned to compare the accuracy of interleaved multislice coverage of the entire left ventricle with a single-slice acquisition and the accuracy of the free-breathing conventional MOCO and MT-MOCO approaches with reference breath-hold DT-MRI. Mean diffusivity (MD), fractional anisotropy (FA), helix angle transmurality (HAT), and intrascan repeatability were quantified and compared.
In all subjects, free-breathing M2-MT-MOCO DT-MRI yielded DWI of the entire left ventricle without bulk motion-induced signal loss. No significant differences were seen in the global values of MD, FA, and HAT in the multislice and single-slice acquisitions. Furthermore, global quantification of MD, FA, and HAT were also not significantly different between the MT-MOCO and breath-hold, whereas conventional MOCO yielded significant differences in MD, FA, and HAT with MT-MOCO and FA with breath-hold. In heart failure patients, M2-MT-MOCO DT-MRI was feasible yielding higher MD, lower FA, and lower HAT compared with healthy volunteers. Substantial agreement was found between repeated scans across all subjects for MT-MOCO.
M2-MT-MOCO enables free-breathing DT-MRI of the entire left ventricle in 10 min, while preserving quantification of myocardial microstructure compared to breath-held and single-slice acquisitions and is feasible in heart failure patients.
我们旨在开发一种新颖的自由呼吸心脏扩散张量 MRI（DT-MRI）方法，即 M2-MT-MOCO，它能够实现整个左心室的全覆盖，利用二阶运动补偿（M2）扩散编码和多任务（MT）框架来有效地纠正呼吸运动（MOCO）。
在 16 名健康志愿者和 3 名有症状呼吸困难的心力衰竭患者中进行了成像。对健康志愿者进行扫描，以比较整个左心室的交错多层覆盖与单次采集的准确性，以及自由呼吸常规 MOCO 和 MT-MOCO 方法与参考屏气 DT-MRI 的准确性。量化并比较了平均扩散系数（MD）、各向异性分数（FA）、螺旋角透壁性（HAT）和扫描内重复性。
在所有受试者中，自由呼吸的 M2-MT-MOCO DT-MRI 产生了整个左心室的 DWI，没有大块运动引起的信号丢失。在多层和单层采集的全局 MD、FA 和 HAT 值中没有观察到显著差异。此外，MT-MOCO 与屏气之间 MD、FA 和 HAT 的全局定量也没有显著差异，而常规 MOCO 在 MD、FA 和 HAT 方面与 MT-MOCO 以及 FA 与屏气之间存在显著差异。在心力衰竭患者中，与健康志愿者相比，M2-MT-MOCO DT-MRI 是可行的，其 MD 值较高，FA 值较低，HAT 值较低。在所有受试者中，MT-MOCO 的重复扫描之间存在实质性的一致性。
M2-MT-MOCO 能够在 10 分钟内实现整个左心室的自由呼吸 DT-MRI，同时与屏气和单层采集相比，保留了心肌微观结构的定量，并且在心力衰竭患者中是可行的。
