Goolaub Datta Singh, Tian Ye, van Amerom Joshua F P, Wood John, Detterich Jon, Nayak Krishna S, Macgowan Christopher K
Translational Medicine, The Hospital for Sick Children, Toronto, Ontario, Canada.
Ming Hsieh Department of Electrical and Computer Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California, USA.
J Cardiovasc Magn Reson. 2025 Feb 7;27(1):101856. doi: 10.1016/j.jocmr.2025.101856.
Dynamic fetal cardiovascular MRI (CMR) enables visualization of moving structures to assess congenital heart disease and plan treatment. Low field MRI systems can provide more comfortable platforms for fetal CMR. Here, we demonstrate the feasibility and utility of motion corrected fetal cardiac cine CMR and compare it with real-time CMR at multiple spatial resolutions at 0.55 T.
Ten human pregnancies were scanned at 0.55T on a derated MAGNETOM Aera (Siemens Healthineers, Erlangen, Germany) with spiral steady-state free precession imaging. Real-time images were reconstructed and used for motion correction and fetal cardiac gating followed by cine reconstructions. The signal-to-noise ratio (SNR), image quality, blood-to-myocardium contrast, and contrast-to-noise ratio (CNR) from real-time and cine reconstructions were compared. The effect of acceleration on cine accuracy was assessed by retrospectively undersampling the data and measuring the reconstruction error with the normalized root-mean-squared difference (NRMSD) in five fetuses. Reproducibility of the measurements was assessed by reconstructing cines from two independent windows of data and computing the NRMSD relative to the reference image in five fetuses.
The SNR, CNR, and image quality were better for cines than their corresponding real-time reconstructions. The blood-to-myocardium contrast had no significant difference between real-time and cine reconstructions. With finer spatial resolution, real-time images degraded, and cardiac structures were less conspicuous. NRMSD in cines decreased with increasing scan times across all resolutions (NRMSD = 10 ± 2% for 7 s scan duration). Good consistency (NRMSD = 11 ± 3%) was achieved between independent reconstruction windows.
While this study was performed on an experimental scanner (derated; not commercially available), we have shown that fetal cine CMR is feasible at 0.55T and provides high-quality fetal cardiac images at high spatiotemporal resolutions.
动态胎儿心血管磁共振成像（CMR）能够可视化运动结构，以评估先天性心脏病并规划治疗方案。低场MRI系统可为胎儿CMR提供更舒适的平台。在此，我们展示了运动校正胎儿心脏电影CMR的可行性和实用性，并在0.55T的多个空间分辨率下将其与实时CMR进行比较。
在一台降额使用的MAGNETOM Aera（西门子医疗系统公司，德国埃尔朗根）上，使用螺旋稳态自由进动成像对10例人类妊娠进行0.55T扫描。重建实时图像并用于运动校正和胎儿心脏门控，随后进行电影重建。比较实时和电影重建的信噪比（SNR）、图像质量、血液与心肌对比度以及对比噪声比（CNR）。通过对数据进行回顾性欠采样并测量五名胎儿中具有归一化均方根差（NRMSD）的重建误差，评估加速对电影准确性的影响。通过从两个独立的数据窗口重建电影并计算五名胎儿中相对于参考图像的NRMSD来评估测量的可重复性。
电影的SNR、CNR和图像质量优于其相应的实时重建。实时和电影重建之间的血液与心肌对比度无显著差异。随着空间分辨率变高，实时图像质量下降，心脏结构变得不那么明显。在所有分辨率下，电影中的NRMSD随着扫描时间的增加而降低（扫描持续时间为7秒时，NRMSD = 10 ± 2%）。独立重建窗口之间实现了良好的一致性（NRMSD = 11 ± 3%）。
虽然本研究是在一台实验扫描仪（降额使用；非商业可用）上进行的，但我们已经表明，胎儿电影CMR在0.55T时是可行的，并能在高时空分辨率下提供高质量的胎儿心脏图像。
