Wang Xiaoqing, Fan Hongli, Tan Zhengguo, Vasylechko Serge, Yang Edward, Didier Ryne, Afacan Onur, Uecker Martin, Warfield Simon K, Gholipour Ali
Department of Radiology, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts.
Siemens Medical Solutions, Boston, Massachusetts.
Magn Reson Med. 2025 Jun 18. doi: 10.1002/mrm.30604.
To develop a rapid, high-resolution, and distortion-free technique for simultaneous water-fat separation, and mapping of the fetal brain at 3 T.
A 2D multi-echo radial FLASH sequence with blip gradients is adapted for data acquisition during maternal free breathing. A calibrationless model-based reconstruction with sparsity constraints is developed to jointly estimate water, fat, and field maps directly from k-space. This approach was validated and compared to reference methods using numerical and NIST phantoms and data from nine fetuses between 26 and 36 weeks of gestation age.
Both numerical and experimental phantom studies confirm good accuracy and precision. In fetal studies, model-based reconstruction yields quantitative values in close agreement with those from a parallel imaging compressed sensing (PICS) technique using Graph Cut (intra-class correlation coefficient [ICC] = 0.9601), while providing enhanced image detail. Repeated scans confirm good reproducibility (ICC = 0.9213). Compared to multi-echo EPI, the proposed radial technique produces higher-resolution (1.1 1.1 3 mm vs. 2-3 2-3 3 mm ) maps with reduced distortion. Despite differences in motion, resolution, and distortion, values are comparable between the two acquisition strategies (ICC = 0.8049). Additionally, the proposed approach enables the synthesis of high-resolution and distortion-free -weighted images.
This study demonstrates the feasibility of using multi-echo radial FLASH combined with calibrationless model-based reconstruction for motion-robust, distortion-free mapping of the fetal brain at 3T, achieving a nominal resolution of mm within 2 s per slice.
开发一种快速、高分辨率且无失真的技术，用于在3T条件下同时进行胎儿脑内水脂分离及成像。
采用带有跳变梯度的二维多回波径向FLASH序列，在孕妇自由呼吸期间进行数据采集。开发了一种基于无校准模型且带有稀疏约束的重建方法，可直接从k空间联合估计水、脂肪和场图。该方法通过数值模拟、NIST体模以及来自9例孕龄在26至36周胎儿的数据进行验证，并与参考方法进行比较。
数值模拟和实验体模研究均证实了良好的准确性和精确性。在胎儿研究中，基于模型的重建得出的定量值与使用图割的并行成像压缩感知（PICS）技术所得结果高度一致（组内相关系数[ICC]=0.9601），同时提供了增强的图像细节。重复扫描证实了良好的可重复性（ICC=0.9213）。与多回波EPI相比，所提出的径向技术生成的图像分辨率更高（1.1×1.1×3mm vs. 2 - 3×2 - 3×3mm）且失真更小。尽管在运动、分辨率和失真方面存在差异，但两种采集策略所得的 值具有可比性（ICC=0.8049）。此外，所提出的方法能够合成高分辨率且无失真的加权图像。
本研究证明了使用多回波径向FLASH结合基于无校准模型的重建技术，在3T条件下对胎儿脑进行运动稳健、无失真成像的可行性，每切片在2秒内可实现标称分辨率为 mm 。
