Schäper Jessica, Bieri Oliver
Department of Biomedical Engineering, University of Basel, Basel, Switzerland.
Division of Radiological Physics, Department of Radiology, University Hospital Basel, Basel, Switzerland.
Magn Reson Med. 2024 Mar;91(3):1043-1056. doi: 10.1002/mrm.29949. Epub 2023 Nov 27.
To investigate the prospects of a multigradient-echo (mGRE) acquisition for in vivo myelin water imaging at 0.55 T.
Scans were performed on the brain of four healthy volunteers at 0.55 and 3 T, using a 3D mGRE sequence. The myelin water fraction (MWF) was calculated for both field strengths using a nonnegative least squares (NNLS) algorithm, implemented in the qMRLab suite. The quality of these maps as well as single-voxel fits were compared visually for 0.55 and 3 T.
The obtained MWF values at 0.55 T are consistent with previously reported ones at higher field strengths. The MWF maps are a considerable improvement over the ones at 3 T. Example fits show that 0.55 T data is better described by an exponential model than 3 T data, making the assumed multi-exponential model of the NNLS algorithm more accurate.
This first assessment shows that mGRE myelin water imaging at 0.55 T is feasible and has the potential to yield better results than at higher fields.
研究在0.55 T场强下采用多梯度回波（mGRE）采集技术进行体内髓鞘水成像的前景。
使用三维mGRE序列，对4名健康志愿者的大脑分别在0.55 T和3 T场强下进行扫描。利用qMRLab软件包中实现的非负最小二乘法（NNLS）算法计算两种场强下的髓鞘水分数（MWF）。对0.55 T和3 T场强下这些图谱的质量以及单像素拟合结果进行视觉比较。
在0.55 T场强下获得的MWF值与之前在更高场强下报道的值一致。与3 T场强下的图谱相比，0.55 T场强下的MWF图谱有显著改善。示例拟合结果表明，指数模型对0.55 T数据的描述比3 T数据更好，这使得NNLS算法所假定的多指数模型更为准确。
首次评估表明，在0.55 T场强下进行mGRE髓鞘水成像可行，并且有可能比在更高场强下获得更好的结果。
