Kratzer Fabian J, Flassbeck Sebastian, Nagel Armin M, Behl Nicolas G R, Knowles Benjamin R, Bachert Peter, Ladd Mark E, Schmitter Sebastian
Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany.
Faculty of Physics and Astronomy, Ruprecht-Karls University Heidelberg, Heidelberg, Germany.
Magn Reson Med. 2020 Nov;84(5):2577-2591. doi: 10.1002/mrm.28316. Epub 2020 Jun 18.
To evaluate the feasibility of Na MR fingerprinting (MRF) for simultaneous quantification of T , , , in addition to ΔB .
A framework for sodium relaxometry using MRF at 7T was developed, allowing simultaneous measurement of relaxation times and inhomogeneities in the static field. The technique distinguishes between bi- and monoexponential transverse relaxation and was validated in simulations with respect to the ground truth. In phantom measurements, a resolution of 2 × 2 × 12 mm was achieved within 1 h acquisition time, and the resulting parameter maps were compared to results from reference methods. Relaxation times in five healthy volunteers were measured with a resolution of 4 × 4 × 12 mm .
Phantom experiments revealed an agreement between the relaxation times obtained via Na-MRF and the reference methods. In white matter, a longitudinal relaxation constant of T = 38.9 ± 4.8 ms was found, while values of = 29.2 ± 4.9 ms and = 4.7 ± 1.2 ms were found for the long and short component of the transverse relaxation. In cerebrospinal fluid, T was 67.7 ± 6.3 ms and = 41.5 ± 3.4 ms.
This work demonstrates the feasibility of Na-MRF for relaxometry in sodium MRI in both phantom and in vivo studies. Simultaneous quantification of T , , , and ΔB was possible within a 1 h measurement time.
评估钠磁共振指纹图谱（MRF）在同时定量T、、、以及ΔB方面的可行性。
开发了一种在7T场强下使用MRF进行钠弛豫测量的框架，可同时测量静态场中的弛豫时间和不均匀性。该技术区分双指数和单指数横向弛豫，并在模拟中相对于真实情况进行了验证。在体模测量中，在1小时采集时间内实现了2×2×12毫米的分辨率，并将所得参数图与参考方法的结果进行了比较。对五名健康志愿者的弛豫时间进行了测量，分辨率为4×4×12毫米。
体模实验表明，通过钠MRF获得的弛豫时间与参考方法之间具有一致性。在白质中，纵向弛豫常数T为38.9±4.8毫秒，而横向弛豫的长、短分量的值分别为=29.2±4.9毫秒和=4.7±1.2毫秒。在脑脊液中，T为67.7±6.3毫秒，=41.5±3.4毫秒。
这项工作证明了钠MRF在体模和体内研究中用于钠MRI弛豫测量的可行性。在1小时测量时间内可以同时定量T、、、以及ΔB。
