O'Donnell Lauren F, Rodriguez Gonzalo G, Lemberskiy Gregory, Yu Zidan, Dergachyova Olga, Cloos Martijn, Madelin Guillaume
Center for Biomedical Imaging, Department of Radiology, NYU Grossman School of Medicine, New York, NY, USA.
NMR Signal Enhancement, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
ArXiv. 2024 Dec 11:arXiv:2412.07006v2.
We developed a new sodium magnetic resonance fingerprinting (Na MRF) method for the simultaneous mapping of and sodium density with built-in (radiofrequency transmission inhomogeneities) and corrections (frequency offsets). We based our Na MRF implementation on a 3D FLORET sequence with 23 radiofrequency pulses. To capture the complex spin dynamics of the Na nucleus, the fingerprint dictionary was simulated using the irreducible spherical tensor operators formalism. The dictionary contained 831,512 entries covering a wide range of factor and parameters. Fingerprint matching was performed using the Pearson correlation and the resulting relaxation maps were weighted with a subset of the highest correlation coefficients corresponding to signal matches for each voxel. Our Na MRF method was compared against reference methods in a 7-compartment phantom, and applied in brain in five healthy volunteers at 7 T. In phantoms, Na MRF produced values comparable to those obtained with reference methods. Average sodium relaxation time values in cerebrospinal fluid, gray matter and white matter across five healthy volunteers were in good agreement with values previously reported in the literature.
我们开发了一种新的钠磁共振指纹图谱（Na MRF）方法，用于同时绘制钠浓度和密度图，并具有内置的B1（射频传输不均匀性）和B0（频率偏移）校正功能。我们的Na MRF实现基于具有23个射频脉冲的3D FLORET序列。为了捕捉钠原子核复杂的自旋动力学，使用不可约球张量算符形式模拟了指纹字典。该字典包含831,512个条目，涵盖了广泛的弛豫因子和化学位移参数。使用皮尔逊相关性进行指纹匹配，并使用与每个体素的信号匹配对应的最高相关系数子集对所得的弛豫图进行加权。我们的Na MRF方法在一个7腔模型中与参考方法进行了比较，并应用于7名健康志愿者的大脑中。在模型中，Na MRF产生的值与参考方法获得的值相当。五名健康志愿者脑脊液、灰质和白质中的平均钠弛豫时间值与文献中先前报道的值高度一致。
