Department of Radiation Oncology, University of Iowa, Iowa City, IA, USA.
Division of Free Radical and Radiation Biology, Department of Radiation Oncology, The University of Iowa Hospitals and Clinics, Iowa City, IA, 52242-1181, USA.
Sci Rep. 2021 Oct 21;11(1):20817. doi: 10.1038/s41598-021-00305-7.
T* relaxation is an intrinsic magnetic resonance imaging (MRI) parameter that is sensitive to local magnetic field inhomogeneities created by the deposition of endogenous paramagnetic material (e.g. iron). Recent studies suggest that T* mapping is sensitive to iron oxidation state. In this study, we evaluate the spin state-dependence of T* relaxation using T* mapping. We experimentally tested this physical principle using a series of phantom experiments showing that T* relaxation times are directly proportional to the spin magnetic moment of different transition metals along with their associated magnetic susceptibility. We previously showed that T* relaxation time can detect the oxidation of Fe. In this paper, we demonstrate that T* relaxation times are significantly longer for the diamagnetic, d metal Ga, compared to the paramagnetic, d metal Fe. We also show in a cell culture model that cells supplemented with Ga (S = 0) have a significantly longer relaxation time compared to cells supplemented with Fe (S = 5/2). These data support the hypothesis that dipole-dipole interactions between protons and electrons are driven by the strength of the electron spin magnetic moment in the surrounding environment giving rise to T* relaxation.
T弛豫是一种固有磁共振成像（MRI）参数，对由内源性顺磁物质（如铁）沉积引起的局部磁场不均匀性敏感。最近的研究表明，T映射对铁氧化态敏感。在这项研究中，我们使用 T映射来评估 T弛豫对自旋态的依赖性。我们通过一系列的体模实验验证了这一物理原理，结果表明 T弛豫时间与不同过渡金属的自旋磁矩及其相关磁化率直接成正比。我们之前已经表明 T弛豫时间可以检测铁的氧化。在本文中，我们证明与顺磁性 d 金属 Fe 相比，非磁性 d 金属 Ga 的 T弛豫时间显著更长。我们还在细胞培养模型中表明，补充 Ga（S=0）的细胞的弛豫时间明显长于补充 Fe（S=5/2）的细胞。这些数据支持了这样一种假设，即质子和电子之间的偶极-偶极相互作用是由周围环境中电子自旋磁矩的强度驱动的，从而导致 T弛豫。
