Qian Yongxian, Lin Ying-Chia, Chen Xingye, Ge Yulin, Lui Yvonne W, Boada Fernando E
Bernard and Irene Schwartz Center for Biomedical Imaging, Department of Radiology, New York University Grossman School of Medicine, New York, NY, 10016, USA.
Neuroscience Institute, New York University Grossman School of Medicine, New York, NY, 10016, USA.
Sci Rep. 2025 Jul 28;15(1):27427. doi: 10.1038/s41598-025-07800-1.
Sodium magnetic resonance imaging (MRI) is highly sensitive to cellular ionic balance due to tenfold difference in sodium concentration across membranes, actively maintained by the sodium-potassium (Na-K) pump. Disruptions in this pump or membrane integrity, as seen in neurological disorders like epilepsy, multiple sclerosis, bipolar disease, and mild traumatic brain injury, lead to increased intracellular sodium. However, this cellular-level alteration is often masked by the dominant extracellular sodium signal, making it challenging to distinguish sodium populations with mono- vs. bi-exponential transverse (T) decays-especially given the low signal-to-noise ratio (SNR) even at an advanced clinical field of 3 Tesla. Here, we propose a novel technique that leverages intrinsic difference in T decays by acquiring single-quantum images at multiple echo times (TEs) and applying voxel-wise matrix inversion for accurate signal separation. Using numerical models, agar phantoms, and human subjects, we achieved high separation accuracy in phantoms (95.8% for mono-T and 72.5-80.4% for bi-T) and demonstrated clinical feasibility in humans. This approach may enable early detection of neurological disorders and early assessment of treatment responses at the cellular level using sodium MRI at 3 T.
由于细胞膜两侧钠浓度存在10倍差异，并由钠钾（Na-K）泵积极维持，钠磁共振成像（MRI）对细胞离子平衡高度敏感。在癫痫、多发性硬化症、双相情感障碍和轻度创伤性脑损伤等神经系统疾病中，该泵或膜完整性的破坏会导致细胞内钠增加。然而，这种细胞水平的改变通常被占主导地位的细胞外钠信号所掩盖，这使得区分具有单指数与双指数横向（T）衰减的钠群具有挑战性——尤其是考虑到即使在3特斯拉的先进临床场强下，信噪比（SNR）也很低。在此，我们提出了一种新技术，该技术通过在多个回波时间（TE）采集单量子图像并应用体素级矩阵反演来准确分离信号，从而利用T衰减的内在差异。使用数值模型、琼脂体模和人体受试者，我们在体模中实现了高分离精度（单T为95.8%，双T为72.5 - 80.4%），并在人体中证明了临床可行性。这种方法可能能够在3T场强下使用钠MRI在细胞水平上早期检测神经系统疾病并早期评估治疗反应。
