Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Building 5, Room 112, Bethesda, Maryland 20892-0520, USA.
Phys Chem Chem Phys. 2010 Jun 14;12(22):5779-85. doi: 10.1039/c0cp00157k. Epub 2010 May 11.
We evaluate the feasibility of (1)H nuclear magnetic resonance (NMR) imaging with sub-micron voxel dimensions using a combination of low temperatures and dynamic nuclear polarization (DNP). Experiments are performed on nitroxide-doped glycerol-water at 9.4 T and temperatures below 40 K, using a 30 mW tunable microwave source for DNP. With DNP at 7 K, a 0.5 microL sample yields a (1)H NMR signal-to-noise ratio of 770 in two scans with pulsed spin-lock detection and after 80 db signal attenuation. With reasonable extrapolations, we infer that (1)H NMR signals from 1 microm(3) voxel volumes should be readily detectable, and voxels as small as 0.03 microm(3) may eventually be detectable. Through homonuclear decoupling with a frequency-switched Lee-Goldburg spin echo technique, we obtain 830 Hz (1)H NMR linewidths at low temperatures, implying that pulsed field gradients equal to 0.4 G/d or less would be required during spatial encoding dimensions of an imaging sequence, where d is the resolution in each dimension.
我们评估了（1）H 核磁共振（NMR）成像的可行性，使用低温和动态核极化（DNP）的组合。在 9.4T 和低于 40K 的温度下，在可调谐微波源的作用下对氮氧自由基掺杂的甘油 - 水进行实验。在 7K 时，在经过 80db 信号衰减后，使用脉冲自旋锁定检测，0.5微升样品在两次扫描中产生 770 的（1）H NMR 信号与噪声比。通过合理的推断，我们推断 1 微米（3）的体素体积的（1）H NMR 信号应该很容易被检测到，而体积小至 0.03 微米（3）的体素最终可能被检测到。通过使用频率切换的 Lee-Goldburg 自旋回波技术进行同核去耦，我们在低温下获得了 830Hz 的（1）H NMR 线宽，这意味着在成像序列的空间编码维度中，需要的脉冲场梯度等于 0.4G/d 或更小，其中 d 是每个维度的分辨率。
