Los Alamos National Laboratory, Applied Modern Physics Group, MS D454, Los Alamos, NM 87545, United States.
J Magn Reson. 2013 Aug;233:103-6. doi: 10.1016/j.jmr.2013.05.012. Epub 2013 Jun 7.
Ultra-low field (ULF) MRI as an alternative to high field MRI can find some niche applications where high field is a liability. Previously we demonstrated hand images with a non-cryogenic ULF MRI system, but such a system was restrictive to the size of the imaging objects. We have modified the previous setup to increase the imaging volume and demonstrate the image of human hand near the wrist area. One goal for the demonstration is the evaluation of quality of larger bone structure to project image quality to other parts of extremities, such as elbows, shoulders, and knees. We found that after 12 min of acquisition, the image quality was quite satisfactory. To achieve this image quality, several problems were solved that appeared in the new system. The increase in the imaging volume size led to an increase in transient time and various measures were taken to reduce this time. We also explored a method of overcoming the artifacts and image quality reduction arising from field drifts present in the system due to heating of the coils. We believe that our results can be useful for evaluation of diagnostic capability of non-cryogenic ULF MRI of extremities and other parts of the body. The system can be also applied to image animals and tissues.
超低频（ULF）MRI 可以替代高场 MRI，在一些高场是不利因素的应用中可以找到一些利基应用。之前，我们使用非低温 ULF MRI 系统展示了手部图像，但这样的系统对成像物体的大小有限制。我们已经修改了之前的设置，以增加成像体积，并展示了靠近手腕区域的人手图像。展示的一个目标是评估更大骨结构的质量，以将图像质量投影到四肢的其他部位，如肘部、肩部和膝盖。我们发现，在采集 12 分钟后，图像质量相当令人满意。为了达到这种图像质量，我们解决了在新系统中出现的几个问题。成像体积的增加导致瞬态时间的增加，因此采取了各种措施来减少这段时间。我们还探索了一种克服由于线圈加热而导致的场漂移引起的伪影和图像质量降低的方法。我们相信，我们的结果可以用于评估非低温 ULF MRI 对四肢和身体其他部位的诊断能力。该系统还可以应用于动物和组织成像。
