Favre B, Bonche J P, Meheir H, Peyrin J O
Laboratoire de Biophysique, Faculté de Médecine, Lyon, France.
Magn Reson Med. 1990 Feb;13(2):299-304. doi: 10.1002/mrm.1910130212.
For many years, a number of laboratories have been working on the applications of very low field NMR. In 1985, our laboratory presented the first NMR images using the earth's magnetic field. However, the use of this technique was limited by the weakness of the signal and the disturbing effects of the environment on the signal-to-noise ratio and on the homogeneity of the static magnetic field. Therefore experiments has to be performed in places with low environmental disturbances, such as open country or large parks. In 1986, we installed a new station in Lyon, in the town's hostile environment. Good NMR signals can now be obtained (with a signal-to-noise ratio better than 200 and a time constant T2 better than 3s for 200-mnl water samples and at a temperature of about 40 degrees C). We report the terrace roof of our faculty building. Gradient coils were used to correct the local inhomogeneities of the earth's magnetic field. We show FIDs and MR images of water-filled tubes made with or without these improvements.
多年来，许多实验室一直在研究极低场核磁共振的应用。1985年，我们实验室利用地磁场首次获得了核磁共振图像。然而，这项技术的应用受到信号微弱以及环境对信噪比和静磁场均匀性的干扰影响的限制。因此，实验必须在环境干扰较小的地方进行，比如旷野或大型公园。1986年，我们在里昂一个环境恶劣的城镇安装了一个新的实验站。现在可以获得良好的核磁共振信号（对于200毫升水样，在约40摄氏度的温度下，信噪比优于200，时间常数T2优于3秒）。我们报道了我们教学楼的天台。使用梯度线圈来校正地磁场的局部不均匀性。我们展示了有无这些改进措施时制作的充水管的自由感应衰减信号（FIDs）和磁共振图像。
