A magnetic field monitoring system for MRI using 19F-NMR technique: A preliminary study

To obtain high property MR images, it is crucial to know the magnetic field evolution. Magnetic field monitoring with NMR probes is an effective method to record the magnetic field evolution. The existing monitoring system is based on the proton signal, so a RF shield should be utilized to eliminate the RF interference between monitoring and imaging. However, eddy current will be induced on the shield layer by gradient switching. In this work, a magnetic field monitoring system for MRI using ¹⁹F-NMR is established. The monitoring system mainly consists of probe-head and spectrometer. The probe-head is based on liquid sample C₆F₆, so the RF shield can be omitted without RF interference between monitoring and imaging. A separate spectrometer is employed to enable the monitor system to operate independently. The performance of the monitor system is demonstrated in a home-built 0.3 T MRI system.