An array of fully-integrated quadrature TX/RX NMR field probes for MRI trajectory mapping

In this paper we present fully-integrated field probes for real-time trajectory mapping during magnetic resonance imaging (MRI) experiments. The field probes co-integrate an NMR microcoil and the required transceiver electronics on a single ASIC manufactured in a 0.13μm CMOS technology. Thanks to an on-chip PLL, power amplifier and low-IF quadrature receiver, all connections to and from the chip carry only low frequency signals allowing for an effective reduction of the magnetic coupling between the field probes and the MRI scanner during imaging. The small form factor and low power consumption of 16.5mW allows for the realization of arrays of field probes, which in contrast to single probes enable the correction of higher order field imperfections. Measured trajectory maps acquired with a prototype array consisting of four probes demonstrate the excellent sensor performance achievable using the proposed approach.