A stitching method for dynamic field monitoring using NMR probes

Motivation: NMR field probe methods for field monitoring are limited by probe signal loss due to relaxation, dephasing, or both. Goal(s): To develop a method for characterizing sequences with higher resolution or readout length than allowed by current field monitoring approaches. Approach: Long-duration 2D spiral readout gradients were characterized by acquiring and stitching multiple segment-specific dynamic field measurements per segmentation of the readout gradient determined by a signal loss model. Results: For both long-duration and ultrahigh-resolution readouts, our method resulted in plausible 0th-2nd order dynamic field measurements throughout the entire spiral readout, correcting erroneous k-space traversal observed with a traditional approach. Impact: The proposed stitching method provides an effective means to characterize challenging imaging gradients using commercially available hardware and without assuming a linear gradient system, thereby having utility for dynamic field measurements in ultrahigh-resolution MRI using a standard field monitoring system.