FIG. 1.
(a) External calibration using a fully phase-encoded UTE acquisition with broadband excitations spanning the extremely large off-resonance signal induced by metallic implants, which can be used for parallel imaging calibration across all RF offsets (colored Gaussians) of a 3D-MSI acquisition. (b) Self-calibration requires fully sampled calibration regions at each RF offset. (c) External-calibration acquires the fully sampled calibration region only once, allowing for a reduction in data sampling for all RF offsets and shorter scan times.