Motivation: When patients with metallic orthodontic appliances (e.g., braces) are scanned, either images are significantly degraded or the appliance need to be removed and reapplied before and after MRI exams, burdening patients and their parents. Goal(s): Assess whether multi-coil B0 shim arrays can null field offsets in the brain and restore image quality. Approach: Two shim array geometries are simulated on a B0 field map acquired on a patient with braces. A head phantom incorporating braces is then used to test shimming on a 3T scanner. Results: Multi-coil B0 shimming can reduce brain B0 inhomogeneity >4x for global shimming and >6x for slice-optimized shimming. Impact: We explore the use of local B0 shim coils to correct artifacts in brain MRI scans of pediatric patients with metallic orthodontic appliances, enabling the acquisition of high-quality images on these patients without removing their braces or other hardware.
Stockmann et al. (Tue,) studied this question.