Investigating Respiration Induced B0 Field Variations in the Thoracic and Lumbar Spinal Cord at 7T

Motivation: Respiration-related B0 variations and their modulation in the thoracolumbar spinal cord (SC) at 7T have not been thoroughly investigated. Knowing B0 variations is crucial for assessing the potential of SC imaging. Goal(s): Quantification of B0 variations in the thoracolumbar SC across different respiratory states and evaluation of the effectiveness of tailored B0 shims in mitigating these variations. Approach: Non-Cartesian respiration-resolved 3D B0 field maps were acquired during free-breathing and employed for B0 shimming using the SC Shimming Toolbox. Results: Tailored B0 shims reduce the B0 variations to approximately 50Hz (standard deviation) across the thoracolumbar SC. Respiration introduces up to 40Hz of additional field-offset. Impact: Our results quantify B0 fluctuations in the thoracolumbar SC and show that customized B0 shims effectively reduce these fluctuations to a standard deviation of around 50Hz. Further investigation of deep breathing is crucial for optimizing shim strategies in future uses.