shimming

Full Definition

Shimming is a critical MRI optimization technique that adjusts the magnetic field to achieve better homogeneity across the imaging volume. In cardiac MRI, effective shimming is essential due to susceptibility artifacts caused by air-tissue interfaces near the heart and lungs. Poor shimming can result in signal dropout, distortion, and banding artifacts that compromise image quality and diagnostic accuracy. Modern scanners use automated shimming algorithms, but manual adjustments may be necessary for optimal cardiac imaging, particularly in patients with metallic implants or unusual anatomy.

In Context

• "Additional shimming was required to eliminate susceptibility artifacts in the inferior wall region." — MRI technical note
• "The protocol specifies manual shimming adjustments for patients with pacemakers." — MRI safety protocol