MR Imaging Near Orthopedic Implants using Slice-Encoding for Metal Artifact Correction & Off-Resonance Suppression

Chiel Johan den Harder¹, Ulrike A. Blume¹, Clemens Bos²

Slice-Encoding for Metal Artifact Correction (SEMAC) has been proposed for reducing image distortions near metal implants. In SEMAC, the number of through-plane phase encoding steps determines the frequency range for which slice distortions are corrected. Signals with frequencies outside this range will alias in through-plane direction. Here, SEMAC and Off-Resonance Suppression (ORS) are combined to limit signal selection to a confined frequency range and thus prevent back-folding. Phantom and in-vivo experiments show that ORS allows substantial reduction of phase encoding steps to obtain SEMAC images without back-folding. The resulting imaging time reduction supports the clinical utility of SEMAC.