Evaluation of Metal-Artifact Reduction Techniques at 7T: Hardware adaption, phantom study, and preliminary in vivo results

Motivation: Advanced metal-artifact reduction sequences (MARS) are currently only available in parallel transmission (pTx) research mode at 7T, while clinically approved RF coils are single-channel transmit (sTx) coils. Goal(s): Our goal was to build an adapter to connect a sTx knee coil to a pTx system, and to evaluate MARS techniques in phantom and in vivo scans. Approach: An evaluation of artifact reduction using advanced MARS techniques was performed in a phantom study. Knees of three volunteers with metallic suture plates were imaged. Results: Optimized bandwidth and view-angle-tilting (VAT) effectively reduced metal artifacts while keeping acquisition time and SAR load acceptable. Impact: A hardware adaption for connecting a sTx coil to a pTx system was evaluated for safe in vivo usage. The application of MARS was demonstrated for the first time at 7T in volunteers with metallic suture plates after ACL reconstruction.