MR Imaging Near Metallic Implants Using MAVRIC SL

Abstract

Rationale and Objectives To compare the effectiveness of MAVRIC SL with conventional 2D-FSE MR techniques at 3T in imaging patients with a variety of metallic implants. Materials and Methods Twenty-one 3T MR studies were obtained in 19 patients with different types of metal implants. Paired MAVRIC SL and 2D-FSE sequences were reviewed by 2 radiologists, and compared for in-plane and through-plane metal artifact, visualization of the bone implant interface and surrounding soft tissues, blurring, and overall image quality using a 2-tailed Wilcoxon signed rank test. The area of artifact on paired images was measured and compared using a paired Wilcoxon signed rank test. Changes in patient management resulting from MAVRIC SL imaging were documented. Results Significantly less in-plane and through-plane artifact was seen with MAVRIC SL, with improved visualization of the bone-implant interface and surrounding soft tissues, and superior overall image quality (p = 0.0001). Increased blurring was seen with MAVRIC SL (p=0.0016). MAVRIC SL significantly decreased the image artifact compared to 2D-FSE (p=0.0001). Inclusion of MAVRIC SL to the imaging protocol determined the need for surgery or type of surgery in 5 patients, and ruled out the need for surgery in 13 patients. In 3 patients the area of interest was well seen on both MAVRIC SL and 2D-FSE images, so the addition of MAVRIC had no effect on patient management. Conclusion Imaging around metal implants with MAVRIC SL at 3T significantly improved image quality and decreased image artifact compared to conventional 2D-FSE imaging techniques, and directly impacted patient management.

Novel MR imaging method – MAVRIC – for metal artifact suppression after joint replacement in musculoskeletal tumor patients

“…Artifact was defined as areas of signal void pile-up or geometric distortion. Images were graded on a five-point scale from −2 to +2, where lower score suggested better outcome for MAVRIC acquisitions, which was previously reported by Gutierrez et al [ 8 ]. −2 indicate that MAVRIC is significantly better, and −1 meant somewhat better compared to STIR.…”

Advances in MRI around metal

“…) . Inclusion of MAVRIC or SEMAC to the imaging protocol allowed determining the need for surgery, and the type of surgery . Exemplary MR protocols for the spine, hip, and knee are presented in Table .…”

Fat-suppressed MR Imaging of the Spine for Metal Artifact Reduction at 3T: Comparison of STIR and Slice Encoding for Metal Artifact Correction Fat-suppressed T₂-weighted Images

“… 3 Conventional principles of metallic MR artifact reduction techniques include magnetic field strength, pulse sequence type, voxel size, echo train length, and bandwidth. 4 , 5 Advanced metal artifact-reducing MR techniques have proven useful in overcoming these metallic artifacts, including slice encoding for metal artifact correction (SEMAC), multi-acquisition variable-resonance image combination (MAVRIC), a combination of SEMAC and MAVRIC, 6 – 13 and iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL). 14 …”