title: SEMAC: Slice Encoding for Metal Artifact Correction in MRI.
abstract: Magnetic resonance imaging (MRI) near metallic implants remains an unmet need because of severe artifacts, which mainly stem from large metal-induced field inhomogeneities. This work addresses MRI near metallic implants with an innovative imaging technique called "Slice Encoding for Metal Artifact Correction" (SEMAC). The SEMAC technique corrects metal artifacts via robust encoding of each excited slice against metal-induced field inhomogeneities. The robust slice encoding is achieved by extending a view-angle-tilting (VAT) spin-echo sequence with additional z-phase encoding. Although the VAT compensation gradient suppresses most in-plane distortions, the z-phase encoding fully resolves distorted excitation profiles that cause through-plane distortions. By positioning all spins in a region-of-interest to their actual spatial locations, the through-plane distortions can be corrected by summing up the resolved spins in each voxel. The SEMAC technique does not require additional hardware and can be deployed to the large installed base of whole-body MRI systems. The efficacy of the SEMAC technique in eliminating metal-induced distortions with feasible scan times is validated in phantom and in vivo spine and knee studies.
authors.affiliation: Department of Radiology, Stanford University, Stanford, CA 94305-5488, USA. wenmiao.lu@gmail.com
authors.forename: Wenmiao
authors.initials: W
authors.lastname: Lu
authors.forename: Kim Butts
authors.initials: KB
authors.lastname: Pauly
authors.forename: Garry E
authors.initials: GE
authors.lastname: Gold
authors.forename: John M
authors.initials: JM
authors.lastname: Pauly
authors.forename: Brian A
authors.initials: BA
authors.lastname: Hargreaves
mesh_terms: D000465:Algorithms; D016477:Artifacts; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D008670:Metals; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted
chemical_list: D008670:Metals