title: Usefulness of slice encoding for metal artifact correction (SEMAC) for reducing metallic artifacts in 3-T MRI.
abstract: OBJECTIVE
  The purpose of the study was to assess the usefulness of slice encoding for metal artifact correction (SEMAC) in 3.0-T magnetic resonance (MR) in minimizing metallic artifacts in patients with spinal prostheses.
  
  
  METHODS
  Institutional review board approval and informed consent were obtained for this study. Twenty-seven spine MR scans were performed with metal artifact reduction SEMAC between May 2011 and July 2012 in patients with metallic devices. The MR scans were performed on a 3-T MR system (Achieva; Philips Healthcare, Best, the Netherlands) including SEMAC-corrected T2-weighted axial/sagittal images and two-dimensional fast spin echo (FSE) axial/sagittal images. The SEMAC-corrected images were compared to conventional T2-weighted FSE images. Two musculoskeletal radiologists qualitatively analyzed the images in terms of visualization of the pedicle, vertebral body, dural sac, intervertebral disc, intervertebral neural foramina, screws and metallic artifacts. The paired images were rated using a 5-point scale. P values less than .05 were considered to indicate statistically significant differences.
  
  
  RESULTS
  The SEMAC-corrected MR images significantly reduced the metal-related artifacts. The T2-weighted images with SEMAC sequences enabled significantly improved periprosthetic visualizations of the pedicle, vertebral body, dural sac and neural foramina, with the exception of the intervertebral disc (P<.05). In addition, there was significant improvement in prosthesis visualization (P<.05).
  
  
  CONCLUSIONS
  MR images with SEMAC can reduce metal-related artifacts, providing improved delineation of the prosthesis and periprosthetic region. However, for the evaluation of the intervertebral disc, the SEMAC-corrected MR images showed no significant benefits.
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Medical Convergence Research Institute, and Severance Biomedical Science Institute, Yonsei University College of Medicine, 250 Seongsanno, Seodaemun-gu, Seoul 120-752, Republic of Korea.
authors.forename: Young Han
authors.initials: YH
authors.lastname: Lee
authors.forename: Daekeon
authors.initials: D
authors.lastname: Lim
authors.forename: Eunju
authors.initials: E
authors.lastname: Kim
authors.forename: Sungjun
authors.initials: S
authors.lastname: Kim
authors.forename: Ho-Taek
authors.initials: HT
authors.lastname: Song
authors.forename: Jin-Suck
authors.initials: JS
authors.lastname: Suh
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D016477:Artifacts; D001863:Bone Screws; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D007405:Intervertebral Disc Displacement / Q000473:pathology* / Q000601:surgery*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008670:Metals; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted; D013123:Spinal Fusion / Q000295:instrumentation
chemical_list: D008670:Metals