title: Feasibility of fat-saturated T2-weighted magnetic resonance imaging with slice encoding for metal artifact correction (SEMAC) at 3T.
abstract: OBJECTIVE
  Fluid-sensitive MR imaging in postoperative evaluation is important, however, metallic artifacts is inevitable. The purpose is to investigate the feasibility of fat-saturated slice encoding for metal artifact correction (SEMAC)-corrected T2-weighted magnetic resonance (MR) at 3T in patients with spinal prostheses.
  
  
  METHODS
  Following institutional review board approval, 27 SEMAC-encoded spinal MRs between September 2012 and October 2013 in patients with spinal metallic prostheses were analyzed. The MR images were scanned on a 3T MR system including SEMAC-corrected and uncorrected fast spin echo (FSE) T2-weighted MR images with fat-saturation. Two musculoskeletal radiologists compared the image sets and qualitatively analyzed the images using a five-point scale in terms of artifact reduction around the prosthesis, visualization of the prosthesis and pedicle, and intervertebral neural foramina. Quantitative assessments were performed by calculating the ratio of signal intensity from the fixated vertebra and that from upper level vertebra. For statistical analyses, paired t-test was used.
  
  
  RESULTS
  Fat-saturated SEMAC-corrected T2-weighted MR images enabled significantly improved metallic artifact reduction (P<0.05). Quantitative evaluation of the signal intensity ratio of screw-fixated vertebra and upper level vertebra showed a significantly lower ratio on fat-saturated SEMAC images (P<0.05), however, the high signal intensity of signal pile-up could be not completely corrected.
  
  
  CONCLUSIONS
  SEMAC correction in fat-suppressed T2-weighted MR images can overcome the signal loss of metallic artifacts and provide improved delineation of the pedicle screw and peri-prosthetic region. Signal pile-up, however, could not be corrected completely, therefore readers should be cautious in the evaluation of marrow around the prosthesis.
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Medical Convergence Research Institute, and Severance Biomedical Science Institute, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul, 120-752 Republic of Korea.
authors.forename: Young Han
authors.initials: YH
authors.lastname: Lee
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Medical Convergence Research Institute, and Severance Biomedical Science Institute, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul, 120-752 Republic of Korea.
authors.forename: Daekeon
authors.initials: D
authors.lastname: Lim
authors.affiliation: Clinical Science, Philips Healthcare, Republic of Korea; Graduate school of Biomedical science & engineering, Hanyang University, Seoul, Republic of Korea.
authors.forename: Eunju
authors.initials: E
authors.lastname: Kim
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Medical Convergence Research Institute, and Severance Biomedical Science Institute, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul, 120-752 Republic of Korea.
authors.forename: Sungjun
authors.initials: S
authors.lastname: Kim
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Medical Convergence Research Institute, and Severance Biomedical Science Institute, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul, 120-752 Republic of Korea.
authors.forename: Ho-Taek
authors.initials: HT
authors.lastname: Song
authors.affiliation: Department of Radiology, Research Institute of Radiological Science, Medical Convergence Research Institute, and Severance Biomedical Science Institute, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul, 120-752 Republic of Korea. Electronic address: jss@yumc.yonsei.ac.kr.
authors.forename: Jin-Suck
authors.initials: JS
authors.lastname: Suh
mesh_terms: D000273:Adipose Tissue / Q000473:pathology*; D000328:Adult; D000368:Aged; D016477:Artifacts; D001416:Back Pain; D001853:Bone Marrow / Q000473:pathology; D001863:Bone Screws; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008670:Metals / Q000737:chemistry*; D008875:Middle Aged; D019736:Prostheses and Implants; D012815:Signal Processing, Computer-Assisted; D013123:Spinal Fusion / Q000295:instrumentation*; D013131:Spine / Q000473:pathology*
chemical_list: D008670:Metals
keywords: Fat suppression; Magnetic resonance; Metallic artifact reduction; Metallic artifacts; Slice encoding for metal artifact correction