title: Reducing metallic artefacts in post-operative spinal imaging: slice encoding for metal artefact correction with dual-source parallel radiofrequency excitation MRI at 3.0 T.
abstract: OBJECTIVE
  To compare the effects of metal artefacts and acquisition time among slice encoding for metal artefact correction (SEMAC), SEMAC with dual-source parallel radiofrequency (SEMAC-DSPRF) transmission and fast spin echo (FSE) images using 3.0-T MRI.
  
  
  METHODS
  The signal-to-noise ratio (SNR) was calculated in a phantom study using a pedicle screw. A total of 16 patients who underwent spinal surgery using pedicle screws were included in the clinical study. T1 weighted FSE, SEMAC and SEMAC-DSPRF images were obtained. Four imaging findings (visibility of the dural sac, neural foramens, bone-implant interface and overall artefacts) were evaluated by using five-point scales independently by two observers. The mean scan time was recorded.
  
  
  RESULTS
  The mean SNR was 71.2, 25.7 and 28.4 for FSE, SEMAC and SEMAC-DSPRF images, respectively. FSE images were ranked lower than SEMAC and SEMAC-DSPRF images, and ranking of SEMAC and SEMAC-DSPRF images did not differ statistically for all four imaging findings. The mean scan time was 9 min 51 s and 6 min 31 s for SEMAC and SEMAC-DSPRF images, respectively.
  
  
  CONCLUSIONS
  SEMAC can reduce metallic artefacts and improve the visualisation of anatomical structures around metal implants. An additional DSPRF technique can reduce the acquisition time of SEMAC images without the loss of SNR and image quality.
  
  
  CONCLUSIONS
  This study demonstrates that the use of the DSPRF transmission technique can reduce the acquisition time of SEMAC images without loss of image quality in patients with metal implants.
authors.affiliation: Department of Radiology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Kangnam-ku, Seoul, Republic of Korea.
authors.forename: K D
authors.initials: KD
authors.lastname: Song
authors.forename: Y C
authors.initials: YC
authors.lastname: Yoon
authors.forename: J
authors.initials: J
authors.lastname: Park
mesh_terms: D000368:Aged; D016477:Artifacts; D001863:Bone Screws / Q000009:adverse effects*; D005260:Female; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D008297:Male; D008670:Metals / Q000009:adverse effects*; D019047:Phantoms, Imaging; D011184:Postoperative Period; D059629:Signal-To-Noise Ratio; D013131:Spine / Q000601:surgery; D013997:Time Factors
chemical_list: D008670:Metals